GB2503522A - Process for the preparation of azimsulfuron - Google Patents

Abstract

Processes for the preparation of the herbicidal sulphonamide azimsulfuron (1-(4,6-dimethoxypyrimidin-2-yl)-3-[1-methyl-4-(2-methyl-2H-tetrazol-5-yl)pyrazol-5-ylsulfonyl]urea) or its salts, isomers and other derivatives thereof wherein the process involves treating the pyrazole compound of formula (I) wherein R1 is selected from SH, -SCH2Ph, SR or S-SR1; where R is a straight or a branched chain C1-4alkyl and R1 is a group of formula (II) where * donates the point of attachment; with aqueous acetic acid and chlorine gas or sodium hypochlorite in the presence of hydrochloric acid in chlorinated solvents such as dichloromethane, 1,2-dichloroethane or with aqueous acetic acid and N-chlorosuccinimide or hydrogen peroxide in the presence of hydrochloric acid in aqueous cyclic ether such as tetrahydrofuran, 1,4-dioxane to obtain 1-methyl-4-(2-methyl-2H-tetrazol-5-yl)-1H-pyrazole-5-sulfonyl chloride. The sulfonyl chloride is converted to a sulphonamide and treated with phenyl(4,6-dimethoxypyrimidin-2-yl)carbamate to obtain azimsulfuron or its salts, isomers and other derivatives thereof.

Description

PROCESS OF PREPARATION OF AZIMSULFURON

TECHNICAL FIELD

The present disclosure relates to a process for preparation of a herbicidal sulfonamide, azimsulfuron (l-(4.6-dimethoxypyrirnidin-2-yl)-3-[l -methyl-4-(2-methyl-2I1-tetrazol-5-yl)pyrazol-5-ylsulfonyl]urea) or its salts, isomers, and other derivatives thereof,

BACKGROUND

Sul fonylureas are a family of environmentally compatible herbicides that were discovered by DuPont Crop Protection in 1975 and first commercialized for wheat and barley crops in 1982. They have now been developed and commercialized worldwide in all major agronomic crops and for many specialty uses (e.g., rangelandlpasture, forestry, vegetation management).

Sulfonylureas represent a major advance in global crop protection technology and have revolutionized weed control by introducing a unique mode of action. Specifically, these compounds interfere with a key enzyme required for weed cell growth aeetolaetatc synthase.

Furthermore, sulfonylureas are compatible with the global trend toward post emergence weed control and integrated pest management.

Sulfonylurea herbicides are well known in the art as being highly beneficial for controlling undesirable vegetation in agronornieally desirable crops including corn, cereals such as wheat and barley. They work on a broad range of grasses and broadleaf weeds, but not on crops they are designed to protect. Crops like rice, wheat, barley, soybean, maize, and many others are able to metabolize sulfonylureas safely.

Sulfonyl urea derivatives containing pyrazole ring (pyrazole sulfonylureas) is found to exhibit pronounced herbieidal activity; especially, those in which sulfonyl urea bridge is attached to 51h position of pyrazole ring (pyrazole -5-sulfonyl urea derivatives) are found to be more selective for rice plants from paddy weeds (J pesticide Sd. 15. 531. 1990).

One type of ibis class of sulfonylurea herbicides, Azimsulffiron or I -(4,6-dimethoxypyrimidin-2-yl)-3-[l -methyl-4-(2-methyl-2H-tetrazol-5-yl)pyrazol-5-ylsulfonyl] urea, is well known and has been found to be particularly useful as post emergent herbicides when used against sensitive weeds. It is used post-emergence in rice fields against a variety of airnual weeds. Azimsulfuron affects sensitive weeds through inhibition of the enzyme aeetolaetate synthase (ALS). Inhibition of ALS leads to the cessation of cell division and subsequent growth processes in plants. Azimsulfuron is taken up mainly by leaves and shoots and, to a lesser extent, roots. Once taken up, it is ansloeated via both xylem and phloern.

The Sulfonyl ureas are known in art and can be prepared in a number of different ways such as reaction of either sulfonamide with isocyanate. carbamate & N-carbamoyl chloride of amines or sulfonyl isocyanatc & earbarnate of sulfonamides with amines in presence of base respectively.

US Patent No. 4.746,353. which is incorporated herein by reference in its entirety, discloses a process of preparation of tetrazole substituted sulfonamide herbicides by reacting 3-(2-methyl-2H-tetrazole-5-yl)-l -phenyl-1 H-pyrazole-5-sulfonamide with a phenyl (4.6- dimethoxypyrimidin-2-yl)carbamatc. The 3-(2-methyl-2H-tetrazole-5-yl)-1-phenyl-l1I- pyrazole-5-sulfonarnide was reported to he prepared from 5-arnino-l-phenyl-3-(2-methyl-2H-tctrazol-5-yl)-ll-I-pyrazole via diazotization of it and subsequent treatment of diazonium salt with sulfur dioxide and cupric chloride followed by reaction of intermediate sulfonyl chloride with aqueous ammonia.

US Patent No. 4,650,892 discloses a process of preparation of sulfonamide herbicides using aromatic sulfonyl chlorides and sulfonamides. The preparation of sulfonamide from ammoniurn hydroxide and sulfonyl chloride is reported in literature, e.g. Crossley et.al. .1.

Am. Chem. Soc. 60, 2223 (1938).

US Patent No. 4,169,719 discloses a compound of formula I and its process for preparation.

Fonnulal Where R1 = Compound of formula I was reported to he prepared by reacting substituted 2-amino pyrimidine with appropriately substituted sulfonyl isocyanatc or isothiocynates.

Japanese patent JP7300403A and Chinese research article (Anhul fluagong 37(4), 10- 12, 2011) disclose the process for preparation of azimsulfuron by reacting 1-methvl-4-(2- methyl-2H-tetrazol-5-yl)-l H-pyrazole-5-sulfonamide with phenyl(4,6-dimethoxypyrimidin- 2-yl)earbamatc in presence of 1,8-diazabicyclo[5.4.Oiundec-7-ene and acctonitrile.

Preparation of 1 -methyl-4-(2-methyl-2H-tetrazol-5-yl)-IH-pyrazole-5-sulfonamidc was reported by diazotization of 5-amino-I -methyl-4-(2-rnethyl-2H-tetrazole-5-yl)pyrazole followed by reaction with sulfur dioxide and duprie chloride resulting into sulfonyl chloride.

The sulfonyl chloride converted into sulfonamide by treatment with aqueous ammonia in the presence of tetrahydrofuran.

S The need exists, however, for newer process for preparing these herbicides, like azinisulfuron which destroy or reward weeds without causing significant damage to useful crops.

SUMMARY

The present disclosure reiates to a process for preparation of azimsulfuron or its salts, isomers, and other derivatives thereof, comprising: treating a compound of formula I, or mixtures thereof /

N R1 N(X

formula I wherein, R1 is selected from -SH, -SCH2Ph, -SR or -S-SRi'; where R is a straight or a branched chain C14 alkyl and R1' is a group of formula II and where * denotes the point of attachment / * ft / N

N

Formula II with aqueous acetic acid and chlorine gas or sodium hypoehiorite in presence of hydrochloric acid in chlorinated solvents such as dichloromethane, 1,2-dichioroethane or with aqueous acetic acid and N-chlorosuccinimide or hydrogen peroxide in presence of hydrochloric acid in aqueous cyclic ether such as tetrahydrofuran, 1,4-dioxane to obtain 1-methyl-4-(2-methyl- 21 I-tetrazol-5-yl)-I H-pyrazole-5-sulfonyl chloride; converting the 1 -methyl-4-(2-methyl-21-l-tetrazol-5-yl)-1H-pyrazole-5-sulfonyl chloride to l-methyl-4-(2-methyl-2H-tetrazol-5-yl)-1II-pyrazole-5-sulfonamide in presence of aqueous ammonia and a solvent selected from a chlorinated hydrocarbon, such as diehloromethanc, 1,2-diehloroethane or chloroform; a cyclic ether such as tetrahydrot'uran, or 1,4-dioxane; or a ketone such as acetone, ethyl methyl ketone or methyl isobutyl ketone; and treating the 1 -methyl-4-(2-methyl-2H-tetrazol-5-yl)-I H-pvrazole-5-sulfonamide with phenyl (4,6-dimctboxypvrirnidin-2-yl)carbamate in the presence of an organic base and a polar solvent to obtain azimsulfuron or its salts, isomers, and other derivatives thcreof.

These and other features, aspects, and advantages of the present disclosure wifl become better understood with reference to the following description. This statement is provided to introduce a selection of concepts in a simplified form. This statement is not intended to identi key features or essential features of the subject matter, nor is it intended to be used to limit the scope of the subject matter.

DETAILED DESCRIPTION

The present disclosure will be described morc fully hereinafter. Indeed, the invention can be embodied iii many different forms and should not be construed as limited to the embodiments set forth herein. As used in the specification, and in the appended claims, the singular forms "a", "an", "the", include plural referents unless the context clearly dictates otherwise.

In the present disclosure, the following definitions will apply unless indicated explicitly.

The term "Ci4 alkyl" refers to a monoradieal, branched or unbranched saturated hydrocarbon chain having 1, 2, 3 or 4 carbon atoms. This term is exemplified by groups such as methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl and the like.

The term C1-C4 alkyl thiol' refers to an alkyl thiol group of Ito 4 carbon atoms. The term "C14 alkyl thiol" is exemplified by groups such as methyl thiol, ethyl thiol. n-propyl thiol, iso-propyl thiol, n-butyl thiol, iso-butyl thiol and the like.

The present disclosure provides a process for the preparation of herbicidal sulfonamide, azimsulftron or its salts, isomers, and other derivatives thereof Azimsulftiron is useful as an active ingredient for agroehemieal, especially herbicides.

Azimsulfuron or its salts, isomers, and other derivatives thereof may be used as a foliar, or soil applied herbicides suitable for the control of many annual and perennial broadleaves species in cereals, grains, corn, sugareane and other crops and vine control in pasture and crop land, and can also be used in pre plant or pre emergence applications.

Accordingly, the present disclosure provides a process for preparation of azimsulfiiron or its salts, isomers, and other derivatives thereof, comprising: treating a compound of formula I, or mixtures thereof /

N

Formula I wherein.

S R is selected from -SH, -SCH2Ph, -SR or -S-SR1'; where R is a straight or a branched chain C1A alkyl and R1' is a group of formula II where * denotes the point of attachment Formula II with aqueous acetic acid and chlorine gas or sodium hypochlorite in presence of hydrochloric acid in chlorinated solvents such as dichioromethane, 1,2-dichloroethane or with aqueous acetic acid and N-chlorosuccinimide or hydrogen peroxide in presence of hydrochloric acid in aqueous cyclic ether such as tetrahydrothran. 1,4-dioxane to obtain 1-methyl-4-(2-methyl- 2H-tetrazol-5-yl)-1H-pyrazole-5-sulfonyl chloride; converting the 1 -methyl-4-(2-methyl-2H-tetrazol-5-yt)-1 J-f-pyrazolc-5-sulfonyl chloride to 1-methyl-4-(2-methyl-21J-tctrazol-5-yl)-1H-pyrazole-5-sulfonamidc in presence of aqueous ammonia and a solvent selected from a chlorinated hydrocarbon, such as dichioromethane, l,2-dichloroethane. or chloroform; a cyclic ether such as tetrahydrofuran, or 1,4-dioxanc; or a ketone such as acetone, ethyl methyl ketone or methyl isobutyl ketone; and treating the 1 -mcthyl-4-(2-methyl-2H-tetrazol-5-yl)-lH-pyrazole-5-sulfonamidc with phenyl (4.6-diniethoxypyrimidin-2-yl)carbamatc in the presence of an organic base and a polar solvent to obtain azimsulfliron or its salts, isomers, and other derivatives thereof, In accordance with the present disclosure, the oxidizing agent is suitably selected from any oxidizing agent that can facilitate formation of the sulfonyl chloride. The oxidizing agent is preferably selected from hydrogen peroxide, sodium hypochiorite, N-chiorosuccinimide or chlorine gas.

In an aspect of the present disclosure, the poiar solvent is sclcctcd from N,N-dimethylformamide, N,N-dirnethylacetamide, N-rnethyl-2-pyrrolidone, acetonitrile, acetone, dichiorornethane, 1,2-dichioroethane, methanol, tcahydroftiran, or water; and the organic base is selected from di-isopropyl ethyl amine, di-isopropyl ante, tri-n-biityl amine, triethyl amine, trirncthyl amine or pyridine.

In accordance with the present disclosure, it provides a process for the preparation of azimsulfliron or its sahs. isomers, and other derivatives thereof, comprising: treating a compound of formula I, or mixtures thereof /

N__N N\

Formula I wherein, R1 is selected from -SH, -SCH2Ph. -SR or -S-SRi'; where R is a straight or a branched chain C14 alkyl and K1 is a group of formula II where * denotes the point of attachment if

IL / N /

N

M

Formula II with aqueous acetic acid and chlorine gas or sodium hypochlorite in presence of hydrochloric acid in chlorinated solvents such as dichloromethane. 1,2-dichloroethane or with aqueous acetic acid and N-chlorosuccinimide or hydrogen peroxide in presence of hydrochloric acid in aqueous cyclic ether such as tetrahydrofuran, 1,4-dioxane to obtain l-methyl-4-(2-methyl- 2J1-tetrazol-5-yl)-1 [J-pyrazolc-5-sulfonyl chloride; converting the 1 -methyl-4-(2-rncthyl-2H-tetrazol-5-yl)-J-J-pyrazole-5-sulfonyl chloridc to 1-methyl-4-(2-rnethyl-211-tetrazol-5-yl)-1H-pyrazole-5-sulfonamide in presence of aqueous ammonia and l,2-dichlorocthane; and treating the 1 -methyl-4-(2-methyl-2H-tetrazol-5-yl)-1II-pyrazolc-5-sulfonamide with S phenyl (4.6-dimethoxypyrimidin-2-yl)carbarnate in presence of triethylamine and acetonitrile to obtain azimsulfuron or its salts, isomers, and other derivatives thereof In another embodiment, the compound of formula I is obtained by treating a 5-(5- halo-I-methyl-i H-pyrazole-4-yI)-2-mcthyl-2H-tetrazole or 5-(5-halo-l -methyl-IH-pyrazole- 4-yl)-i-methyl-2H-tetrazole or mixture thereof with a thiol or an alkali hydrosulfide in presence of a solvent selected from N,N-dimethylformarnide. N,N-dimethylaeetamide, N-methyl-2-pyrrolidone, aeetonitrile, acetone, tetraiaydrofuran or water.

In an aspect of the present disclosure, the compound of formula I, wherein R1 is selected from -SH. or -S-SR1; where R1' is a group of formula II where * denotes the point of attachment

I

N * /4

Formula II is obtained by treating a 5-(5-halo-I -methyl-i JI-pyrazole-4-yl)-2-methyl-2H-tetrazole with an alkali metal hydrosulfide in the presence of N,N-dimethylformamide. The alkali hydrosul tide is suitably selected from sodium hydrosulfide or potassium hydrosulfide.

In another aspect of the present disclosure, the compound of formula I, wherein R1 is selected from -SCI-I2Ph or -SR, where R is a straight or a branched chain CiA alkyl, is obtained by treating 5-(5-halo-1-methyl-lH-pyrazole-4-yl)-2-methyl-211-tetrazole with a thiol in the presence of sodium hydride and N,N-dirnethylformamidc.

The thiol used in the present disclosure can be aCM alkyl thiol or benzyl thiol.

In yet another embodiment, the compound 5-(-halo-l-methyl-IH-pyrazole-4-yl)-2- rnethyl-2H-tetrazoie is obtained by halogenating 2-methyl-5-( I -methyl-lH-pyrazol-4-yl)-2H-tetrazote with a halogenating agent, selected li-orn N-chlorosuccinimide, N-hromosueeinimide or N-iodosuccinimide in the presence of a solvent selected from N,N-dimcthylformamide, N,N-dirnethylacetamide, N-methyl-2-pyrrolidone. aeetonitri Ic, acetone. dichioromethane, 1,2-diehlorocthane, methanol, tetrahydroftiran, ethyl acetate, or butyl acetate.

The 5-(5-halo-1-mcthyl-1JI-pyrazote-4-yl)-2-methyl-2H-tetrazole described in the present disclosure is obtained by treating l-methyl-lH-pyrazole with phosphoryl chloride in the presence of N,N-dimethylformamide, to obtain 1-methyl-1H-pyrazole-4-earbaldehyde; treating the 1-methyl-1H-pyrazole-4-earhaldehyde with hydroxylarnine hydrochloride in the presence of ethanol, to obtain l-inethyl-1H-pyrazole-4-earhaldehyde oxime; treating the l-rnethyl-1H-pyrazole-4-earbaldehyde oxirne with sodium azide in the presence of ammonium chloride and N,N-dimethylformamide, to form S-(l-methyl-1H-pyrazole-4-yl)-2H-tetrazole; reacting the 5-(l-methyl-1H-pyrazol-4-yI)-2f/-tcfrazole with methyl iodide or dimethyl sulphate, in the presence of potassium hydroxide or potassium carbonate to obtain 2-methyl-5-(l-methyl-1H-pyrazol-4-yl)-2//-tctrazole or l-methyl-5-(I -methyl-1H-pyrazol-4-yl)-1 JI-tetrazole or mixtures thereof; and halogenating 2-rnethyl-5-( 1-methyl-I H-pyrazol-4-yl)-211-tetrazole th N- halosuccinimide, in the presence aeetonitrile, to obtain a 5-(5-halo-l-methyl-1H-pyrazol-4-yl)-2-rnethyl-2H-tetrazole.

The regio-isomcrs, 2-methyl-5-(I -methyl-i TI-pyrazol-4-yl)-2H-tetrazole or 1 -methyl- -(1-methyl-lH-pyrazol-4-yl)-I II-tetrazolc or mixtures thereof obtained in the present disclosure were separated. The desired regio-isomer, 2-methyl-5-(i-methyl-1H-pyrazol-4-yl)- 211-tetrazole. was isolated by column chromatography. The desired regio-isorner, 2-methyl-5- (I-methyl-I H-pyrazol-4-yl)-21J-tcfrazole is further used for the preparation of azimsulftiron, or its salts, or other derivatives thereof by the process of the present disclosure.

The 5-(5-halo-1-methvl-1H-pyrazole-4-yl)-2-methyl-2H-tetrazole or its regio-isomer 5-(5-halo-l -methyl-I ll-pyrazole-4-yl)-I -methyl-lI-I-tetrazole, or mixtures thereof described in the present disclosure can also be obtained by methylating a 5-(5-halo-1-methyl-1H-pyrazole-4-yl)-2/J-tetrazole with a methylating agent, such as dimethyl sulfate, methyl iodide or methyl bromide, and a base selected from an alkali metal hydroxide base, such as sodium hydroxide, potassium hydroxide or lithium hydroxide; or an alkali metal carbonate base, such as sodium carbonate, sodium bicarbonate, potassium carbonate or cesium carbonate; or an organic base such as triethyl amine, di-isopropyl amine, di-isopropyl ethyl amine, pyridine, pyrrolidine or N,N-dimethyl aniline, in the presence of a polar solvent such as N.N-dimethylformaniide, N,N-diniethylaeetamide, N-methyl-2-pyrrolidone. acetonitrile, acetone, dichloromethane, 1,2-dichloroethane, methanol, tetrahydrofuran or water.

Methylation of 5-(5-halo-I -methyl-1H-pyrazolc-4-yl)-2H-tctrazole as described in the present disclosure gives 5-(5-halo-l-rnethyl-IH-pvrazole-4-yl)-2-methyl-21l-tetrazole, or its regio-isomer 5-(5-halo-i -methyl-i H-pyrazole-4-yl)-l-methyl-1H-tetrazole, or mixtures thereof The desired regio-isomer, 5-(5-halo-l -methyl-1H-pyrazol-4-yl)-2-methyl-2H-tetrazole), was isolated by column chromatography at this stage or at the next thiol preparation step. After this step only the desired regiomer i.e. 5-(5-halo-1-methyl-lT-I-pyrazole-4-yl)-2-niethyl-2H-tetrazole is used for the preparation of azinisulfuron. or its salts, or other derivatives thereof.

The 5-(5 -halo-i -methyl-1H-pyrazole-4-yl)-2H-tetrazole compound described in the present disclosure can be obtained by any known process in the art. Particularly, in an aspect of the present invention, this tetrazole compound used for further preparation of azimsulfuron by the process of the present disclosure, is obtained by treating malononitrile with triethyl orthoformate in the presence of acetic anhydride to obtain 2-(ethoxymethylene)malononitrile; treating the 2-(ethoxymethylcnc)malononitrile with an N-methyl hydrazine sulfate or N-methyl hydrazine, and a base selected from an alkali metal hydroxide base such as sodium hydroxide, potassium hydroxide or]ithium hydroxide; or an alkali metal carbonate base such as sodium carbonate, sodium bicarbonate, potassium carbonate or cesium carbonate; or an organic base such as triethyl amine, di-isopropyl amine, di-isopropyl ethyl amine, pyridine, pyrrolidine or N,N-dinicthyl aniline, in the presence of an alcohol such as methanol, ethanol or propanol to obtain 5-amino-I -methyl-i Ji-pyrazole-4-carbonitrile; halogenating the 5-amino-1-methyl-I H-pyrazole-4-carhonitrile with sodium nitrite and a cuprous halide such as cuprous chloride. cuprous bromide or cuprous iodide, with a mineral acid such as hydrochloric acid, hydrobromic acid or sulfuric acid, to obtain a 5-halo- 1-methyl-1 H-pyrazole-4-carbonitrile; and treating the 5-halo-l-methyl-lIJ-pyrazole-4-carbonilriie with sodium azide in the presence of either an ammonium halide such as ammonium chloride, ammonium bromide or ammonium iodide, and a polar solvent such as N,N-dimcthylfommmide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, 1.2-dichloroethane, tetrahydrofturan or water; or a tri-n-butyl tin halide such as tri-n-butyl tin chloride, tri-n-butyl tin bromide or tri-n-hutyl tin iodide, and a non polar solvent such as totuene, xyiene or benzene. to obtain a 5-(5-halo-1-methyl-IH-pyrazole-4-yl)-2H-tetrazole).

Another embodiment of the present disclosure provides a process for preparing 5-(5-halo-i -methyl-i JI-pyrazole-4-yl)-2-methyl-21/-tctrazolc by a process comprising: treating 1-med yl-1H-pyrazole with iodine and hydrogen peroxide in aqueous medium to obtain 4-iodo-1-methyl-I H-pyrazole; treating the 4-iodo-1-methyl-lII-pyrazole with potassium ferrocyanide and palladium (11) acetate in the presence ol sodium carbonate, and N,N-dimethylacetamide. to obtain 1-methyl-I TT-pyrazol e-4-carbonitrile; treating the I -methyl-I T-l-pyrazole-4-earbonitrile with sodium azide and either with tri-n-butyl tin chloride in the presence of toluene, or ammonium chloride in the presence of N,N-dimethylformamide to obtain 5-( 1-methyl-I JJ-pyrazol-4-yl)-2H-tetrazole; reacting the 5-(1-methyl-1H-pyTazole-4-yl)-2H-tetrazole with methyl iodide and dimethyl sulphate, in the presence of potassium hydroxide and potassium carbonate to obtain 2-methyl-5-(l-methyl-1H-pyrazoi-4-yl)-2H-tetrazole, or I -methyl-5-( 1 -rnethyl-1H-pyrazoi- 4-ye-L1J-tetrazoie and mixtures thereof; and halogenating the 2-methyl-5-( I-methyl-i Lt-pyrazol-4-yl)-2H-tetrazole with N- haiosuccinimide, in the presence acctonitrilc, to obtain a 5-(5-halo-l-rnethyl-IfJ-pyrazol-4-yl)-2-methyl-2H-tetrazole.

The regio-isorners, 2-methyl-5-(l -methyl-I ff-pyrazoi-4-yl)-2H-tetrazole or 1-methyl- 5-( 1-methyl-I H-pyrazol-4-yl)-1II-tetrazole or mixtures thereof obtained in the present disclosure were separated. These regio-isomers can form azimsulftron or its isomers ftrther the process of the present disclosure. In a preferred embodiment, the regio-isomer, 2-methyl- 5-(l -methyl-I H-pyrazol-4-yl)-2H-tetrazole, was isolated by column chromatography and was further used for the preparation of azimsulftuon, or its. salts, or other derivatives thereof In one of aspect of the present disclosure, it provides a process for preparation of azimsulfuron or its salts, isomers, and other derivatives thereot comprising: treating 5-(5-chloro-l -methyl-1H-pyrazole-4-yl)-2-methyl-2H-tetrazole with hcnzyl thiol in thc presence of N,N-dimethylformarnide and sodium hydride to obtain the compound 5-(5-(benzyithio)-1-methyl-1H-pyrazol-4-yl)-2-methyl-2J1-tetrazole of formula I, wherein R1 is -SCII2Ph, /

N -N

Formula I treating the compound 5-(5-(benzylthio)-l -methyl-] H-pyrazol-4-yl)-2-methyl-2H-tetrazole of formula I with aqueous acetic acid and chlorine gas or sodium hypochiorite in presence of hydrochloric acid in chlorinated solvents such as dichloromethane, 1,2-dichioroethane or with aqueous acetic acid and N-chlorosuccinimide or hydrogen peroxide in S presence of hydrochloric acid in aqueous cyclic ether such as tetrahydrofuran, I,4-dioxane to obtain 1 -methyl-4-(2-methyl-2H-tetrazol-5-yl)-1H-pyrazole-5-sulfonyl chloride; converting the I -niethyl-4-(2-rnethyl-2H-tetrazol-5-yl)-1II-pyrazole-5-sulfonvl chloride to 1 -methyl-4-(2-methyl-2H-tetrazol-5-yl)-IH-pyrazole-5-sulfonamide in the presence of aqueous ammonia and 1,2-dichloroethanc; and treating the 1 -methyl-4-(2-rnethyl-2H-tetrazol-5-yl)-IH-pyrazole-5-sulfonamide with phenyl (4,6-dimethoxypyTimidin--2-yl) carbamate in the presence of triethylamine and acetonitrile to obtain azimsulftiron or its salts, isomers, and other derivatives thereof.

In another aspect of the present disclosure, it provides a process for preparation of azimsulfuron or its salts, isomers, and other derivatives thereof, comprising: treating 5-(5-chloro-l-mcthyl-l H-pyrazole-4-yl)-2-methyl-211-tetrazole with sodium hydrosulfide in the presence of N,N-dimethylformamide to obtain the compounds (1-methyl- 4-(2-methyl-2H-tetrazol-5-yl)-IH-pyrazole-5-thiol), or its disulfide (1,2-bis-(l-methyl-4-(2-mnethyl-2H-tetrazol-5-yI)-1H-pyrazol-5-yl) disulfanc), or mixture thereof; treating the (1 -methyl-4-(2-mnethyl-2H-tetrazol-5-yl)-IH-pyrazole-5-thiol), or its disulfide (l,2-bis-(l-methyl-4-(2-rnethyl-2H-tetrazol-5-yl)-1H-pyrazol-5-yl) disulfane), or mixture thereof, with aqueous acetic acid and chlorine gas or sodium hypochlorite in presence of hydrochloric acid in chlorinated solvents such as dichloromethane, 1,2-dichloroethane or with aqueous acetic acid and N-chlorosuccinimide or hydrogen peroxide th presence of hydrochloric acid in aqueous cyclic ether such as tetrahydroffiran, I,4-dioxanc to obtain 1 -methyl-4-(2-methyl-2H-tetrazol-5-yl)-1H-pyrazole-5-sulfonyl chloride; converting the I -mcthyl-4-(2-methyl-2/I-tctrazol-5-yl)-1H-pyrazole-5-sulfonyl chloride to 1-mcthyl-4-(2-mcthyl-2H-tctrazol-5-yl)-IH-pyrazole-5-sulfonamide in the presence of aqueous ammonia and I,2-dichloroethane; and treating the I -rncthyl-4-(2-rncthyl-2H-tetrazol-5-yl)-l H-pyrazole-5-sul fonamide with phenyl (4,6-dimethoxypyrimidin-2-yl)carbamate in the presence of triethylamine and acetonitrile to obtain azimsulfuron or its salts, isomers, and other derivatives thereof.

In accordance with the present disclosure, the (l-mcthyl-4-(2-methyl-2H-tetrazol-5-yD-I H-pyrazole-5-thiol) is of the fomiula: /

N _ N

SH

and its disulfide (l,2-bis-(l-methyl-4-(2-methyl-2H-tetrazol-5-yl)-IH-pyrazol-5-yl) disulfane), is of the formula:

NN / \\

T

N \\ /

N ---N

N

Another aspect of the present disclosure provides a process for preparation of azimsulfuron or its salts, isomers, and other derivatives thereof, comprising: chlorinating 2-methyl-5-( 1 -methyl-1H-pyrazol-4-yl)-2H-tetrazo Ic with N- chiorosuccinimide, in the presence acetonitrile, to obtain 5-(5-chloro-1 -rnethyl-IH-pyrazol-4-y-2-methvl-2[f-tctrazo1e; treating the 5-(5-chloro-1 -methyl-1H-pyrazole-4-yl)-2-mcthyl-2H-tetrazole with sodium hydrosulfide in the presence of N,N-dirnethylforrnamide to obtain the compounds (1- methyl-4-(2-rnethyl-2H-tetrazol-5-yl)-1II-pyrazole-5-thiol), or its disulfide (I,2-bis-(1-methyl-4-(2-rnethy[-21J-tetrazol-5-yl)-IH-pyrazol-5-yl) disulfane), or mixture thereof; treating the (I -methyI-4-(-rnethy1-2Jf-tetrazo1-5-y1)-1H-pyrazo1e-5-thiol), or its disulflde (I,2-bis-(l-Inethyl-4-(2-methyl-2H-tetrazol-5-yl)-lIi-pvrazol-5-yl) disulfane), or mixture thereof, with aqueous aceue acid and chlorine gas or sodium hypochlorite in presence of hydrochloric acid in chlorinated solvents such as dichioromethane. 1.2-diehioroethane or with aqueous acetic acid and N-chlorosuceinimide or hydrogen peroxide in presence of hydrochloric acid in aqueous cyclic ether such as tetrahydrofuran, 1.4-dioxane to obtain 1 -methyl-4-(2-methyl-2H-tetrazol-5-yl)-I J1-pyrazole-5-sulfonyl chloride; converting the 1 -meihyl-4-(2-methyl-2H-tetrazol-5-yl)-I H-pyrazoie-5-sulfonyl chloride to 1-methyl-4-(2-rnethyl-2H-tetrazol-5-yl)-1H-pyrazole-5-sulfonamide in the presence of aqueous ammonia and 1,2-dichioroethane; and treating the 1 -mcthyl-4-(2-methyl-2H-tetrazol-3-yl)-1 H-pyrazole-5-sulfonamide with phenyl (4,6-dimethoxypyrirnidin-2-yl)carbamate in the presence of triethylamine and acetonitrile to obtain azimsulfuron or its salts, isomers, and other derivatives thereof.

In another embodiment, it provides a process for preparation of azimsulfuron or its salts, isomers, and oilier derivatives thereoL comprising: chlorinating 2-niethyl-5-( 1-methyl-i H-pyrazol-4-yl)-2H-tetrazole with N- chiorosuccinimide, in the presence acetonitriie, to obtain 5-(5-chloro-1-methyl-IH-pyrazol-4-yI)-2-methyl-2H-tetrazole.; treating the 5-(5-chioro-1-methyl-1H-pyrazole-4-yl)-2-methyl-2H-tetrazole with bcnzyl thiol in the presence of a,N-dimethylfoimamide and sodium hydride to obtain compound 5-(5-(benzylthio)-1-methyl-i H-pyrazol-4-yl)-2-methy!-2H-tetrazole of formula 1, wherein R1 is -SCH2Ph, /

N N Nh

Formula I treating the compound 5-(5-(benzylthio)-1 -methyl-1H-pyrazol-4-yl)-2-rnethyl-2H-tetrazole with aqueous acetic acid mid chlorine gas or sodium hypochiorite in presence of hydrochloric acid in chlorinated solvents such as dichloroniethane, 1,2-dichlorocthane or with aqueous acetic acid and N-chlorosuccinimide or hydrogen peroxide in presence of hydrochloric acid in aqueous cyclic ether such as tetrahydrofliran, I,4-dioxane, to obtain I -methyl-4-(2-methyl-2ff-tetrazoi-5-yl)-1 H-pyrazole-5-sulfonyl chloride; converting the I -methyl-4-(2-rnethyl-2H-ietrazol-5-yl)-1H-pyrazole-5-sulfonyl chloride to l-methyl-4-(2-methyl-2H-tetrazol-5-yl)-lH-pyrazole-5-sulfonamide in the presence of aqueous ammonia and I,2-dichloroethane; and treating the 1 -niethyl-4-(2-rnethyl-2H-tetrazoi-5-yl)-1H-pyrazoie-5-sulfonamide with pheny! (4,6-dimethoxypyrimidin-2-yl)carbamate in the presence of triethylamine and acetonitrile to obtain azimsulfuron or its salts, isomers, and other derivatives thereof.

In yet another aspect of the present disclosure, it provides a process for preparation of azimsulftron or its salts, isomers, and other derivatives thereof, comprising: methylating 5-(5-chloro-1-methyl-1H-pyrazole-4-yl)-211-tctrazolc with a methylating agent, such as dimethyl sulfate, methyl iodide or methyl bromide, and potassium carbonate, in the presence of acetone to obtain 5-(5-chloro-1-methyl-iT[-pyrazole-4-yi)-2-methyl-211-tetrazole or its regio-isomers 5-(5-chloro-1-methyl-1H-pyrazole-4-yl)-1 -rnethyl-2H-tetrazole, or mixtures thereof; treating the 5-(5-chloro-1-methyl-i ff-pyrazoIe-4-yl)-2-methy-2II-tetrazole or its regio-isomers 5-(5-chloro-1-methyl-1H-pyrazole-4-yl)-1-methvl-2H-tetrazole, or mixtures thereof with sodium hydrosulfide in the presence of N,N-dimethylformamide to obtain the compounds (I -mcthyl-4-(2-methyl-2H-tetrazol-5-yi)-1H-pyrazole-5-thiol). or its disulfide (1,2-bis-(1-methyl-4-(2-methyl-2H-tetrazol-5-yl)-1 /J-pyrazo-5-yl)disulfane). or mixture thereofi treating the (i-methyl-4-(2-methy-2II-tetrazoi-5-yl)-lH-pyrazoie-5-thiol), or its disuifide (1 2-bis-(i-mcthyl-4-(2-methyl-2H-tetrazo!-5-yl)-l!J-pyrazol-5-yl)disulfane), or mixture thereof with aqueous acetic acid and chlorine gas or sodium hypocliori1e in presence of hydrochloric acid in chlorinated solvents such as dichloromethanc, 1,2-diehloroethane or with aqueous acetic acid and N-chlorosuccininiide OT hydrogen peroxide in presence of hydrochloric acid in aqueous cyclic ether such as tetrahydrofuran, 1,4-dioxane, to obtain I -mcthyl-4-(2-niethyi-211-tetrazol-5-yl)-1H-pyrazole-5-sulfonyl chloride; converting the I -methyl-4-(2-methyl-2H-tetrazol-5-yl)-lH-pyrazole-5-sulfonyl chloride to 1 -methyl-4-(2-n-iethyl-2H-tetrazol-5-yl)-1H-pyrazole-5-sulfonamide in the presence of aqueous ammonia and I,2-dichloroetEane; and treating the 1 -methyi-4-(2-methyl-2H-tetrazol-5-yl)-I //-pyrazole-5-sulfonamide with phenyl (4,6-dimethoxypyrirnidin-2-yi)carbamate in the presence of triethylarnine and acetonitrile to obtain azimsuifliron or its salts, isomers, and other derivatives thereof.

In another embodiment, it provides a process for preparation of azinisulffiron or its salts, isomers, and other derivatives thereof; comprising: niethylating 5-(5-chloro-i-methyl-1H-pyrazole-4-yi)-2H-tetrazoie with a methylating agent, such as dimethyl sulfate, methyl iodide or methyl bromide, and potassium carbonate, in the presence of acetone to obtain 5-(5-chloro-i-methyl-1H-pyrazole-4-yi)-2-methyi-2H-tetrazole or its regio-isomers 5-(5-chioro-l-methyl-1H-pyrazole-4-yI)-i -methy-2H-teLrazo1e, or mixtures thereof; treating the 5-(5-chloro-1-methyl-lH-pyrazole-4-yl)-2-methyi-2H-tetrazole or its regio-isomers 5-(5-ehioro-1-methyl-lH-pyrazoIe-4-y-i -methyl-211-tetrazole, or mixtures thereof with benzyi thiol in the presence of a N,N-dimethylformamide and sodium hydride to obtain compound 5-(5-(benzylthio)-1 -methyl-1II-pvrazol-4-yl)-2-methyl-211-tetrazole of fonnula I, wherein R1 is -SCH2Pb, / Fomnila I treating the compound 5-(5-(benzylthio)-1 -methyl-I JJ-pyrazol4-yl)-2-methyl-2H-tetrazole with aqueous acctie acid and chlorine gas or sodium hypochlorite in presence of hydrochloric acid in chlorinated solvents such as dichloromethane. 1,2-dichloroethanc or with aqueous acetic acid and N-chlorosuccinimidc or hydrogen peroxide in presence of hydrochloric acid in aqueous cyclic ether such as tetrahydrofuran, 1,4-dioxane, to obtain 1-methyl-4-(2-methyl-2H-tetrazol-5-yl)-1 fJ-pyrazole-5-sulfonyl chloride; converting the I -methyl-4-(2-rnethyl-2H-tetrazol-5-yl)-1H-pyrazole-5-sulfonyl chloride to 1 -methy l-4-(2-methy1-2H-teazol-5-y1)-1JJ-pyrazolc-5-sulfonamide in the presence of aqueous ammonia and I,2-dichloroethane; and treating the 1 -methyl-4-(2-methyl-2J1-tetrazol-5-yl)-1 II-pyrazole-5-sulfonamide with phenyl (4.6-dimethoxypyrimidin-2-yl)carbamate in the presence of triethylamine and acetonitrile to obtain azimsulftron or its salts, isomers, and other derivatives thereof In another aspect of the present disclosure, it provides a process for preparation of azimsulfuron or its salts, isomers, and other derivatives thereof; comprising treating 1-methyl-I H-pyrazolc with phosphoryl chloride in the presence of N,N-dimethylformamide, to obtain 1-methyl-i H-pyrazole-4-carhaldehyde; treating the I -methyl-1H-pyrazole-4-carbaldehyde with hydroxylamine hydrochloride in the presence of ethanol, to obtain 1-methyl-i fl-pyrazole-4-carba.ldehyde oxime; treating the 1-methyl-IH-pyrazolc-4-carbaldehyde oxime with sodium azide in the presence of ammonium chloride and N,N-dimethylformamide, to form 5-(1-methyl-1iI-pyrazole-4-yl)-2H-tetrazole; reacting the 5-( 1-methyl-lH-pyTazol-4-yl)-2H-tetrazole with methyl iodide and dimcthyl sulphate, in the presence of potassium hydroxide and potassium carbonate to obtain 2-methyl-5-(1-methyl-1H-pyrazol-4-yI)-2H-tetrazole; chlorinating the 2-methyl-5-(l -methyl-IH-pyrazol-4-yl)-2H-tetrazole with N-chloro succinimide, in the presence acctonitrilc, to obtain 5-(5-chloro-l-rnethyl-IH-pyrazol-4-yl)-2-methyl-2H-tetrazole; treating the 5-(5 -chioro-1-methyl-i H-pyrazole-4-yl)-2-rnethyl-2H-tetrazole with S benzyl thiol in the presence of N,N-dimethylformamide and sodium hydride to obtain compound 5-(5-(benzylthio)-1 -methyl-1H-pyrazol-4-yl)-2-methyl-2H-tetrazole of formula I, wherein R1 is -SCH2Ph; /

N_N

Formula I treating the compound 5-(-(bcnzy1thio)-1-methyl-1 H-pyrazol-4-yI)-2-methyl-2H-tetrazole aqueous acetic acid and chlorine gas or sodium hypochlorite in presence of hydrochloric acid in chlorhiated solvents such as dichioromethane, l,2-dichloroethane or with aqueous acetic acid and N-chlorosuccinirnide or hydrogen peroxide in presence of hydrochloric acid in aqueous cyclic ether such as tctrahydrofuran, 1,4-dioxane, to obtain 1-methyl-4-(2-methyl-2H-tetrazol-5-yl)-1 I!-pyrazole-5-suifonyl chloride; converting the 1-methyl-4-(2-methyl-2Ji-tctrazoI-5-y-lJJ-pyrazole-5-sulfonyl chloride to 1 -rnethyl-4-(2-n1ethyl-2H-tetrazol-5-yl)-1H-pyrazole-3-sulfonamide in the presence of aqueous ammonia and 1,2-dichloroethane; and treating the 1 -methyl-4-(2-mcthyl-211-tctrazol-5 -yl)-I H-pyrazole-5-sulfonaniide with phenyl (4,6-dimethoxypyrimidin-2-yl)carbarnate in the presence of triethylamine and acetonitriie to obtain azimsulftiron or its salts, isomers, and other derivatives thereof In yet another aspect of the present disclosure, it provides a process for preparation of azimsulfuron or its salts, isomers, and other derivatives thereoL comprising trcating 1 -methyl-1II-pyrazolc with phosphoryl chloride in the presence of N,N-dimethylformamide, to obtain 1 -methyl-1H-pyrazole-4-carbaldehyde; treating the I -methyl-1 H-pyrazole-4-carbaldehyde with hydroxylamine hydrochloride in the presence of ethanol, to obtain 1-methyl-I H-pyrazolc-4-carbaldchydc oxinie; treating the 1-methyl-IH-pyrazole-4-carbaldehyde oxirne with sodium azide h the presence of ammonium chloride and N,N-dimcthylformamide, to form 5-(1-methyl-1H-pyrazole-4-yl)-2H-tetrazole; reacting the 5-a-methyl-i H-pyrazol-4-yl)-2H-tetrazole with methyl iodide and dirnethyl sulphate, in the presence of potassium hydroxide and potassium carbonate to obtain 2-methyl-S -(1 -methyl-I H-pyrazol-4-yl)-211-tetrazole; chlorinating the 2-rnethyi-5 -(i-methyl-lH-pyrazol-4-yl)-2H-tetrazole with N- chlorosuccinirnide, in the presence acetonitrile, to obtain 5-(5-chloro-I-rnethyl-iH-pyrazol-4-yl)-2-methyl-2H-tetrazole; treating 5-(S-chloro-i -rnethyl-IH-pyrazoie-4-yi)-2-methyl-2H-tetrazoie with sodium hydrosulfide in the presence of N,N-dimethylformamide to obtain the compounds (I-methyl- 4-(2-methyl-2H-tetrazol-5-yl)-iH-pyrazoie-5-thiol), or its disulfide (i,2-bis-(1-methyl-4-(2-methyl-2H-tetrazol-S-yl)-IH-pyrazol-5-yl) disulfane), or mixture thcrcof: treating the (i -methyl-4-(2-methyi-2H-tctrazoi-S-yl)-1 H-pyrazolc-5-thiol), or its disulfide (I,2-bis-(1-rnethyl-4-(2-methyl-2H-tetrazol-5-yi)-1H-pyrazol-5-yl) disulfane), or mixture thereof, with aqueous acetic acid and chlorine gas or sodium hypochiorite in presence of hydrochloric acid in chlorinated soivcnts such as dichloromethane, I,2-dich]oroethane or with aqueous acetic acid and N-cltlorosuccinimide or hydrogen peroxide in presence of hydrochloric acid in aqueous cyclic ether such as tetrahydroluran, i,4-dioxane, to obtain 1 -methyl-4-(2-methyl-211-tetrazol-S-yl)-IH-pyrazole-S-sulfonyl chloride; converting the 1 -mdli yl-4-(2-rnethyi-2H-tetrazoi-5-yI)-1H-pyrazoie-5-sulfonyl chloride to I -methyi-4-(2-methyi-2H-tetra2ol-5-yl)-iH-pyrazole-5-sulfonamide in the presence of aqueous ammonia and 1,2-dichloroethane; and treating the 1-rnethyl-4-(2-methyl-2H-tetrazol-5-yl)-lH-pyrazoie-S-suifonamide with phenyl (4.6-dimethoxypyrimidin-2-yl)earbarnate in the presence of triethylamine and acetonitrile to obtain azimsulfuron or its salts, isomers, and other derivatives thereof in another aspect of the present disclosure, it provides a process for preparation of azimsulftiron or its salts, isomers, and other derivatives thereof; comprising: treating malononitrile with triethyl orthoformate in the presence of acetic anhydride to obtain 2-(ethoxymethyiene) malononitrile; treating the 2-(ethoxyrnethylene) malononitrile with N-methyl hydrazine sulfate or N- methyl hydrazine and triethyl amine, in the presence of methanol to obtain 5-amino-I-methyl-I [J-pyrazole-4-carbonitrile; chlorinating the 5-amino-l-methyl-lJT-pyrazolc-4-earbonitrilc with sodium nitrite and euprous chloride, with hydrochloric acid to obtain 5-ehioro-i-methyl-I H-pyrazole-4-carhonitrile; treating the 5-chloro-l -methyl-lII-pyrazole-4-carbonitrile with sodium azide in the presence of either ammonium chloride, and N,N-dimethyiformamide, or tri-n-butyl tin chloride and toluene, to obtain 5-(5-chloro-1 -methyl-I Jf-pyrazole-4-yI)-2H-tetrazole); methylating the 5-(5-chloro-l-methyl-IH-pyrazole-4-yl)-2H-tetrazoie with a methylating agent, such as dimethyl sulfate, methyl iodide or methyl bromide; and potassium carbonate, in the presence of acetone to obtain 5-(5-chloro-1-methyl-1H-pyrazole-4-yl)-2- methyl-21-J-tctrazole or its regio-isoniers 5-(5-chloro-1-methyl-tIi-pyrazole-4-yl)-1 -methyl- 211-tctrazolc, or mixtures thereof; treating the 5-(5-chloro-1 -methyl-i H-pyrazole-4-yl)-2-methyl-2L1-tetrazole or its regio-isomers 5-(5-chloro-i-methyl-1H-pyrazolc-4-yl)-i-rnethyi-2H-tetrazole, or mixtures thereof with bcnzyl thiol in the presence of N,N-dimethylfomumide and sodium hydride to obtain compound 5-(5-(henzylthio)-l -methyl-1H-pyrazol-4-yl)-2-methy!-21/-tetrazole of formula I, wherein R1 is -SCII2Ph; / NtI Formula I treating the compound 5-(5-(henzy]thio)-i-rnethyl-1H-pyrazol-4-vl)-2-methyl-211-tetrazole with aqueous acctic acid and chlorine gas or sodium hypochiorite in presence of hydrochloric acid in chlorinated solvents such as dichioromethane, 1,2-dichlorocthane or with aqueous acetic acid and N-chlorosuccinimide or hydrogen peroxide in presence of hydrochloric acid in aqueous cyclic ether such as tetrahydrofuran, I,4-dioxane, to obtain 1-methyl-4-(2-methyl-2H-tctrazol-5-yI)-I J/-pyrazole-5-sulfonyl chloride; converting the I -methyl-4-(2-methyl-2H-tetrazol-5-yl)-1H-pyrazole-5-sulfonyl chloride to 1 -methyl-4-(2-methyl-2H-tetrazol-5-yl)-1H-pyrazole-5-sulfonamide in the presence of aqueous ammonia and 1,2-dichioroethane; and treating the I -methyl-4-(2-rnethyl-2H-tetrazol-5-yl)-1 H-pyrazole-5-sulfonamide with phenyl (4,6-dimethoxypyrimidin-2-yl)earbamate in the presence of triethylamine and acetoniUile to obtain azimsulfuron or its salts, isomers, and other derivatives thereof Another embodiment provides a process for preparation of azimsulfuron or its salts, isomers, and other derivatives thereof comprising: is treating malononitrile with triethy] orthoformate in tile presence of acetic anhydride to obtain 2-(ethoxymethylene) malononitrile; treating the 2-(ethoxymethylene) malononitrile with N-methyl hydrazine suffate and triethyl amine, in the presence of methanol to obtain 5-amino-1-methyl-1H-pyrazole-4-carbonitrile; chlorinating the 5-amino-1-methyl-lH-pyrazole-4-carbonitrile with sodium nitrite and cuprous chloride, with hydrochloric acid to obtain 5-chioro-1-methyl-lH-pyrazole-4-carhonitrile; treating the 5-chloro-l-methyl-1H-pyrazole-4-carhonitrilc with sodium a.zide in the presence of either anirnonium chloride, and N,N-dimethylformamide, or tri-n-butyl tin chloride and toluene, to obtain 5-(5-chloro--methyl-TH-pvrazole-4-yl)-2H-tetrazole); methylating the 5-(5-chloro-l -mcthyl-1H-pyrazole-4-yi)-2H-tetrazole with dirnethyl sulfate and potassium carbonate, in the presence of acetone to obtain 5-( -chloro-1 -methyl- lH-pyrazolc-4-yl)-2-methyl-2H-tetrazole or its regio-isomers 5-(5-chloro-1 -methyl-1H-pyrazole-4-yl)-1 -methyl-2H-tetrazolc, or mixtures thereof; treating the 5-(5-ehloro-1-methyl-1H-pyrazole-4-yl)-2-methyl-2J1-tctrazolc or its regio-isomers 5-(5-ehloro-1 -methyl-lH-pyrazole-4-yl)-1-methyl-2H-tetrazole, or mixtures thereof with sodium hydrosulfide in the presence of a N,N-diniethylformanñde to obtain the compounds (1 -methyl-4-(2-methyl-2H-tetrazol-5-yl)-1H-pyrazole-5-thiol), or its disulfide (l,2-bis-(1-methyl-4-(2-methyl-211-tetrazol-5-yl)-1H-pyrazol-5-yl) disulfane), or mixture thereof; treating the (1 -methyL4-(2-methyl-2H-tetrazol-5-yl)-lH-pyrazole-5-thiol), or its disulfide (1,2-his-C -methyl-4-(2-rnethyl-2JI-tetrazol-5-yl)-1H-pyrazol-5-yl)disulfane), or mixture thereof with aqueous acetic acid and chlorine gas or sodium hypochlorite in presence of hydrochloric acid in chlorinated solvents such as dichloromcthanc, 1,2-dichlorocthanc or with aqueous acetic acid and N-chlorosuceinimide or hydrogen peroxide hI presence of hydrochloric acid in aqueous cyclic ether such as tetrahydrofuran I,4-dioxane, to obtain I -methyl-4-(2-methyl-2H-tetrazol-5-yI)-1 ff-pyrazole-5-sulfonyl chloride; converting the l-methyl-4-(2-methyl-211-tetrazol-5-yl)-1 H-pyrazole-5-sult'onyl chloride to 1-methyl-4-(2-methyl-2H-tetrazol-5-yl)-1H-pyrazole-5-sulfonamidc in the presence of aqueous ammonia and l,2-dichloroethane; and treating the 1 -methyl-4-(2-methyl-2H-tetrazol-5-yl)-I iI-pyrazolc-5-sulfonarnide with phenyl (4,6-dimethoxypyrimidin-2-yl)earbamate in the presence of triethylaniine and acetonitrile to obtain azimsulfiutn or its salts, isomers, and other derivatives thereof Still another embodiment of present disclosure provides a process for preparation of azimsulThron or its sahs, isomers, and other derivatives thereof, comprising: treating l-methyl-1H-pyrazole with iodine and hydrogen peroxide in aqueous medium to obtain 4-iodo-1-methyl-] J-1-pyrazole; treating the 4-iodo-i-niethyl-1H-pyrazole with potassium ferrocyanide and palladium (11) acetate in the presence of sodium carbonate, and N,N-dimethylacctamidc, to obtain 1-methyl-liI-pyrazole-4-carbonitrile; treating the 1-methyl-1H-pyrazole-4-carbonitrile with sodium azide and either with tri-n-butyl tin chloride in the presence of toluene, or ammonium chloride in the presence of N,N-dimethylformamide to obtain 3-(l -methyl-I JJ-pyrazol-4-y])-2H-tetrazole; reacting the 5-(1 -methyl-1 H-pyrazole-4-yl)-2H-tetrazole with methyl iodide and dimethyl sulphate, in the presence of potassium hydroxide and potassium carbonate to obtain 2-methyl-S -(1-methyl-i II-pyrazol-4-yl)-2/i-tetrazo]e; chlorinating the 2-methyl-5-( 1-methyl-lII-pyrazol-4-yl)-2[/-tetrazole with N- chlorosueeinimide, in the presence acetonitrile, to obtain 5-(5-chloro-1-methyl-I H-pyrazol-4-yl)-2-mcthyl-211-tetrazole.

treating the 5-(5 -ehloro-1-methyl-I fJ-pyrazo Ie-4-yl)-2-methyl-2H-tetrazole with benzyl thiol in the presence oF N,N-dirnelhyllormamide and sodium hydride to obtain compound 5-(S-(benzylthio)-I -methy]-I [-pyrazol -4-yI)-2-methyl-2H-tetrazole of formula I, wherein R1 is -SCH2Ph, /

N N

Formula I treating the compound S-(5-(benzylthio)-1 -methyl-lII-pyrazol-4-y])-2-methyl-2f1-tetrazole with aqueous acetic acid and chlorine gas or sodium hypoehlorite in presence of hydrochloric acid in chlorinated solvents such as dichioroniethane, 1,2-dichloroethane or with aqueous acetic acid and N-chlorosuccinimide or hydrogen peroxide in presence of hydroch]oric acid in aqueous cyclic ether such as tetrahydrofuran, 1,4-dioxane, to obtain 1-rnethyl-4-(2-methyl-2H-tetrazol-5-yl)-1H-pyrazole-5-sulfonyl chloride; converting the 1 -methvl-4-(2-methyl-2H-tetrazol-5-yi)-IH-pvrazole-5-sulfonyl chloride to 1-methy1-4-(-methy1-2iI-tctrazo1-5-yl)-1iI-pyrazo1e-5-su1fonaniide in the presence of aqueous ammonia and i,2-dichloroethane; and treating the I -rnethyl-4-(2-niethyl-2H-Letrazol-5-yl)-lff-pyrazole-5-sulfonarnide with phenyl (4,6-dimethoxypyrimidin-2-yl)carbamate in the presence of triethylarnine and acetonitrile to obtain azimsulfuron or its salts, isomers, and other derivatives thereof.

Yet another embodiment of present disclosure provides a process for preparation of azimsulfuron or its salts, isomers, and other derivatives thereof, comprising: treating 1-methyl-I J-J-pyrazole with iodine and hydrogen peroxide in aqueous medium to obtain 4-iodo-i-rnethyl-1H-pyrazole; treating the 4-iodo-1-methyl-1H-pyrazole with potassium ferrocyanide and palladium (II) acetate in the presence of sodium carbonate, and N,N-dimethylacetamide, to obtain 1-methyl-1H-pyrazole-4-carbonitrile; treating the i-methyl-I 1i-pyrazole-4-carbonitrile with sodium azide and either th tri-n-butyl tin chloride in the presence of toluene, or ammoniurn chloride in the presence of N,N-dimethylformamide to obtain 5-(1 -inethyl-1H-pyrazol-4-yl)-211-tcfrazole; reacting the 5-(i-methyl-1H-pyrazoie-4-yl)-2H-tetrazole with methyl iodide or diniethyl sulphate, in the presence of potassiun hydroxide or potassium carbonate to obLain 2-methyl-5-( 1-methyl-i H-pyrazol-4-yl)-211-tetrazole; chlorinating the 2-methyi-5-(1 -methyl-1H-pyrazol-4-yl)-2H-tetrazole with N- chlorosuccinimide, in the presencc acetonitrile, to obtain 5-(5-chloro-1-methyl-1H-pyrazol-4-yl)-2-methyi-2H-teirazole; treating the 5-(5-chloro--methyl-IH-pyrazole-4-yl)-2-methyl-2H-tetrazole with sodium hydrosulfide in the presence of a N,N-dimethylformamide to obtain the compounds (1-rnethyl-4-(2-methyl-2H-tetrazol-5-yl)-1H-pyrazole-5-thiol). or its disulfide (1,2-his-C -methyl-4-(2-methyi-2/J-tctrazol-5-yl)-IH-pyrazoi-5-yi)disulfane), or mixture thereof; treating the (1 -methyl-4-(2-methyl-21-/-tetrazol-5-yl)-1 //-pyrazole-5-thioi), or its disulflde (1,2-bis-(1 -methyl-4-(2-methvl-2H-tetrazol-5-yi)-tH-pyrazol-5-yl)disulfane), or mixture thereof, with aqueous acetic acid and chlorine gas or sodium hypochlorite in presence of hydrochloric acid in chlorinated solvents such as dichloromethane, 1,2-dichloroethane or with aqueous acetic acid and N-chlorosuccinirnide or hydrogen peroxide in presence of hydrochloric acid in aqueous cyclic ether such as tetrahydrofuran, I,4-dioxane, to obtain I -methyi-4-(2-methvl-21-1-tetrazoi-5-yl)-1H-pyrazoie-5-sulfonyl chloride; converting the l-methyl-4-(2-methyl-2H-tetrazol-5-yl)-1H-pyrazole-5-sulfonyl chloride to I -methyl-4-(2-methyl-2J1-tetrazol-5-yl)-I fI-pyrazole-5-sulfonamide in the presence of aqueous ammonia and I,2-dichloroethane; and treating the 1 -methyl-4-(2-methyl-21f-tetrazol-5-yl)-l H-pyrazole-5-sulfonamide with phenyl (4,6-dimethoxypyrimidin-2-yl)carbamate in the presence of triethylamine and aeetonitrile to obtain azimsulfuron or its salts, isomers, and other derivatives thereof.

The compound azimsulfttron or its salts, isomers, and other derivatives thereof can be prepared as described above in detail; is outlined in the reaction schemes as described

hereinafter, and the description thereof

Scheme 1: General route in accordance with the present disclosure for the preparation of azimsulfuron or its salts, isomers, and other derivatives thereof:

N I / / \\

* -1T1?:I-(; N NN\ \\ / N-N J4J Iai / NH, ________ NyJ1Nj6O

NNN Q H H

Azimsutfuron (V) 1 -methyl4-(2-rnethyL2H-tetrazol-5yl)-1H-pyrwzo1e-5-sulfony1 chloride (III) is prepared from reaction of the compound (1 -methyl-4-(2-methyl-21-J-tetrazol-5-yl)-I H- pyrazole-5-thiol) (Ia), or its disulfide (1.2-bis-(I -meihyl-4-(2-methyl-2H-tetrazol-5-yfl-1H-pyrazol-5-yl)disulfane) (Tb), or mixture thereof; with aqueous acetic acid and chlorine gas or sodium hypochloritc in presence of hydrochloric acid in chlorinated solvents such as dichioromethane, 1,2-dichioroethane or with aqueous acetic acid and N-chlorosuccinimide or hydrogen peroxide in presence of hydrochloric acid in aqueous cyclic ether such as tetrahydrofuran, 1,4-dioxane Compound (TII) is converted to 1-rnethyl-4-(2-methyl-2H- tctrazol-5-yl)-1 H-pyrazole-5-sulfonamide (IV) by treatment with aqueous ammonia and 1,2-dichioroethane; and by reacting compound(IV) with phenyl (4,6-dimethoxypyTimidin-2-yl) carbamate in the presence of triethylamine and acetonitrile, the compound azimsulfuron (V) is obtaincd.

Scheme 2: General route in accordance with the present disclosure for the preparation ol' azimsulfuron or its salts, isomers, and other derivatives thereot / / / S Br! iiI)-° ci N__!N0 H2 /N N

I NJ

NNN

III lv Ic N \ cci&oc Azimsu Ifuron (s) Compound (III) is prepared from reaction of the compound 5-(5-(benzylthio)-1-methyl-f/-pyrazol-4-y])-2-methyl-2H-tetrazole of formula (Ic) with aqueous acetic acid and chlorine gas or sodium hypochiorite in presence of hydrochloric acid in chlorinated solvents such as dichloromethane, l,2-dichloroethane or with aqueous acetic acid and N-chlorosuccinimide or hydrogen peroxide in presence of hydrochloric acid in aqueous cyclic ether such as tetrahydrofuran, 1,4-dioxane. Compound (III) is converted to compound (IV) by treatment with aqueous ammonia and 1,2-dichioroethane; and further to Azimsulfuron by treating compound (IV) with phenyl(4,6-dimethoxypyrimidin-2-yI) carbarnate in the presence of triethylarnine and acetonitrile, as described in Scheme 1.

Scheme 3: General route in accordance with the present disclosure for the preparation of the intermediates (1-rnethyl-4-(2-methyl-2H-tetrazol-5-yl)-1 J-I-pyrazolc-5-thiol) (Ta), or its disulfide (1,2-bis--methyl-4-(2-methy-2Jl-tetrazol-5-yl)-1H-pyrazol-5-yl)disulfane) (Ib), or mixture thereof

N / /

N__N

7 NN N

SH \\ /

N-N Ia lb

Compound 5<5-halo-1-methyl-I ff-pyrazole-4-yl)-2-methyl-2f1-tetrazole (VT) is treated with sodium hydrosulfide in the presence of N,N-dirnethylformarnide to obtain the compound (I -methyl-4-(2-methyl-2H-teirazol-5-yl)-TH-pyrazole-5-thiol) (Ia), or its disulfide (1,2-bis-(1 -methyl-4-(2-methyl-211-tetrazol-5-yl)-lII-pyrazol-5-yl)disulfane) (Tb), or mixture thereof The reaction forms product obtained is a mixture of the desired thiol and its disulfide.

In accordance with the present disclosure, the thiol or the disulfide may be further used as a mixture or after separating from the mixture, Compound (VT) can be prepared by methylating 5-(5-halo-l-methyl-IH-pyrazol-4-yI)-2H-tetrazole (VII) with reagents such as dimethyl sulfate, methyl iodide or methyl bromide and potassium carbonate, in the presence of acetone.

NN /L N

N\ / \\ /

VII VT

In the compound @1 formula VT or VII above, X is selected from Cl, Br, or I. Compound (VI) can be also prepared by halogenating 2-methyl-5-(l -mcthyl-1H- pyrazol-4-yl)-2H-tetrazole (XIII) with reagents such as N-chlorosuccinimidc, N-bromosuccinimide, or N-iodosuccinimide in the presence of acetonitrile. / /

N-N N-N

N "N N NN \\ / \\ I

N-N N-N

N N

XIII VI

In the compound of formula VT above, X is selected from Cl, Br, or I. Scheme 4: General route in accordance with the present disclosure for the preparation of the intermediate 5-(5-(herizylthio)-1-methyl-1H-pyrazol-4-yl)-2-rncthyl-211-tetrazole (Ic). / /

/ SCH2Ph N / VI Ic Compound (VI) treated with benzyl thio in the presence of N.N-dimcthylformamide and sodium hydride yields 5-(5-(benzylthio)-l -nielhy1-lH-pyrazol-4-y)-2-mcthyl-2H-tetrazole (Ic).

In the compound of formula VI above, Xis selected from Cl, Br, or I Scheme 5: General route in accordance with the present disclosure for the preparation of azimsulfuron or its salis. isomers, and other derivatives thereof; / / / N-N N-N / / N-N &) // \ V V N-N N-N / _____ XVII N0H NAN NAN xv N-NH N-N

XVI X1 V

XIH

N-I P / N-

I N-N N-N I

SH I

N

N-I t/CI V \ /

N-N

N-N ITI

NN I N-N S\ / NN

VII I

Ia N-N I lb / I / 0 N N-N N-No *N 00 N

NNN ___________ /

N-N N-N Iv \

V

l-mcthyl-liI-pyrazole (XVII) is reacted with phosphoryl chloride in the presence of N,N-dimethylfonnarnide to yield 1-methyl-I TI-pyrazole-4-carbaidehyde (XVI), treating of 1-methyl-1H-pyrazole-4-carhaldehyde (XVI) with hydroxyl amine hydrochloride in presence of ethanol or ethyl acetate to obtain l-methyl-1H-pyrazole-4-carbaldchyde oxime (XV).

The compound 1-methyl-IH-pyrazole-4-carbaldehyde oxime (XV) is subjected to a cyclization reaction in the presence of sodium azide and N,N-dimethy[thnnamide by heating at 50-120°C, preferably 90-100°C to obtain 5-(l-methyl-lff-pyrazol-4-yI)-2JT-tetrazole (XIV).

Compound (XIV) is further converted to 2-methyI-5--methyl-I H-pyrazol-4-yl)-2H-tetrazole (XIII) by treating with a methylating reagents such as dimethyl sulfate, methyl iodide or methyl bromide and potassium carbonate, in the presence of acetone.

Halogenating the compound of formula (XIII) with a halogenating agent such as N-chlorosuccinimide, N-bromosuecinimide or N-iodosuccinimide in presence of acetonitrile, yields 5-(5halo-1 -methyl-1 H-pyrazole-4-yl)-2H-tetrazole) (VI).

Treating compound (VI) with sodium hydrosulfide in the presence of N,N- dirnethylformamidc yields the compound (I -methyl-4-(2-methyl-2H-tetrazol-5-yl)-TH- pyrazole-5-thiol) (Ta) , or its disulfidc (1,2-his-(1-methyl-4-(2-methyl-211-tetrazol-5-yl)-TH-pyrazol-5-yl) disulfane) (Ib), or mixture thereof. The thiol compound (Ia), its disulfide (Ib) or the mixtures thereof when treated with aqueous acetic acid and chlorine gas or sodium hypochlorite in presence of hydrochloric acid in chlorinated solvents such as dichloromethanc. 1,2-dichloroethane or with aqueous acetic acid and N-ehlorosuccinimide or hydrogen peroxide in presence of hydrochloric acid in aqueous cyclic ether such as tetrahydrofuran, 1,4-dioxane, yields l-methyl-4-(2-methyl-2H-tetrazol-5-yl)-I /I-pyrazole-5-sulfonyl chloride (Ill).

The compound (III) thus obtained is converted to l-methyl-4-(2-methyl-2H-tetrazol- 5-yl)-1H-pyra2ole-5-sulfonamide (IV) by treatment with aqueous ammonia and 1,2-di ehlorocthanc.

Reacting compound (TV) with phenyl (4,6-dimethoxypyrimidin-2-yl) carbarnate in the presence of triethylamine and acetonitrile results azimsulfuron (V).

In the compound of formula VT, X is selected from Cl. Br, or I. Scheme 6: General route in accordance with the present disclosure for the preparation of azimsuliutron or its salts, isomers, and other derivatives thereof; N-i / N-N" "... _OH N N

XVII CHO N

xv N-NH N-N

XIV XIII / / -5X

N NN NAN A o / \\ 1 N N

N-N N-N N-N

VI Ic iii r oxNr In the reaction scheme 5, compound 5-(5-halo-l-rnethyl-1H-pyrazole-4-yl)-2-methyl- 2H-tetrazole (VI) can also form compound 5-(5-(henzylthio)-]-mcthyl-IH-pyrazol-4-yl)-2-methyl-21-I-tetrazolc (Ic), as shown in the scheme 6 above by treating compound (VI) with benzyl thiol in the presence of N,N-dimcthylformarnide and sodium hydride.

Compound (III) or 1-methyl-4-(2-methy1-2H-tetrazol-5-y-1iI-pyrazo1e-5-su1fonyl chloride can be prepared from compound (Ic) by trcating it with aqueous acetic acid and chlorinc gas or sodium hypochlorite in presence of hydrochloric acid in chlorinatcd solvents such as dichloromethane, l.2-dichlorocthane or with aqueous acetic acid and N-chlorosuccinimide or hydrogen peroxide in prescncc of hydrochloric acid in aqueous cyclic ether such as tetrahydro luran, 1,4-dioxane.

The process as described in Scheme 5 can be followed ibr obtaining Azimsulfuron from compound Ill thus formed by scheme 6.

In the compound of formula VI, Xis selected from Cl, Br, or I. Scheme 7: General route in accordance with the present disclosure for die preparation of azimsulfuron or its salts, isomers, and other derivatives thereof CN N / / NC) (NH2 --XII XI x CN CN lx VIII / / I / _____ + NN "N-N NN /N çNYS\sy -N\I NN vu VI N-N Ia lb " Ill / V N -N C N' Nh XNIjO

C H H

IV Azimsuffuron (V) In the compound of formula VI, VII or VIII above, Xis selected from Cl, Br, or 1.

Malononitrile (XII) is reacted with triethy] orthofomiate (Xl) to yield 2- (ethoxymethylene) malononitrile CX), using acetic anhydride at a temperature in the range 105-110°C for 2 to 3 hours.

The compound 2-( thoxymethylene)malononitrile (X) is subjected to a cyclization reaction to obtain 5-amino-l-methyl-lI1-pyrazole-4-carbonitrile (IX) in the presence of N-methyl hydrazine sulfate, N-methyl hydrazine or triethyl amine and methanol, for about 1-2 hours at reflux temperature.

Compound (IX) is further converted to 5-halo-l-rnethyl-1H-pyrazole-4-carbonitrile (VIII) by treatment with a halogenating agent such as a cuprous halide selected front cuprous chloride, cuprous bromide or cuprous iodide, and sodium nitrite tn the presence of hydrochloric acid, hydrobromic acid, or sulthric acid at room temperaturc. This compound (VIII) when reacted with an optionally substituted sodium azide in presence of either ammonium halide selected from ammonium chloride, ammonium bromide or ammoniuni iodide and N,N-dimethylformamide, or a tri-n-butyl tin halide such as tri-n-butyl tin chloride, tri-n-butyl tin bromide or tri-n-hutyl tin iodide, and toluene at a temperature range from 50 to 100°C preferably at 100°C to 120°C yields the compound 5-(5-halo-l-methyl-]II-pvrazole- 4-yl)-2H-tetrazole) (VIl).

Compound (VII) is further converted to 5-(5-halo-l-methyl-1H-pyrazolc-4-yl)-2-niethyl-2H-tetrazole (VI) by treatment with a methylating such as dimethyl sulfate, methyl iodide or methyl bromide and potassium carbonate, in the presence of acetone. Treating compound (VI) with sodium hydrosulfidc in the presence of N,N-dimethylforniamide yields the compound (1-niethyl-4-(2-methyl-2H-tetrazol-5-y])-IH-pyrazole-5-thiol) (Ia) , or its disultide (I,2-his-(I (Tb), or mixture thereof. The thiol compound (Ia), its disultide (lb) or the mixtures thereof when treated with aqueous acetic acid and chlorine gas or sodium hypochiorite in presence of hydrochloric acid in chlorinated solvents such as dichioroniethane, l,2-dichloroethane or with aqueous acetic acid and N-chlorosuccinimide or hydrogen peroxide in presence of hydrochloric acid in aqueous cyclic ether such as tetrahydrofuran. I.4-dioxane, yields I -methyl-4-(2-methyl-2H-telrazoT-5-yl)-1H-pyrazole-5-sulfonyl chloride (Ill).

[he compound (III) thus obtained is converted to 1-mcthyl-4-(2-niethyl-2/J-tetrazol- 5-yl)-1H-pyrazole-5 -sulfonamide (IV) by treatment with aqueous ammonia and 1,2-dichloroeihane.

Reacting compound (IV) with phenyl (4,6-dimethoxypyrimidin-2-yl)carhamate in the presence of triethylamine and acetonitrile yields azimsulfm'on (V).

Scheme 8: General route in accordance with the present disclosure for the preparation ci azimsulfiiron or its salts, isomers, and oilier derivatives thereof; CN + CN NN _____ NC) NC 2 XII xi x

IX / /

NN N'N / _____ -NC -/*N ON +-NH I Un -vi Ic / N_N 0 I N / _SiNH2 0 SN-N(Y oXNNO Nfl1 X 7 //S N N" o 0 H H (IV) Azimsulfuron (V) In the reaction scheme 7, compound 5-(5-halo-1-methyl-I H-pyrazole-4-yI)-2-niethyl- 2H-tetrazole (VI) can also form compound 5-(5-(benzy1thio)-1-methy1-1H-pyrazo1-4-y)-2-methyl-2H-tetrazole (Ic), as sho\vn in the scheme 6 above by treating compound (VI) with benzyl thiol in the presence of N,N-dimethylformamide and sodium hydride.

Compound (III) or 1 -methyl-4-(2-methyl-2J1-tetrazol-5-yl)-1H-pyrazole-5-sulfonyl chloride can he prepared from compound (Ic) by treating it with aqueous acetic acid and chlorine gas or sodium hypochlorite in presence of hydrochloric acid in chlorinated solvents such as dichioroniethane, 1,2-dichloroethane or with aqueous acetic acid and N-chlorosuccinimidc or hydrogcn pcroxide in presence of hydrochloric acid in aqueous cyclic ether such as tetrahydrofuran, 1,4-dioxane.

The process as described in Scheme 7 can be followed for obtaining Azimsulfuron from compound lii thus formed by scheme 8.

Scheme 9: General route in accordance with thc prescnt disclosure for the preparation of azimsulfuron or its salts, isomers, and other dcrivativcs thereof; / / / N-N N-N / / N-N

CN N N NN

XVII I \\ / \\ /

XVIII N-NH N-N

XIX

XIV XIII

/ / N-I N-N N-N N-N / ci N + NN/ N-N \ / N-N J NN

N-N N

N'N TH VI / Ia N-N lb IN?2 TVN v 1-methyl-I H-pyrazo]e (XVII) is reacted with iodine in the presence of oxidizing agent in aqueous media to obtain 4-iodo-1-methyl-1H-pyrazole (XIX), Treating of 4-iodo-i-methyl-I H-pyrazole (XIX) with sodium fthocyanide in presence of palladium(II) acetate, sodium carbonate and N,N-dimethylaeetamide to obtain 1 -methyl- 1 I-I-pyrazole-4-carbonitrile (XVIII).

The compound 1-methyl-1H-pyrazole-4-carbonitrile (XVIII) is converted to 5-(1-- methyl-1H-pyrazol-4-yl)-2H-tetrazole (XIV) by treatment with sodium azide with either In-n-butyl tin chloride in the presence of toluene or ammonium chloride in presence of dirnethylformarnide by heating at 100-110°C about 10-12 hours.

The process as described in Scheme 5 can be followed for obtaining Azimsulfuron from compound (X) thus formed by scheme 9.

In the compound of formula VI. X is selected from Cl, Br, or I. Scheme 10: Genera! route in accordance with the present disclosure for the preparation of azimsulfuron or its sails, isomers, and other derivatives thereof; / N-N N-N

N-V N-V N-N

CN N NN N

XVII I \ I \\ /

XVIII N-NH N-N

XIX

Xlv XIII / / / / \\ / /

N-N N-N N-N

VI Ic III IXH2 Q:yN0 IV' V In the reaction scheme 10, compound 5-(5-halo-1-methyl-lH-pyrazole-4-yl)-2- niethyl-2!I-tctrazole (VI) can also form compound 5-(5-(henzylthio)-l-niethyl-IH-pyrazol-4-y1)-2-methy-2H-tetrazo1e (Ic), as sho in the scheme 9 above by treating compound (VI) with benzyl thiol in the presence of N,N-dimethylformamidc and sodium hydride.

Compound (111) or 1 -rnethyl-4-(2-methyl-2H-tetrazol-5-yl)-1H-pyrazole-5-sulfonyl chloride can be prepared from compound (Ic) reacted with aqueous acetic acid and chlorine gas or sodium hypochiorite in presence of hydrochloric acid in chlorinated solvents such as dichloromcthane, 1,2-dichloroethane or with aqueous acetic acid and N-chlorosuccinimide or hydrogen peroxide in presence of hydrochloric acid in aqueous cyclic ether such as tetrahydroffiran, I,4-dioxane.

The process as described in Scheme 5 can he followed for obtaining Azimsulfuron from compound 111 thus formed by scheme 10.

In the compound of formula VI, X is selected from Cl, Br, or 1.

Abbreviations The following abbreviations are employed in the examples and elsewhere herein: DMF: N,N-dimethyiforniamide, DCE: Dichlorocthanc, THF: Tetrahydrofuran.

DM5: Dirnethy! sulfate, AId3 Aluminium chloride, AlBr3: Aluminium bromide, All3: Aluminium iodide, H202: Hydrogen peroxide, Ac20: Acetic anhydride, DCM: Dichloromcthane, FIC1: Hydrochloric acid, IPA: Isopropyl alcohol, Dl water: Dc-ionized water.

DM water: Dcmineraliscd water, M/C: Moisture content, MP: Melting point, BP: Boiling point, w: weight, w/w: weight/weight

Examples

The disclosure will now be illustrated with working examples, which is intended to illustrate the working of disclosure and not intended to take restrictively to imply any limitations on the scope of the present disclosure.

Example 1: Preparation of azimsulfuron Step 1: 1-methyl-I H-pyrazole-4-carbal dehyde A mixture of phosphoryl chloride (467 gm, 3.045 moles) and IJMF were stirred for 1 hour at 0-5°C, The reaction is exothermic so temperature should be below 5°C. To this slowly added 1-methyl-Iff-pyrazole (50 gm, 0.6090 moles) and stirred for 30 mm at 0-5°C. Then slowly raised the temperature from 20-30°C to 60-70°C and stirred for 10-15 hours, Progress of the reaction was monitored by HPLC. The reaction mixture was cooled to 0-5°C, to this added ethyl acetate (250 ml), DM water (1 L) and aqueous ammonia solution (350 nil, pH-6 to 7). The reaction mixture was stirred for 1 hour at 20-30°C. The inorganic salt obtained was filtered off, washed with ethyl acetate (250 ml). The filtrate was transferred in to a separating funnel. l'he reaction mixture was allowed to settle. The organic layer was scparatcd and aqueous layer was extracted with ethyl acetate (250 ml), l'he entire organic layer was transferred to the reaction vessel, stirred for 10-15 mm and separated the final aqueous layer and organic layer. The combined organic layer having 1-methyl-I H-pyrazole-4-carbaldehyde and ethyl acetate was used as such for Step 2 without any purification or isolation at this step.

Step 2: I-methyl -lII-pyrazole-4-carhaldehyde oxime A mixture of the combined organic layer having l-methyl-IH-pyrazole-4-carbaldehyde and ethyl acetate obtained from step 1. hydroxylamine hydrochloride (63.48 gm, 0.9 135 moles) were refluxed at 70-80°C for 2-4 hours. The progress of the reaction was monitored by IIPLC. The reaction mixture was cooled to 0-5°C, to this added DM water (100 ml) and 25% aqueous ammonia solution (100 ml) at 0-5°C. The reaction mixture was stirred for 10 mm at 20-30°C. The organic layer was separated and aqueous layer was extracted with ethyl acetate (250 ml). The entire organic layer was transferred to the reaction vessel and washed with 10% brine solution (500 ml). Stirred for 10 mm and separated the final aqueous layer and organic layer. l'he organic layer was evaporated to obtain the l-methyl-1H-pyrazole-4-earbaldehyde oxime.

Dry wt: 60 grn Yield 1.2 w/w (79%) HPLC purity 99.78% Step 3: 5-( 1-methyl-1H-pyrazol-4-yl)-211-tetrazolc 1 -methyl-I fI-pvrazole-4-carbaldehyde oxime (84 gm, 0.6713 moles) obtained in step 2, ammoniurn chloride (89.77 gm, 1.6783 moics), sodium azide (109.11 gm, 1.6783 moles) were taken iii DM1" (420 ml). The reaction mixture was stirred for 10-12 hours at 110-120°C.

The progress of the reaction was monitored by HPLC. To the above reaction mixture at 0- 10°C, added DM water (500 ml). Acidify reaction mixture using dii.. HO (SN). The reaction mixture was stirred for 2 hours at 0-1 0°C, filtered the product, washed with cold DM water (200 ml) and dried the product, 5 -(1-methyl-1 H-pyrazol-4-yI)-2J1-tetrazolc at 60-70°C.

Drywt 75gm Yield: 0.89 w/w (74%) HPLC purity: 99.98% Step 4: 2-methyl-5-( I-methyl-1 l-1-pyrazol-4-yl)-2 H-tctrazolc A mixture of 5-(l-methyl-IH-pyrazol-4-yl)-2H-tetrazole (100 gm, 0.6660 moles), potassium hydroxide (74.74 gm, 1.332 moles) and acetonitrile (500 ml) were stirred for 10 mm at 20-25°C. To the above mixture added methyl iodide (378.12 gm, 2.664 moles), stirred for 10-15 hours at 20-25°C and progress of the reaction was monitored by HPLC. Excess acetonitrile was recovered at 60-70°C at reduced pressure. DCM (500 ml) and DM water (500 ml) was added to the reaction mixture, stilTed for 30 mm and the reaction mixture was kept undisturbed for 15 mm. The organic layer was separated and aqueous layer was extracted with DCM (500 ml), stirred for 1 0 nun and separated the final aqueous layer and organic layer. The organic layer was evaporated to obtain 2-methyl-5-(l-mcthyl-lH-pyrazol- 4-yl)-2H-tetrazole, or 1 -rnethyl-5-( I-methyl-11 I-pyrazol-4-yl)-2H-tetrazolc, or mixture thereof, The desired regio-isomer, 2-methyl-5-(1-methyl-IH-pyrazol-4-yl)-21I-tetrazole, was isolated by column chromatography using ethyl acetate and hexane as eluent.

Dry wt 46 gm Yield 0.46 w/w (42%) IIPLC purity 99.97 Step 5: 5-(5 -chioro-1-methyl-1H-pyrazol-4-yl)-2-mcthyl-2H-tetrazole To a solution of 2-methyl-5--methyl-I TT-pyrazol-4-yl)-2TT-tetrazole (10 gm, 0.609 moles) in acetonitrile (50 ml) was added N-chlorosuccinimide (8.22 gm, 0.0615 moles). The reaction mixture was stirred for 30 mm at 60°C. Progress of the reaction was monitored by HPLC. Excess acetonitrile was recovered at 40-50°C under reduced pressure. DI water (100 ml) was poured to the crude product at 20-25°C. The reaction mixture was stirred for 1 hours at 20-25°C, filtered the product, washed with cold DM water (50 ml) and dried the product, 5-(5-ehloro-l-methyl-1H-pyrazol-4-yl)-2-methyl-2H-tetrazole at 60-70°C.

Drywt 12gm Yield: 1.2 w/w (92%) HPLC purity: 99.5 1% MP: 124-127°C Step 6: 5-(5-(bcnzylsulfanyl)-l -methyl-I H-pyrazol-4-yl)-2-rnethyl-2L1-tetrazole.

To the above product (10gm, 0.0505 moles) obtained from step 5, DMF (30 ml), sodium hydride (60% in oil, 1.33 grn, 0.055 moles) and henzvl thiol (6.57gm, 0.053 moles) were added. The reaction mixture was stirred at 20-25°C wider nitrogen for 2 hour. Progress of the reaction was monitored by TLC. The reaction mixture was cooled to 0-10°C, added slowly DI water (200 ml). The solid product was filtered off, washed with water (50 ml). Poured hexane (100 ml) to the above crude product and stirred the suspension for 1 hour at 20-25°C. The solid product obtained was filtered off; washed with hexane (50 nil) and dried to yield the product, 5-(5-(benzylsulfanyl)-l-mcthyl-1H-pyrazol-4-yl)-2-mcthyl-2H-tetrazole at 40-45°C.

Drywt: 13gm Yield 1.3 w/w (65%) HPLC purity 99.26% Step 7: 1 -n1cthyl-4-(2-mcthyl-2H-tetrazol-5-yl)-1 [f-pyrazole-5-sulfonyl chloride To a mixture of 5-(5-(benzylsulfanyl)-l -methyl-I JI-pyrazol-4-yl)-2-rnedyl-2H-tetrazole obtained in step 6(9 gm, 0.03 14 moles), and aqueous acetic acid (10%, 50 ml) was slowly purged chlorine gas at 0-10°C. The progress of the reaction was monitored by TLC and 1-IPLC. To the reaction mixture Dl water (100 ml) was slowly, the solid obtained was filtered off, washed with water (50 ml) and dried at 60-65°C to obtain I -methyl-4-( -methyl- 211-tetrazol-5 -yl)-1 H-pyrazole-5-sulfonyl chloride.

Drywt 7.5gm Yield 0.83 w/w (91%) HPLC purity 97.65% MP 97-100°C Step 8: 1 -methyl-4-(2-rnethyl-2H-tetrazol-5-yl)-lH-pyrazole-5-sulfonamidc 1-methyl-4-(2-rncthyl-2H-tetrazol-5-yl)-1 J1-pyrazole-5-sulfonyl chloride (6.8 gm, 0026 moles) obtained in step 7, ethylene dichloride (30 ml) were taken. 25% of aqueous ammonia (7 ml, 0.133 moles) was slowly added to the reaction mixture and stirred at 20-30°C for 1-2 hours. Progress of the reaction was monitored by RPLC. The excess solvent was recovered at reduced pressure. The mixture was cooled to -5 to 0°C. Poured DT water (20 ml) to the above residue and stirred the mixture for 30 mm to 1 hour at -5 to 0°C. The solid product obtained was filtered, washed with cold DI water (70 nil) and dried at 60-65°C to obtain l-rnethvl-4-(2-methyl-21-f-tetrazol-5-vl)-IH-pyrazole-5-sulfonamidc.

Drywt 6gm Yield: 0.85 ww (96%) HPLC purity 99.89% MP: 137-139°C Step 9: Azimsulfuron A mixture of 1 -methyl-4-(2-methyl-2H-tetrazol-5-yl)-1 Ii-pyrazole-5-sulfonarnide (5.8 gm, 0.0238 moles) obtained in step 8, phenyl (4,6-dimethoxvpyrimidin-2-yl)earbarnate (7.2 gm, 0.026 moles), and triethyl amine (3.58 gin, 0.035 moles) were taken in acetonitrile (50 ml) and stirred at 20-30°C for 1 hour. Progress of the reaction mixture was monitored by HPLC. To the reaction mixture DI water (60 ml) was added, cooled the mixture to 0-10°C and slowly added cone. IICI (34-37%, 6m]) to adjust acidic pH. Stirred the reaction mixture at 20-30°C for 1-2 hour, solid product was filtered off and washed with Dl water (60 ml) and with IPA (20 ml) and dried at 60-65°C to get Azimsulfuron.

Dry wt 9.5 gin Yield: 1.64 w'w(94%) I-IPLC purity: 99.45 MP 173-176°C Example 2: Preparation of Azimsulfuron Step 1: 1-methyl-i H-pyrazole-4-carbal dchydc 1-methyl-1II-pyrazole-4-carbaldehyde was synthesized according to the method described in Step I of Example 1 Step 2: 1-methyl -1 II-pyrazole-4-carbaldehyde oxinie l-methyl-1H-pyrazole-4-carhaldehydc oximc was synthesized according to the method described in Step 2 of Example 1 Step 3: 5-( I-methyl-1 H-pyrazol -4-yl)-2H-tctrazol e 5-(l-methyl-IH-pyrazol-4-yl)-2H-tetrazole was synthesizcd according to the method described in Step 3 of Example I Step 4: 2-niethyl-5-(i-rnethyl-1II-pyrazol-4-yl)-2H-tetrazolc 2-mcthyl-5--methyL-I H-pyrazol-4-yl)-21-l-tetrazole was synthesized according to the method described in Step 4 of Example I Step 5: 5-(5 -chloro-I -methyl-I H-pyrazol-4-yl)-2-methyl-211-tetrazole 5-(5-chloro-I -methyl-lH-pyraz6l-4-yl)-2-methyl-211-tctrazole was synthesized according to the method described in Step 5 of Example I Step 6: Synthesis of (1 -methyl-4-(2-methyl-2H-tetrazol-5-yl)-1II-pyrazole-5-thiol) or (1,2-bis( 1 -methvl-4-(2-methyl-211-tetrazol-5-yl)-I H-pyrazol-5-yl)disulfane) or mixture thereof.

Fe the above 5-(5-ehloro-1-methvl-1JI-pyrazole-4-vl)-2-rnetFyl-2[I-tetrazole).

obtained from Step 5 (6 grn), added DMF (30 ml), sodium hydrosultide (8 gm). The reaction mixture was heated at 100-120°C under nitrogen for 10-14 hour. Progress of the reaction was monitored by T-IPLC. The reaction mixture was cooled to 0-10°C and slowly added dil. FIC1 (IN) to make acidic p1-I. Ethyl acetate layer was partitioned and washed with brine (10%, 30 ml). Thereafter, ethyl acetate was distilled off at 50°C at reduced pressure to obtain (1- methyl-4-(2-nicthyl-2H-tetrazol-5-yl)-1H-pyrazole-5-thiol) or (1,2-his(l -mcthyl-4-(2-methyl- 2H-tetrazol-5-yl)-I H-pyrazol -5-yl)disulfane) or mixture thereof.

Dry weight 5.5gm Yield 0.96w/w (98%) Purity 95% Step 7; l-rnethyl-4-(2-methyl-2H-tetrazol-5-yl)-I ff-pyrazolc-5-sulfonyl chloride 1 -methyl-4-(2-methyl-2H-tetrazol-5-yl)-I H-pyrazole-5-sulfonyl chloride was synthesized according to the method described in Step 7 of Example I Step 8: l-rnetliyl-4-2-methy1-2H-tetrazol-5-yl)-lH-pyrazole-5-sulfonarnide 1 -methyl-4-(2-methyl-2H-tetrazol-5-yI)-1 H-pyrazole-5-sulfonamide was synthesized according to the method described in Step 8 of Example 1 Step 9: Azimsulfuron Azimsuiftiron was synthesized according to the method described in Step 9 of

Example 1.

Example 3: Preparation of azimsulfi.iron Step 1: 2-(ethoxymcthylene)malononitrile A mixture of triethyl orthoforniate (67.3 gin, 0.454 moles) and malononitrile (20.0 gni, 0.302 moles) in acetic anhydride (77.2 gm, 0.75 moles) was refluxed for 4-5 hours at 110-140°C. The reaction was monitored by (IC. Reaction mixture was cooled to room temperature. Concentrated the reaction mixture at 70°C at reduced pressure to yield crude solid product, 2-(ethoxymethylcne)malononitrile. The crude product was thrther purified either by vacuum distillation to yield pure product, 2-(ethoxymethylene)nialnnonitrile.

Dry wt: 36.0 gm Yield 1.80 w/w(98%) HPLC purity:99% MP 65-67 °C Step 2: 5-amino-1-methyl-i H-pyrazole-4-carbonitrile A solution of 2-(ethoxymethylene)malononitrile (20.0 gm, 0.163 moles) in methanol (80.0 ml) was slowly added to a mixture of N-methyl hydrazine sulfate (23.5 gm, 0.163 moles), triethyl amine (33.0 gm. 0.326 moles) and methanol (30.0 grn). The reaction mixture was retluxed for 1-2 hour. The progress of the reaction was monitored by IT1PLC. Excess methanol was distilled out at reduced pressure. To the above residue distilled waler (40.0 ml) was added and the reaction mass was cooled to 0-15°C. 15% (w/v) aqueous sodium hydroxide solution (18.0 ml) was added to the above reaction mixture and the reaction mixture thereto was stirred for 30-45 mm at 0-5°C, filtered, washed with cold water (400 ml) and air dried to yield 5-amino-1-methyl-IH-pyrazole-4-carbonitrile at 50-75°C.

Drywt: 15.4gm Yield 0.77 w/w (77%) IIPLC purity: 98.67% MP: 216-221 °C Step 3: 5-chloro-I -methyl-lH-pyrazole-4-carbonitrilc A mixture of 5-amino-1-mcthyl-1H-pyrazolc-4-carhonitrile (12.1 gm, 0.099 moles), hydrochloric acid (72.6 ml, strength: 35-37%) in DM water (60.0 ml) was stirred at room temperature. Reaction mixture was cooled to 0 to 5°C and sodium nitrite solution (by dissolving sodium nitrite (8.2 gm, 0.119 moles) in Dl water (240 ml)) was slowly added, The reaction mixture was stirred for 1-1.5 hours at 0 to 5°C. Urea solution [prepared by dissolving urea (1.2 gm) in DI water (6.0 ml)] is added slowly to the reaction mixture. Solid cuprous chloride (12.8 gm, 0.129 moles) was added to the above reaction mixture, stirred the reaction mixture for 3-4 hours at 0 to 5°C. Then the reaction temperature was raised to room temperature and stirred for 12-18 hours. Progress of the reaction was monitored by HPLC. To the above reaction mixture was added DI water (120 ml) and 25% (w!v) aqueous sodium hydroxide solution (80.0 ml) to adjust the pH to 3-3.5. 1,2-dichloroethane was poured to the reaction mixture and stirred for 10-15 mm at 45-50°C. The inorganic salt was filtered off through hyflo bed. The organic layer was separated and aqueous layer was extracted with 1,2-dichlorocthanc, The entire organic layer was transferred to the reaction vessel and washed with 10% brine solution (50.0 ml). The organic Layer was evaporated to obtain the 5-chloro-I -methyl-I H-pyrazole-4-earbonitrile.

Drywt: 11,8gm Yield 097 W/W (84 %) IIPLC purity: 93,34% MP: 55-60°C Step 4: 5-(5 -ehioro-1-methyl-I I-I-p yrazo]e-4-yl)-2 [-tetrazole The above product, 5-chloro-1-mcthyl-IJT-pyrazole-4-carboniirile (13.0 gin, 0.092 moles), was dissolved in DMF (40 ml), followed by addition of ammonium chloride (9.9 gm, 0.184 moles) and sodium azide (12.0 gin, 0.184 moles) and stirred at 100-140°C for 10-16 hours. The progress of the reaction was monitored by IIPLC. The reaction mixture was cooled at 0-5°C and quenched with aqueous}-IC1 (78.0 ml) and stirred for 3 0-60 mm at 0-5°C.

The solid material obtained was filtered, washed with cold DM water (40 ml) and dried at 60- 65°C to yield the product, 5-(5-chloro-1-methyl-I H-pyrazole-4-yl)-2/I-tctrazolc Drywt: 16.2gm Yield 1.25 w/w (96%) l-IPLC purity: 99.26% MP:215-219°C Step 5: 5-(5-chloro-l-methyl-1H-pyrazole-4-yl)-2-methyl-2H-tetrazole), 5-(5-chloro-l -methyl-I JI-pyrazol e-4-yl)-1 -methyl-2H-tetrazole), or mixtures thereof The above product of step-4, 5-(5-chloro-1-mcthyl-lH-pyrazole-4-yl)-211-tetrazole (10.0 gm, 0.0541 moles), was dissolved in acetone (50.0 ml). Potassium carbonate (6.0 gin, 0.0433 moles) was added and stirred for about 1 hour at 20-30°C. To this mixture, slowly added a solution of DM5 (9.5 gm, 0.0757 moles) in acetone (10.0 ml) maintaining the temperature below 30°C. The reaction mixture was stirred at room temperature for about 1 hour and monitored the progress of the reaction by HPLC. The inorganic solids were filtered off Acetone was distilled off from the filtrate to obtain the crude product containing 5-(5- chloro-l -methyl-1H-pyrazole-4-yl)-2-methyl-2H-tetrazole), its rcgio-isomer, 5-(5-ehloro-1 - methyl-1H-pyrazole-4-yl)-1-methyl-2H-letrazole), or mixture thereof The desired regio-isomer, 5-(5-chloro-l -methyl-i i1-pyrazol-4-yl)-2-methvl-2H-tetrazole), was isolated by col wnn chromatography.

Drywt: 7.81 gin Yield: 0.78 w/w (73%) HPLC purity:99.12% MP: 125-127°C Step 6: 5-(5-(benzylsulfanyl)-l -methyl-I H-pyrazol-4-yl)-2-inethyl-2H-tetrazole.

Product of Step 6, 5-(5-(benzylsu1fany1)-I-methy1-lH-pvrazo1-4-y-2-methyl-2H-tetrazole was synthesized according to method described in Step-6 of Example 1.

Step 7: l-methyl-4-(2-methyl-2J!-tctrazol-5-yl)-1H-pvrazole-5-sulfonyl chloride I -methyl-4-(2-rnetl yl-2H-tetrazol-5-yl)-1 H-pyrazo le-5-sulfonyl chloride was synthesized according to the method described in Step 7 of Example 1 Step 8; 1 -rnethyl-4-(2-methyl-211-tetrazol-5 -yl)-I [I-pyrazole-5-sulfonamide I -niethyl-4-(2-methyl-2H-tetrazol-5-yl)-lII-pyrazole-5-sul fonarnide was prepared according to the method described in Step 8 of Example I. Step 9: Azimsulfuron Azimsulfuron was prepared according to the method described in Step 9 of Example 1.

Example 4: Preparation of azimsulfuron Step 1: 2-(ethoxymethylene)malononitrile The preparation of 2-(ethoxymcthylene)malononitrile was carried out in a manner similar to that described in Step 1 of Example 3.

Step 2: 5-amino-I-methyl-I If-pyrazole-4-earbonitrile The 5-amino-1-methyl-i ff-pyrazole-4-carhonitrile was synthesized according to the method described in Step 2 of Example 3.

Step 3: 5-chloro-1-methyl-IH-pyrazole-4-earbonitrile The preparation of 5-chloro-l-mcthyl-iH-pyrazole-4-earboniirile was carried out in a manner similar to thai described in Step 3 of Example 3.

Step 4: 5-(5-chloro-1-methyl-I II-pyrazole-4-yl)-211-tetrazole The preparation of 5-(5-ehloro-I -methyl-I fJ-pyrazole-4-yl)-2H-teazo1e was carried out in a manner similar to that described in Step 4 of Example 3.

Step 5: 5-(5-ehloro-1-methyl-1H-pyrazole-4-yl)-2-methyl-211-tetrazole), 5-(5-chioro-1-methyl-i H-pyrazole-4-yl)-I -mcthyl-2H-tetrazole), or mixtures thereof The 5-(5-chloro-l-methyl-1H-pyrazole-4-yl)-2-mcthyl-2H-tetrazole) or its regio-isomer 5-(5-ehloro-1 -methyl-1H-pyrazole-4-yl)-1-methyl-2H-tetrazole). or mixtures thereof were synthesized according to the method described in Step 5 of Example 3.

Step 6: Synthesis of (l-mcthyl-4-(2-methyl-2H-tetrazol-5-yl)-IH-pyTazolc-5-thiol), or its disulfide (I,2-bis-(l -methyl-4-(2-methyl-2H-tetrazol-5-yl)-I!J-pyrazol-5-yl) disulfane), or mixture thereof Synthesis of (I -methyl-4-(2-methyl-2H-tetrazo1-5-y-1 H-pyiazole-5-thiol) or (1,2-bis(1-methyl-4-(2-methyl-2H-tetrazol-5-yl)-1H-pvrazol-5-yl)disulfane) or mixture thereof was synthesized according to the method described in Step 6 of Example 2.

Step 7: 1 -rnethyl-4-(2-methyl-2H-tetrazol-5-yl)-1H-pyrazole-5-sulfonyl chloride I -methyl-4-(2-rneU yi-2f1-tetrazol-5-yl)-1 H-pyrazole-5-sulfonyl chloride was synthesized according to the method described in Step 7 of Example 1.

Step 8: 1 -methyl-4-(2-methyl-2H-tetrazol-5-yl)-1H-pyrazole-5-sulfonarnide The 1 -methyl-4-(2-methyl-2H-tetrazol-5-yl)-I H-pyrazole-5-sulfonamidc was synthesized according to the method described in Step S of Example 1.

Step 9: Azimsulfuron The preparation of azimsulfuron was carricd out in a similar manncr to that described in Step 9 of Example 1.

Exampk 5: Preparation of azimsulfuron Step 1: 2-(ethoxymethylcnc)rnalononitrilc The preparation 2-(ethoxymethylene)malononitrile was carried out in a manner similar to that described in Step I of Example 3.

Step 2: 5-amino-1-methyl-1H-pyrazolc-4-carbonitrilc Thc 5-amino-1 -nwthyl-1 H-pyrazole-4-carhonitrile was synthesized according to the above method described in Step 2 of Example 3.

Step 3: 5-brorno-1-methyl-I H-pyrazole-4-carbonitrile A mixture of 5-amino-l-methvl-1JJ-pyrazole-4-carbonitrile (20 gm, 1.63 moles) obtained from Step 2, hydrobromic acid (280 in!, strength: 48%) in DM water (605 ml) was stirred at 0 to 5°C and sodium nitrite solution (by dissolving sodium nitrite (16.94 gin, 0.245 moles) in DI water (242 ml)) was slowly added. Solid cuprous bromide (37.22 gm, 0.260 moles) was added to the above reaction mixture. stined the reaction mixture for 3-4 hours at 0 to 5°C. Then the reaction temperature was raised to room temperature and stirred for 5-8 hours. To the above reaction mixture cold DI water (1000 ml) was added at 0-5°C and stirred the resulting suspension for 1-2 hours. Progress of the reaction was monitored by HPLC. The solid product was filtered, washed with cold DI water (200 ml) and dried at 60-65°C to yield the product, 5-hroino-l-methyl-IH-pyrazole-4-carbonitrile.

Drywt:22gm Yield: 1.1 w/w (72%) HPLC purity: 99.58% MP: 90-93°C Step 4: 5-(5-hromo-1 -methyl-I H-pyrazole-4-yl)-2H-telrazole The 5-bromo-l-methyl-lH-pyrazole-4-carbonitrile (14,85 gni, 0.0798 moles), was dissolved in toluene (148 nil), and tri-n-butyl tin chloride (64.83 gm, 0.199 moles) and sodium azide (12.93 gm, 0.199 moles) was added to it. The reaction mixture was stirred at 100-145°C for 7-8 hours. The progress of the reaction was monitored by T-TPLC. The reaction mixture was cooled at 10-15°C and 10% ethanolic HC1 solution (100 ml) was added and stirred for 1-1.5 hours at 10-15°C. The inorganic salt was filtered off; washed with ethanol (30 ml). Mother liquor and washings were collected and excess of toluene and ethanol was recovered at 50-55°C at reduced pressure. Poured di-isopropyl ether (100 ml) to the above residue and stirred the resulting suspension for 1-2 hours at 20-25°C. The solid product was filtered, washed with di-isopropyl ether (30 ml) and dried at 60-65°C to yield the product, 5- (5 -bromo-1-methyl-i H-pyrazol-4-yl)-21-J-tctrazole.

Drywt:17gm Yield:1.14 w/w(93%) HPLC purity: 99.72% MP: 202-207°C Step 5: 5-(5-bromo-1 -methyl-I l-J-pyrazole-4-yl)-2-methyl-2H-tetrazole) Dissolve 5-(5-bromo-1 -methyl-1H-pyrazol-4-yl)-2H-tetrazole (Ic) (9.5 gm, 0.0414 moles) in acetonitrile (100 ml). To this mixture, potassium hydroxide (5.71 grn, 0.10 moles) and methyl iodide (24,5 gm, 0.171 moles) was added and stirred at 20-30°C for 20-25 hours.

The progress of the reaction was monitored by HPLC. The acetoniile was recovered at 55- 60°C at reduced pressure. To the above residue dichloromethane (100 ml) and Dl water (100 ml) was added and stirred the above reaction mixture for 10-15 mill at 20-25°C. The reaction mixture was allowed to settle. The organic layer was separated and aqueous layer was extracted with DCM. The entire organic layer was transferred to the reaction vessel and washed with 10% brine solution (50 ml). Stirred for 10-15 mm and separated the final aqueous layer and organic layer. ftc organic layer was evaporated to obtain the crude product. S-(5-bromo-i-methyl-lH-pyrazole-4-yl)-2-methyl-2u1-tetrazole) was obtained by puriing crude product by column chromatography by eluting ethyl acetate/ hexane (50:50) Dry wt: 5 gm Yield: 0.52 w/w (50%) IIPLC purity: 99.95% Step 6: 5-(5-(henzylsulfanyl)-I -methyl-1H-pyrazol-4-yfl-2-methyl-2H-tetrazolc.

A mixture of 5-(5-bromo-l-methyl-1H-pyrazol-4-yl)-2-incthyl-2H-tetrazole (17.7 gm, 0.072 moles), sodium hydride (2.59 grn. 0.108 moles), benzyl thiol (9.89 grn, 0.079 moles) and DMF (80 nil) was stirred at 60-80°C for 1 hour. The progress of the reaction was monitored by HPLC and TLC. The reaction mixture was cooled at 0-10°C and slowly added DI water (200 nil). The solid product was filtered ofL washed with water (50 ml and hexane (100 ml) to afforded the product, 5-(5-(benzylsulfanyl)-l-rnethyl-IH-pyrazol-4-yfl-2-methyl- 2H-tetrazole.

Drywt: 16 gm Yield 0.91 w/w(78 %) I-IPLC purity 99.43% Step 7: 1 -rnethyl-4-(2-methyl-211-tetrazol-5-yl)-1 H-pyrazole-5-sulfonyl chloride The preparation 1-methyl-4-(2-methvl-211-tetrazol-5-yl)-1H-pyrazole-5-sulfonyl chloride was carried out in a similar maimer to that described in Step 7 of Example 1.

Step 8: 1-methyl-4-(2-methyl-21f-tetrazol-5-yl)-IH-pyrazole-5-sulfonarnidc The 1 -methyl-4-(2-methyl-211-tetrazol-5-yl)-I IJ-pyrazole-5-sulfonamide was synthesized according to the method described in Step 8 of Example 1.

Step 9: Azimsulfuron The preparation of Azimsulfitron was carried out in a similar mamicr to that described in Step 9 of Example 1.

Example 6: Preparation of Azimsulfuron Step 1: 4-iodo-1-methyl-1H-pyrazole A mixture of 1-methy]-1Ji-pyrazole (7) (37 gui, 0.6090 moles), iodine (57.1 gm, 0.225 moles), hydrogen peroxide (9.2 gm, 0.27 moles) and DI water (110 ml) were stirred for 24 hour at 20-30°C. Progress of the reaction was monitored by HPLJC and TLC. The reaction mixture was coolcd to 5-10°C. The reaction mixture was quenched with 20% aqueous sodium bisuifite (100 ml) and stirred for I hour at 5-10°C. The solid product obtained was filtered off, washed with cold DI water (100 ml) and dried at 40-45°C to yield the product. 4-iodo-l-methyl-1 IJ-pyrazole Drywt: 56gm Yield: 151 w/w (60%) Step 2: 1 -methyl-i H-pyrazole-4-carbonitrile To a solution of 4-iodo-i-methyl-1H-pyrazole (55 gm, 0.264 moles) in N,N-dimethylacetamide (100 ml) was added potassium ferrocyanide (24.5 gm, 0.058 moles), palladium (11) acetate (0.592 gm, 0.0026 moles) and sodium carbonate (2798 gm, 0.264 moles). The reaction mixture was evacuated and backlilled with niliogen (3 times). The mixture was stirred for 12 hour at 90-110°C. Progress of the reaction was monitored by I-PLC. The reaction mixture was cooled to 20-30°C. to this added DI water (500 ml), ethyl acetate (500 ml) and stilTed fbr 1 hour at 20-30 °C. The reaction mixture was filtered through S pad of celite. The organic layer was separated and aqueous layer was extracted with ethyl acetate (200 ml), stirred for 15 mm and separated the final aqueous layer and organic layer.

The organic layer was washed with brine solution (200 ml). Ethyl acetate was recovered at reduced pressure at 60-70°C. The mixture was degassed for 2 hour at reduced pressure at 60- 70°C, cooled the mixture to 20-30°C. Hexane (400 ml) was added to the mixture and stirred for 1 hour at 20-30°C. The solid product obtained was filtered off, washed with cold DI water (100 ml) and dried at 40-50°C to yield the product, 1-n-iethyl-1H-pyrazole-4-carbonitrile,.

Drywt:17.94 gin Yield: 0.32 w/w (63%); Step 3: 5-( 1 -methyl-I H-pyrazol-4-yl)-211-tctrazole l-methyl-IH-pyrazole-4-carbonitrile (18 gm, 0.168 moles) obtained in step 2, fri-n-butyl tin chloride (65 gm, 0.218 moles), sodium azide (i4 gm, 0.2olmoles) were taken in toluene (180 ml). The reaction mixture was stirred for 24 hours at 11 0-1 20°C. The progress of the reaction was monitored by HPLC, The above reaction mixture was cooled to 10-15°C, to this added 10% ethanolic HCI solution (100 ml, pH 1-2). The reaction mixture was stirred for 1-1,5 hours at 10-1 5°C, filtered off the inorganic salts, washed with ethanol (30 ml). The mother [iquor and washings were collected and toluene and ethanol was recovered at 50-55°C at reduced pressure. To the above residue at 20-25°C, added di-isopropyl ether (100 ml), stirred for 1-2 hours at 20-25°C, filtered the solid, washed with di-isopropyl ether (30 ml) and dried at 60-65°C to yield the product, 5-0 -methyl-1H-pyrazol-4-yl)-2H-tetrazole.

Drywt 25gm Yield: 1.4 w/w (99%) Step 4; 2-methyl-5-(j-methyl-1H-pyrazol-4-yl)-2H-tetrazole The preparation of 2-mcthyl-5-(l -methyl-lH-pyrazol-4-yl)-2H-tetrazole was carried out in a manner simi lar to that described in Step 4 of Example 1.

Step 5: 5-(5-ehloro-1-methyl-lIJ-pyrazol-4-yl)-2-methyl-2H-tetrazole The 5-(5-chloro-1-methyl-1H-pyrazol-4-yl)-2-methyl-2H-tetrazole was synthesized according to the method described in Step 5 of Example I. Step 6: 5-(5-(benzylsulfanyl)-l -methyl-I H-pyrazol-4-yl)-2-methyl-2T1-tetrazole.

5-(5-(Benzylsulfanyl)-i-methyl-1H-pyrazol-4-yl)-2-methyl-2H-tetrazole was synthesized according to the method described in Step 5 of Example 1.

Step 7: 1 -methyl-4-(2-methyl-211-tctrazol-5-yl)-iIi-pyrazole-5-sulfonyl chloride The preparation 1 -methyl-4-(2-methyl-2H-tetrazol-5-yl)-1H-pyrazole-5-sulfonyl chloride was carried out in a similar manner to that described in Step 7 olExample 1.

Step 8: 1 -methyl-4-(2-rnethyi-2H-tetrazol-5-yl)-I ff-pyrazole-5-sulfonamidc The 1 -rnethyl-4-(2-rnethyl-2H-tetrazol-5-yl)-IH-pyrazole-5-sulfonamide was synthesized according to the method described in Step 8 of Example I. Step 9: Azimsulfuron The preparation of Azimsulthron was carried out in a similar maimer to that described in Step 9 of Example 1 Example 7: Preparation of Azimsulfuron Step 1: 4-iodo-I -methyl-I fI-pyraiolc The preparation of 4-iodo-1-mcthyl-1H-pyrazolc was carried out in a similar manner to that described in Step 1 of Example 6.

Step 2: 1-Methyl-i H-pyrazolc-4-carhonitrile The preparation of i-Methyl-1H-pyrazole-4-carbonitrile was carried out in a similar manner to that described in Stcp 2 of Example 6.

Step 3: 5-( 1-methyl-i H-pyrazol-4-yl)-2H-tctrazolc The preparation of 5-(l -methyl-IH-pyrazoi-4-yl)-2H-tetrazole was carried out in a similar maimer to that described in Step 3 of Example 6.

Step 4: 2-methyl-5-(l -methyl-i I-I-pyrazol-4-yI)-2H-tctrazolc The preparation of 2-methyl-5-Q -methyl-I H-pyrazol-4-yl)-2H-tetrazolc was carried out in a manner similar to that described in Step 4 of Example 1.

Step 5: 5-(5-ehloro-i-rncthyl-iH-pyrazol-4-yl)-2-methyl-2H-tetrazole The 5-(5-chioro-l -methyl-iH-pyrazol-4-yl)-2-methyl-2H-tetrazo[e was synthesized according to the method described in Step 5 of Example 1.

Step 6: Synthesis of (1-methyl-4-(2-methyl-211-tetrazol-S-yl)-lII-pyrazoie-5-thiol) or its disulfide (1, 2-bis-(1-methyi-4-(2-methyl-2H-ielrazol-5-yi)-lH-pyrazoi-5-yi) disulfane), or mixture thereof Synthesis of (1-methyi-4-(2-methyl-2H-tetrazol-5-yl)-iH-pyrazoic-5-thiol) or (1,2-his(l-methyl-4-(2-methyl-2H-tetrazol-5-yl)-iH-pyrazol-5-yl)disulfane) or mixture thereof was synthesized according to the method described in Step 6 of Example 2.

Step 7: 1 -methyl-4-(2-methyl-2H-tetrazoi-5-yl)-1 H-pyrazole-5-sulfonyi chloride The preparation 1 -methyl-4-(2-mcthyl-211-tetrazol-5-yl)-1lI-pyrazole-5-sulfonyl chloride was carried out in a similar maimer to that described in Step 7 of Example 1.

Step 8: 1-methyl-4-(2-methyl-2H-tetrazol-5-yl)-l f-J-pyrazole-5-sulfonamide The 1 -methyl-4-(2-methyl-2H-tetrazol-5-yl)-1H-pyrazole-5-sulfonamide was S synthesized according to the method described in Step 8 of Example 1.

Azimsulfuron prepared by the process of the present disclosure may be in the form of a white crystalline solid free from visible extraneous matter, particulate solids, and granules of varying particle size, wettable powders or dusts.

The compound can also be formulated as water soluble wettable powders (VIP), water dispersible granules (WDG), water emulsifiable granules (WEG), suspeoemulsion (SE) or oil suspension concentrate (SC). It may be applied to a field in the form of a liquid spray, or as solid powder or granules.

Although the subject matter has been described in considerable detail with reference to certain preferred embodiments thereot other embodiments are possible. As such, the spirit and scope of the present disclosure should not be limited to the description of the preferred embodiment contained therein.

Claims (1)

1. We claim: 1. A process for preparation of azimsulfuron or its salts, isomers, and other derivatives thereot comprising: treating a compound of formula I, or mixtures thereof; /N N N\IFormula I wherein, R1 is selected from -SH, -SCH2Ph, -SR or -S-SRi'; where R is a straight or a hranchcd chain C1 alkyl and R1' is a group of formula II where * denotes the point of attachment /N N.NNH

   Formula TI with aqueous acetic acid and chlorine gas or sodium liypochlorite in presence of hydrochloric acid in chlorinated solvents such as dichloromethane, I,2-dichloroethane or with aqueous acetic acid and N-chlorosuccinimidc or hydrogen peroxide in presence of hydrochloric acid in aqueous cyclic ether such as tetrahydrofuran, 1,4-dioxane to obtain l-methyl-4-(2-methyl-2H-tetrazol-5-yQ-1 H-pyrazole-5-sulfonyl chloride; converting the 1 -methyl-4-(2-methyl-2H-tetrazol-5-yl)-I /J-pyrazole-5- sulfonyl chloride to I -rnethyl-4-(2-methyl-2H-tetrazol-5-yl)-1H-pyrazole-5-sulfonamide in the presence of aqueous ammonia and a solvent selected from a chlorinated hydrocarbon. such as dichloromethane, 1,2-dichloroethane or chloroform; a cyclic ether such as tetrahydrofliran, or 1,4-dioxane; or a ketone such as acetone, ethyl methyl ketonc or methyl isobutyl ketone; and treating the 1 -methyl-4-(2-methyl-21J-tetrazol-5-yl)-1 /1-p yrazole-5-sulfonamide with phenyl (4,6-dimethoxypyrimidin-2-yl)carbamate in the presence of an organic base and a polar solvent to obtain azimsulfuron or its salts, isomers, and other derivatives thereof 2. The process as claimed in claim 1, wherein the oxidizing agent is selected from hydrogen peroxide, sodium hypochlorite, N-chlorosuccinimide or chlorine gas.

   3. l'he process as claimed in claim 1, wherein the poiar solvent is selected from N,N-dimethylformamidc, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, acetonitrile, acetone, dichioromethane, 1,2-dichlorocthanc, methanol, tetrahydrofuran, or water; and the organic base is selected from di-isopropyl ethyl amine, di-isopropyl amine, tri-n-butyl amine. tricthyl amine. trimethyl amine or pyridine.

   4 l'he process as claimed in claim 1, comprising: treating a compound of formula I, or mixture thereof /N R1 N\Formula I wherein, R1 is selected from -SH, -SCH2Ph, -SR or -S-SRi'; where R is a straight or a branched chain i alkyl and R1 is a group of formula II where * denotes the point of attachment / *NN N.N

   Formula 11 with aqueous acetic acid and chlorine gas or sodium hypochlorite in presence of hydrochloric acid in chlorinated solvents such as dichloromcthanc, 1,2-dichioroethane or with aqueous acetic acid and N-chlorosuccinimide or hydrogen peroxide in presence of hydrochloric acid in aqueous cyclic ether such as tetrahydrofuran, I,4-dioxane, to obtain 1 -rnethy1-4-(2-methyl-2H-tetrazol-5-y-1H-pra'zole-5-sulfony1 chloride; converting the 1-methyl-4-(2-methyl-2/l-tetrazol-5-yl)-1H-pyrazole-5- sulfonyl chloride to I -methyl-4-(2-rnethyl2H-tetrazo1-5-yl)-lH-pyrazole-5-sulfonamide in presence of aqueous ammonia and I,2-dichloroethane; and treating the 1 -rnethyl-4-(2-methyl-2H-tctrazol-5-yl)-l f-I-p yrazole-5-sulfonamide with phenyl (4,6-dimethoxypyrirnidin-2-yl)carbamate in the presence of triethylamine and acetonitrile to obtain azimsuiftiron or its salts, isomers, and other derivatives thereof 5, The process for preparation of azimsulthron or its salts, isomers, and other derivatives thereof, as claimed in claim 1, wherein the compound of formula I is oblained by treating a 5-(5-halo-1-methyl-I H-pyrazole-4-yl)-2-methyl-2H-tetrazole or 5-(5-halo-l-methyl-1H-pyrazole-4-yl)-l -methyl-211-tetrazole or mixture thereof with a thiol or an alkali metal hydrosulfide in presence of a solvent selected from N,N-dimethylformamide, N,N-di methylaeetarnide, N-methyl-2-pyrrolidone. aeetonitrile, acetone, tetrahydrofuran or water.

   6. The process for preparation of azimsulfuron or its salts, isomers, and other derivatives thereof, as claimed in claim 1, wherein the compound of formula I wherein R1 is selected from -SIT, or -S-SR1'; where R1' is a group of formula II where * denotes the point of attachmentI-N-NFormula 11 is obtained by treating a 5-( -halo-I -methyl-I H-pyrazole-4-yl)-2-tnethyl-2H-tetrazole with an alkali metal hydrosulfide in the presence of N,N-dimethylformamide.

   7. The process as claimed in claim 5 or 6, wherein the alkali metal hydrosulfide is selected from sodium hydrosulfldc or potassium hydrosulfidc.

   8. The process for preparation of azimsuiffiron or its salts, isomers, and other derivatives thereof, as claimed in claim 1, wherein the compound of formula 1 wherein R1 is selected from -SCI-l2Ph or -SR where R is a straight or a branched chain C1 alkyl; is obtained by treating 5-(5-halo-1 -methyl-1H-pyrazole-4-yl)-2-methyl-2H-tetrazole with a thiol in the presence of sodium hydride and N,N-dirnethylformamide.

   9. The process as claimed in claim 5 or 8, wherein the thiol is selected from C14 alkyl thiol or benzyl thiol.

   10. The process as claimed in claim 5, wherein the 5-(5-halo-I -methyl-I JI-pyrazole-4-yl)- 2-melhyl-2H-tetrazole is obtained by halogenating 2-methyl-5-(1 -methyl-1 H-pyrazol- 4-yI)-2H-tetrazole with a halogenating agent, selected from N-chlorosuccinimide, N-bromosuccinimide or N-iodosuccinimidc in the presence of a solvent selccted from N,N-dimethylformamide, N,N-dimethylaeetamide, N-inethyl-2-pyrrolidone, acetonitrile, acetone, diehloromethane, I.2-dichloroethane. methanol, tetrahydrofuran, ethyl acetate, or hutyl acetate.

   11. The process as claimed in claim 5. wherein the 5-(5-halo-I-methyl-lH-pyrazole-4-yl)- 2-methyl-2H-tetrazole, or 5-(5-halo-l -methyl-I H-pyrazole-4-yl)-l -methyl-i H- tetrazole, or mixtures thereof is obtained by methylating a 5-(5-halo-1-methyl-IH-pyrazole-4-yl)-2H-tetrazole with a methylating agent such as dimethyl sulfate, methyl iodide or methyl bromide, in presence of a base selected from an alkali metal hydroxide base such as sodium hydroxide, potassium hydroxide or lithium hydroxide; or an alkali metal carbonate base such as sodium carbonate, sodium bicarbonate, potassium carbonate or cesium carbonate; or an organic base such as triethyl amine, di-isopropyl amine, di-isopropyl ethyl amine. pyridine, pyrrolidine or N,N-diniethyl aniline, in the presence of a polar solvent such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, aeetonitrile, acetone, dichiorornethane, 1,2-dichloroethane, methanol, tetrahydrofuran or water.

   12. The process as claimed in claim 10, wherein 2-methyl-5--methyl-I l-l-pyrazol-4-yl)- 21-1-tetrazole is obtained by: treating l-methyl-lJI-pyrazole with phosphoryl chloride in the presence of N,N-dimethylformamide, to obtain I -methyl-I J!-pvrazol e-4-earbaldehyde; treating the l-methyl-1H-pyrazole-4-carbaldehyde with hydroxylamine hydrochloride in the presence of ethanol, to obtain l-methyl-lII-pyrazole-4-carbaldehyde oxime; treating the 1-methyl-1H-pvrazole-4-carbaidehyde oxime with sodium azide in the presence of ammonium chloride and N,N-dirnethylformamide, to form 5-0-methyl-1H-pyrazol-4-yl)-2H-tetrazole; and reacting 5-(1-methyl-1H-pyrazole-4-yl)-2H-tetrazole with methyl iodide or dimethyl sulphate, in the presence of potassium hydroxide or potassium carbonate to obtain 2-rnethyl-5-(1 -methyl-iH-pyrazol-4-yl)-2H-tetrazole.

   13. The process as claimed in claim 10, wherein 2-methyl-5-(i-methyl-iI-I-pyrazol-4-yl)- 21-1-tetrazole (VII) is obtained by: treating I -methyl-I /-J-pyrazole with iodine and hydrogen peroxide in aqueous medium to obtain 4-iodo-1-methyl-i H-pyrazolc; treating the 4-iodo-1-methyl-I H-pyrazole with potassium ferrocyanide and palladium (II) acetate in the prcsence of sodium carbonate, and N,N-dimethylacetamide, to obtain 1-methyl-i H-pyrazole-4-carbonitrile; treating the 1-methyl-1H-pyrazoie-4-carbonitrile with sodium azide and either with tri-n-butyl tin chloride in the presence of toluene, or ammonium chloride in the presence of N,N-dimethyiformarnide to obtain 5-(l-methyl-1H-pyrazol-4-yl)-2H-teflzole; and reacting the 5-(1-methyl-l IJ-pyrazole-4-yl)-2J1-tetrazole with methyl iodide or dimethyl sulphate, in the presence of potassium hydroxide or potassium carbonate to obtain 2-methyi-5-( 1-methyl-1H-pyrazol-4-yl)-2H-tetrazole.

   14. The process as claimed in claim 5, wherein the 5-(5-ha!o-I -methyl-I /f-pyrazole-4-yl)- 2H-tetrazolc is obtained by: freating malononitrile with triethyl orthoformate in the presence of acetic anhydridc to obtain 2-(cthoxymethylcne)malononitrile; treating the 2-(ethoxymethylene)malononitrile with an N-methyl hydrazine sulfate or N-methyl hydrazine and a base selected from an alkali metal hydroxide base such as sodium hydroxide, potassium hydroxide or lithium hydroxide; or an alkali metal carbonate base such as sodium carbonate, sodium bicarbonate, potassium carbonate or cesium carbonate; or an organic base such as triethyl amine, di-isopropyl amine, di-isopropyi ethyl amine, pyridine, pyrrohdine or N,N-diinethyl aniline, in the presence of an alcohol such as methanol, ethanol or propanol to obtain 5-amino-i-methyl-i H-pyrazole-4-carhonitriie; halogenating the 5-amino-i-methyl-i H-pyrazole-4-carbonitrile with sodium nitrite and a cuprous halide such as cuprous chloride. cuprous bromide or cuprous iodide, with a mineral acid such as hydrochloric acid, hydrobromic acid or sulfuric acid, to obtain 5-halo-i-methyl-IH-pyrazole-4-carbonitrile; and treating the 5-halo-l-methyl-1H-pyrazole-4-carbonitrile with sodium azide in the presence of either an ammoniurn halide such as ammonium chloride, ammonium bromide or aninionium iodide, and a polar solvent such as N,N-dimethylformamide, N,N-dimcthylacctamidc, N-mcthyl-2-pyrrolidonc, 1,2-dichloroethane, tetrahydrofuran or water, or tri-n-butyl tin halide such as tri-n-butyl tin chloride, tri-n-butyl tin bromide or tri-n-hutyl tin iodide, and a non polar solvent such as toluene. xylene or bcnzcnc, to obtain 5 -(5-halo-I -mcthyl-I II-pyrazolc-4-yl)-2H-tetrazole).

   15. The process as claimed in claim 1 for preparation of a.zimsulthron or its salts, isomers, and other derivatives thereof, comprising: treating 5-(5-chloro-1 -methyl-i iJ-pyrazolc-4-yl)-2-mcthyl-211-tctrazolc with benzyl thiol in the presence of a N,N-dimethylformamide and sodium hydride to obtain compound 5-(5-(bcnzylthio)-l -methyl-i IT-pyrazol-4-yI)-2-mcthyl-211-tctrazoic of formula I, wherein R is -SCH2Ph; /NFormula I treating the compound 5-(5-(bcnzylthio)-I -methyl-] JJ-pyrazol-4-yl)-2-rnethyl- 2H-tetrazole of formula I with aqueous acetic acid and chlorine gas or sodium hypochiorite in presence of hydrochloric acid in chlorinated solvents such as dichioromethanc. 1,2-dichlorocthanc or with aqueous acetic acid and N-chlorosuccinimide or hydrogen peroxide in presence of hydrochloric acid in aqueous cyclic ether such as tetrahydrofuran. T,4-dioxane to obtain i-methyl-4-(2-nieLhyl-2H-tetrazoi-5-yl)-1iI-pyrazole-5-suifonyl chloride; converting the 1 -rncthyl-4-(2-rnethyl-2H-tetrazo!-5-yl)-I H-pyrazo!e-5- sulfonyl chloride to I -methyl-4-(2-methyl-2H-tetrazol-5-yI)-1 H-pyrazole-5-sulfonamide in the presence of aqueous ammonia and 1,2-dichioroethane; and treating the 1 -methyl-4-(2-methyl-211-tctrazol -S-yJ)-l TT-pyrazole-S-sulfonamide with phenyl (4,6-dimethoxypyrimidin-2-yl) carbamate in the presence of triethylarnine and acetonitrile to obtain azimsulftiron or its salts, isomers, and other derivatives thereof 16. The process as claimed in claim 1 for preparation of azimsulfuron or its salts, isomers, and other derivatives thereof, comprising: treating 5-(5-ehloro-1 -methyl-1H-pyrwiole-4-yl)-2-inethyl-2H-tetrazole with sodium hydrosulfidc in the presence of a N,N-dimethylforrnarnide to obtain the compounds (1 -methyl-4-(2-rnethyl-2H-tetrazol-5-yl)-1II-pyrazole-5-thio!), or its disulfidc (1,2-bis-Q -niethyl-4-(2-rnethyl-2H-tetrazol-5-vl)-1H-pyrazol-5-yI) disulfane), or mixture thereof, of the formula /N N rSHN OrN_NNN "N-NN-N NN \\ /Ntreating the (1-me.thy!-4-(2-methyl-2H-tetrazol-5-yl)-1iI-pyrazole-5-tbiol). or its disul fide (1,2-bis-( 1 -methyl-4-(2-methyl-2H-tetrazol-5-yl)-1H-pyrazol-5-yl) disulfanc), or mixture thereof, with aqueous acetic acid and chlorine gas or sodium hypochlorite in presence of hydrochloric acid in chlorinated solvents such as dichloromethane, 1,2-dichioroethane or with aqueous acetic acid and N-chiorosuccinimide or hydrogen peroxide in presence of hydrochloric acid in aqueous cyclic ether such as tetrahydrofuran, 1,4-dioxane to obtain -methyl-4-(2-methy]-2H-tetrazol-5-yl)-1 H-pyrazole-5 -sulfonyl chloride; converting the 1 -methyl-4-(2-methyl-211-tetrazok5-yl)-1H-pyrazole-5- sulfonyl chloride to 1 -methyl-4-(2-methyl-2H-tetrazol-5-vI)-I [f-pyrazole-5-sulfonamide in the presence of aqueous ammonia and 1,2-dichloroethane; and treating the 1 -incthyl-4-(2-methyl-2/I-tetrazol-5-yl)-1H-pyrazole-5-sulfonamide with phenyl (4,6-dimethoxypyrimidin-2-yl)carbarnate in the presence of triethylamine and acetonitrilc to obtain azimsutifiron or its salts, isomers, and other derivatives thereof, 17. The process as claimed in claim I thr preparation of azimsulfuron or its salts, isomers, and other derivatives thereof, comprising: chlorinating 2-methvl-5-(i -methyl-IH-pyrazole-4-yI)-2J-J-tetrazole with N- ehiorosuccinimide. in the presence aeetonitrile, to obtain 5-(5-chloro-l-rnethyl-1H-pvrazol-4-yl)-2-methyl-2H-tetrazole; treating the 5-(3-chloro-1-methyl-1H-pyrazole-4-yl)-2-methyl-211-tetrazol e with sodium hydrosulfide in the presence of a N,N-dimethylformamide to obtain the compounds (I -methyl-4-(2-methyl-2H-tetrazol-5-yl)-1JI-pyrazole-5-thiol), or its disulfide (1,2-his-C -methyl-4-(2-methyl-2H-tetrazol-5-yl)-1H-pyrazol-5-yI) disulfane), or mixture thereof, of the formula /N NSH Or N'N-N / \\N NI NN \\ /N-NNtreating the (1-methyl-4-(2-mcthyl-211-tctrazol-5-yl)-1iI-pyrazole-5-thiol), or its disulfide (1,2-bis-(1rnethy1-4-(2-methvl-2H-tetrazol-5-y1)-1H-pyrazol-5-yl) disulfane). or mixture thereof, with aqueous acetic acid and chlorine gas or sodium hypochlorite in presence of hydrochloric acid in chlorinated solvents such as dichioromethane, 1,2-dichloroeihane or with aqueous acetic acid and N-chlorosuccinirnidc or hydrogen peroxide in presence of hydrochloric acid in aqueous cyclic ether such as tetrahydroftiran 1,4-dioxane to obtain I -methyl-4-(2-mcthyl-211-tctrazol-5-yl)-1 I/-pyrazole-5-sulfonyl chloride; converting the 1 -mcthyl-4-(2-mcthy!-2H-tetrazol-5-yl)-I H-pyrazole-5- sulfonyl chloride to 1 -methyl-4-(2-methyl-2H-tetrazol-5-yl)-IH-pyrazole-5-sulfonamide in the presence of aqueous ammonia and I,2-dichloroethane; and treating the 1 -methyl-4-(2-methyl-2H-tetrazol-5-yl)-1Ii-pyrazole-5-sulfonamide with phenyl (4,6-dimethoxypyrimidin-2-yl)carbamate in the presence of triethylaminc and acetonitrile to obtain azimsulfuron or its salts, isomers, and other derivatives thereof 18. The process as claimed in claim 1 for preparation of azimsuifliron or its salts, isomers, and other derivatives thereof comprising: chlorinating 2-methyl-5-(1 -methyl-1H-pyrazole-4-yl)-2H-tetrazole with N- chlorosuccininiide, in the presence acetonitrile, to obtain 5-(5-chloro-1 -methyl-1H-pyrazol -4-yl)-2-mcthyl-211-tctrazol e; treating the 5-(5-ch1oro-l-methy!-lH-pyrazoIe-4-y-2-methyI-2fJ-tetrazole with benzyl thiol in the presence of a N,N-dimethylformamide and sodium hydride to obtain compound 5-(5-(benzylthio)-I -methyl-iH-pyrazol-4-yl)-2-methyl-2H-tctrazolc of formula I, ,whcrcin R1 is -SCH2Ph; / Formula I treating the compound 5-(5-(henzylthio)-l -methyl-1 H-pyrazol-4-yl)-2-methyl- 211-tctrazolc of formula I with aqueous acetic acid and chlorine gas or sodium hypochlorite in presence of hydrochloric acid in chlorinated solvents such as dichioromethane, 1,2-diehloroethane or with aqueous acetic acid and N-chiorosuccinirnide or hydrogen peroxide in presence of hydrochloric acid in aqueous cyclic ether such as tetrahydrofuran, 1,4-dioxane to obtain I -rnethyl-4-(2-mcthyl-2H-tetrazol-5-yl)-1H-pyrazole-5-sulfonyl chloride; converting the I -methyl-4-(2-methyl-2J1-tctrazol -5--yl)--IH-pyrazole-5- sulfonyl chloride to I -methyl-4-(2-methyl-2H-tetrazol-5-yl)-1 H-pyrazole-5-sulfonamide in the presence of aqueous ammonia and 1,2-dichioroethane; and treating the 1 -methyl-4-(2-methyl-2H-tetrazol-5-yl)-1 H-pyrazo le-5-sulfonamide with phcnyl (4,6-dimethoxypyrimidin-2-yl)carbaniate in the presence of triethytarnine and acetonitrile to obtain azimsulfuron or its salts, isomers, and other derivatives thereof 19. A process for preparation of azimsulftiron or its salts, isomers, and other derivatives thereof, comprising: methylating 5-(5-ehloro-l-methyl-IH-pyrazole-4-yl)-2H-tetrazole with a methylating agent such as dimethyl sulfate, methyl iodide or methyl bromide and potassium carbonate, in the presence of acetone to obtain 5-(5-ehloro-1 -methyl-IH- pyrazole-4-yl)-2-methyl-2H-tetrazole, or its regio-isomer 5-(5-ehloro-1-methyl-1H-pyrazole-4-yl)-1-methyl-1 H-tetrazole, or mixtures thereof; treating the 5-(5-ehloro-1-methyl-I I-I-pyTazole-4-y!)-2-methy!-2H-tetrazole, or its regio-isomer 5-(5-ehloro-1-methyl--1H-pyrazole-4-yl)-l-methyl-1IJ-tetrazole, or mixtures thereof with sodium hydrosultide in the presence of N,N- diniethylformamide to obtain the compounds (I -methyl-4-(2-methyl-211-tetrazol-5- yl)-l H-pyrazole-5-thiol), or its disulfide (1,2-bis-(l-methyl-4-(2-methyl-2H-tetrazol- 5-yl)-IH-pyrazol-5-yl) disulfane), or mixture thereof, of the formula /

   N

   SH N\i Or / \\ NyN

   N \\ /

   N Ntreating the (1-methyl -4-(2-methyl-2H-tetrazol-5-yl)-IH-pyrazole-5-thiol), or its disulfide (I,2-his-(i-methyl-4-(2-methyl-211-tetrazol-5-yl)-IH-pvrazol-5-yl) disulfane), or mixture thereoL with aqueous acetic acid and chlorine gas or sodium hypoehlorite in presence of hydrochloric acid in chlorinated solvents such as dichioromethane. 1,2-dichloroethanc or with aqueous acetic acid and N-ehiorosuecinimide or hydrogen peroxide in presence of hydrochloric acid in aqueous cyclic ether such as tetrahydroftiran, I,4-dioxane to obtain 1-methyl-4-(2-methyl-2H-tetrazol-5-yl)-IH-pyrazole-5-sulfonyl chloride; converting the 1 -methyl-4-(2-methyl-2H-tetrazol-5-yl)-1 II-pyrazole-5- sulfonyl chloride to I -rnethyl-4-(2-methyl-2H-teuazol-5 -yl)-1 H-pyrazole-5-sulfonamide in the presence of aqueous ammonia and 1,2-dichioroetLane; and treating the 1 -methyl-4-(2-methyl-2H-tetrazol-5 -yl)-I H-pyrazole-5-sulfonamide with phenyl (4,6-dimethoxypyrimidin-2-yl)carbaniate in the presence of triethylamine and acetonitrile to obtain azinisulfuron or its salts, isomers, and other derivatives thereof.

   20. A process for preparation of azimsulfuron or its salts, isomers, and other derivatives thereof, comprising: methylating 5-(5 -ehloro-1-methyl-i H-pyrazole-4-yl)-2H-tetrazole with a methylating agent such as dimethyl sulfate, methyl iodide or methyl bromide and potassium carbonate, in the presence of acetone to obtain 5-(5-chloro-i-methyl-IH- prazole-4-yl)-2-niethyl-2FI-tetrazo1e, or its regio-isomer 5-(5-chloro-I-methvl-IH-pyrazole-4-yl)-1-methyl-I H-tetrazole, or mixtures thereof: treating the 5-(5-ehloro-1-methyl-I H-pyrazoie-4-yl)-2-methyl-2H-tetrazo Ic or its regio-isorner 5-(5-chloro-l-nieifyl-l 1-J-pyrazole-4-yl)-i-methyl-2H-tetrazole or mixture thereof with beuzyl thiol in the presence of a N.N-dimethylformamide and sodium hydride to obtain compound 5-(5-(benzylthio)-I-methyl-I JT-pyrazol-4-yl)-2-methyl-2H-tetrazole of formula 1, ,wherein R1 is -SCH2Ph; /N

   Formula I treating the compound 5-(5-(henzylthio)-l -methyl-iII-pyrazol-4-yl)-2-methyl- 2H-tetrazole of fonnula I with aqueous acetic acid and chlorine gas or sodium hypochloritc in presence of hydrochloric acid in chlorinated solvents such as dichloromethane. 1,2-dichloroethanc or with aqueous acetic acid and N-chlorosuccinimide or hydrogen peroxide in presence of hydrochloric acid in aqueous cyclic ether such as tetrahydrofuran. 1,4-dioxane to obtain 1 -methyl-4-(2-methyl-21J-tetrazol-5-yl)-1H-pyrazole-5-sulfonyl chloride; converting tile 1 -methyl-4-(2-methyl-21J-tctrazol-5-yi)-1H-pyrazole-5- sulfonyl chloride to 1 -methyl-4-(2-methy1-2H-tetrazol-5-y-1 JJ-pvrazole-5-sulfonamide in the presence of aqueous ammonia and 1,2-dichloroethanc; and treating the I -methyl-4-(2-mcthyl-2H-tetrazol-5-yi)-IH-pyrazole-5-sulfonamide with phcnyl (4,6-dirnethoxypyrimidin-2-yl)carbarnatc in the presence of triethylamthe and acetonitrilc to obtain azimsulftiron or its salts, isomers, and other derivatives thereof 21. The process as claimed in claim I [or preparation of azimsulfuron or its salts, isomers, and other derivatives thereof, comprising: treating i-methyl-fJ-pyrazoie with phosphoryl chloride in the presence of N,N-dimethylformam ide, to obtain 1-methyl-i H-pyrazole-4-carbaldehyde; treating the 1-methyl-i H-pyrazo le-4-carbaldchyde with hydroxylamine hydrochloride in the presence of ethanol, to obtain a I-methyl -1H-pyrazole-4-carbaidehyde oxime; treating the i-methyl-iH-pyrazole-4-carbaldehyde oximc with sodium azide in the presence of ammonium chloride and N,N-dimethylformamide, to form 5-0 -methyl-I H-pyrazol-4-yl)-2H-tetrazole; reacting the 5 -(i-methyl-I H-pyrazole-4-yl)-2H-tctrazo Ic th methyl iodide or dirnethyi sulphate, in the presence of potassium hydroxide or potassium carbonate to obtain 2-methyl-5-( i-methyl-1H-pyrazol-4-yl)-211-tetrazole; chlorinating the 2-rnethyl-5-(l-methyl-1II-pyrazole-4-yI)-2[I-tetrazole with N- chlorosuccinimide. in the presence acetonitrile, to obtain 5-(5-chloro-l-mcthyl-1H-pyrazol -4-yl)-2-rnethyl-2H-tetrazol e; treating the 5-(5-chloro-1-methyl-1H-pyrazole-4-yl)-2-rnethyl-2H-telrazole with benzyl thiol in the presence of a N,N-dimethylfonnamide and sodium hydride to obtain compound 5-(5-(benzylthio)-1 -methyl-1H-pyrazol-4-yl)-2-methyl-2H-tetrazole of formula I, wherein R1 is -SCII2Ph; treating the compound 5 -(5-(henzylthio)-1 -methyl-IH-pyrazol-4-yl)-2-methyl- 2H-tetrazolc with aqueous acetic acid and chlorine gas or sodium hypochlorite in presence of hydrochloric acid in chlorinated solvents such as dichioromethane, 1,2-dichloroethane or with aqueous acctic acid and N-chlorosuccinimide or hydrogen peroxide in presence of hydrochloric acid in aqueous cyclic ether such as tetrahydrofuran, 1,4-dioxanc to obtain I -methyl-4-(2-methyl-2H-tetrazol-5-yl)-I H-pyrazole-5-sulfonyl chloride; converting the I -rnethyl-4-(2-methyl-2H-tetrazol-5-yl)-H-pyrazole-5- sullonyl chloride to 1-rncthyl-4-(2-rnethyl-2H-tetrazol-5-yl)-l H-pyrazole-5-sulfonamide in the presence of aqueous ammonia and l,2-dichloroethane; and treating the I -methyl-4-(2-methyl-2H-tetrazol-5-yl)-I H-pyrazole-5-sulfonamide with phenyl (4,6-dimethoxypyrimidin-2-yl)carbamate in the presence of triethylamine and acetonitrile to obtain azimsulfuron or its salts, isomers, and other derivatives thereof.

   22. The process as claimed in claim I for preparation of azimsulfuron or its salts, isomers, and other derivatives thereof, comprising: treating 1-methyl-I IJ-pyrazole with phosphoryl chloride in the presence of N,N-dirnethylformarnide. to obtain I-methyl-I/J-pyrazole-4-carbaldehyde; treating the I-methyl-1 H-pyrazole-4-carbaldehyde with hydroxylamine hydrochloride in the presence of ethanol, to obtain 1-methyl-IH-pyrazole-4-earhaldehyde oxime; treating the 1 -methyl-I 1-J-pyrazole-4-earbaldehyde oxime with sodium azide in the presence of ammonium chloride and N,N-dimethyli'ormamide. to form the 5-(I -methyl-I fI-pyrazol-4-yl)-211-tetrazole; reacting the -U -methyl-IH-pyrazole-4-yl)-2H-tetrazole with methyl iodide and dimethyl sulphate, in the presence of potassium hydroxide and potassium carbonate to obtain 2-methyl-5-(1 -methyl-1H-pyrazol-4-yl)-2H-tetrazole; chlorinating the 2-methyl-5-(l -methyl-1H-pyrazole-4-yl)-2H-tetrazole with N- chlorosuceinimide, in the presence acetonitrile, to obtain 5-(5-chloro-1-rncthyl-lff-pyrazol-4-yl)-2-methyl-2H-tetrazole; treating the 5-(5-chloro-1-methyl-IH-pyrazole-4-yl)-2-methyl-2R-tetrazole with sodium hydrosulfidc in the presence of a N,N-dimethylforrnamidc to obtain the compounds (1 -methyl-4-(2-methyl-2H-tetrazol-5-yl)-1H-pyrazole-5-thiol), or its disulfide (l,2-bis-(l-methyl-4-(2-methyl-211-telrazol-5-yl)-1H-pyrazol-5-yl) disulfane), or mixture thereof, of the formula /N N tSH OrNN / \\N NN \\ /

   NJ --Ntreating the (1 -methyl-4-(2-methyl-2H-tetrazol-5 -yl)-1 lI-pyrazolc-5-thiol), or its disulflde (1,2-bis-(l-methyl-4-(2-methyl-2H-tetrazol-5-yl)-IH-pyrazol-5-yl) disuffane). or mixture thereof, with aqueous acetic acid and chlorine gas or sodium hypochlorite in presence of hydrochloric acid in chlorinated solvents such as dichioromethane, 1,2-dichioroethane or with aqueous acetic acid and N-ehiorosuccinimide or hydrogen peroxide in presence of hydrochloric acid in aqueous cyclic ether such as tetrahydrofuran, 1,4-dioxane to obtain 1-methyl-4-(2-methyl-2H-tctrazoI-5-yl)-/I-pyrazolc-5-su1fony chloride; converting the 1 -mcthyl-4-(2-methyl-2H-tctrazol-5 -yl)-1 H-pyrazole-5- sulfonyl chloride to 1 -methyl-4-(2-methyl-2H-tetrazol-5-yl)-1H-pyrazole-5-sulfonamide in the presence of aqueous ammonia and 1,2-dichloroethane; and cating the I -methyl-4-(2-methy!-2H-tetrazol-5-yl)-1 H-pyrazole-5-sulfonamide with phenyl (4,6-dimethoxypyrimidin-2-vl)carbamate in the presence of triethylamine and acetonitrile to obtain azimsulfuron or its salts, isomers, and other derivatives thereof 23. A process for preparation of azimsulfuron or its salts, isomers, and other derivatives thereof, comprising: treating malononitrilc with triethyl orthoformate in the presence of acetic anhydride to obtain 2-(ethoxymethylene) malononitrile; treating the 2-(ethoxymethylene) malononitrile with N-methyl hydrazine sulfate or N-methyl hydrazine and triethyl amine, in the presence of methanol to obtain 5-amino-1-methyl-I lJ-pvrazole-4-carbonitrilc; chlorinating the 5-amino-1-methyl-1H-pyrazolc-4-carbonitrilc with sodium nitrite and cuprous chloride, with hydrochloric acid to obtain 5-chloro-1-rnethyl-1H-pyrazole-4-carbonitrile; treating the 5-chloro-1-methyl-1H-pyrazole-4-carbonitrilc with sodium azide in the presence of' either ammonium chloride, and N,N-dimethylformamide, or tn-n- butyl-tin chloride and toluene to obtain 5-(5-chloro-1-methyl-Iff-pyrazole-4-yfl-2H-Letrazole); methylating the 5-(5-chloro-1-methyl-1H-pyrazole-4-yl)-2H-tetrazole with a methylating agent, such as dimethyl sulfate, methyl iodide or methyl bromide and potassium carbonate, in the presence of acetone to obtain 5-(-chloro-I-mcthyl-lH- pyrazole-4-yl)-2-rnethyl-2H-tetrazole, or its regio-isomer 5-(5-chloro-1 -methyl-114-pyrazole-4-yl)-I -methyl-I 1-1-tetrazole, or mixtures thercot treating the 5-(5-chloro-1 -methyl-1II-pyrazole-4-yl)-2-methyl-211-tetrazole, or its regio-isorner 5-(5-chloro-l-methyl-1M-pyrazole-4-yl)-1-methyl-1H-tLetrazole, or mixturcs thercof with benzyl thiol in the presence of a N,N-dimethy[formamide and sodium hydride to obtain compound 5-(5-(benzylthio)-1 -methyl-1II-pyrazol-4-yl)-2-methyl-21i1-tetrazole of formula I, wherein R1 is -SCH2Ph; treating the compound 5-(5-(benzylthio)-1 -methyl-1II-pyrazol-4-yl)-2-methyl- 2H-tetrazole with aqueous acetic acid and chlorine gas or sodium hypochlorite in prcscnce of hydrochloric acid in ehlorinatcd solvcnts such as dichlorornethane, 1.2-dichloroethane or with aqueous acetic acid and N-chlorosuccinimide or hydrogen peroxide in presence of hydrochloric acid in aqueous cyclic ether such as tetrahydrofuran, 1,4-dioxanc to obtain 1 -methyl-4-(2-methyl-211-tetrazol-5 -y-l 11-pyrazole-5-sulfonyl chloride; converting the I -methyl-4-(2-methyl-2H-tetrazol-5-yl)-1 H-pyrazole-5- sulfonyl chloride to 1 -mcthyl-4-(2-rnethyl-2H-tetrazol-5-yl)-I Ibpyrazole-5-sulfonamide in the presence of aqueous ammonia and I,2-dichloroethane; and treating the 1 -methyl-4-(2-methyl-2H-tetrazol-5-yl)-1 H-pyrazole-5-sulfonamide with phenyl (4,6-dimethoxypyrirnidin-2-yl)carbamate in the presence of triethylamine and acetonitrile to obtain azimsulfuron or its salts, isomers, and other derivatives thereof.

   24. A process for preparation of azimsulfuron or its salts, isomers, and other derivatives thereof comprising: treating malononitrile with triethyl orthoformate in the presence of acetic anhydride to obtain 2-(ethoxymethylene) malononitrile; treating the 2-(ethoxymethylene) malononitrile with an N-methyl hydrazine sulfate and triethyl amine, in the presence of methanol to obtain 5-amino-i-methyl- 1 H-pyrazoie-4-carbonitrile; chlorinating the 5-amino-I-methyl-1H-pyrazole-4-carbonitrile with sodium nitrite and cuprous chloride, with hydrochloric acid to obtain 5-chloro-l-mcthyl-IH-pyrazole-4-carbonitrile; treating the 5-ehloro-1 -methvl-lH-pyrazole-4-cai-bonitrile. with sodium azide in the presence of either ammonium chloride, and N,N-dimethylformamide, or tn-n- butyl tin chloride and toluene, to obtain 5-(5-chloro-l -methyl-I 11-p yrazol e-4-yI)-211-tetrazole); methylating the 5-(5-ehloro-1 -methyl-1 fI-pyrazole-4-yi)--2H-tetrazole with dimethyl sulfate and potassium carbonate, in the presence of acetone to obtain 5-(5- chloro-1-rnethyl-IH-pyrazole-4-yl)-2-methyl-2H-tetrazole, or its regio-isomer 5-(5-chloro-l-mcthyl-lfl-pyrazole-4-yl)-I -methyl-I H-tetrazole, or mixtures thereof; treating the 5-(5-chloro-1-methyl-I H-pyrazolc-4-yl)-2-methyl-2H-tetrazole. or its regio-isorner 5-(5-ch!oro-I -methyl-lH-pyrazole-4-yl)-l-methyl-1U-tetrazole, or mixtures thereof with sodium hydrosulfide in the presence ol a N,N- dimethyl lormamide to obtain the compounds (1 -methyl-4-(2-methyl-2H-tetrazol-5- yl)-lII-pyrazole-5-thiol). or its disulfide (I,2-his-( -methyl-4-(2-methyl-2H-tetrazol- 5-yl)-1H-pyrazol-5-yl) disult'ane), or mixture thereof, of the formula /N NSH Or / \\N NNN \\ /

   Ntreating the (1 -rnethyl-4-(2-methyl-2H-tetrazol-5-yl)-I JJ-pyrazole-5-thiol). or S its disuhide (I,2-bis-(l-methyl-4-(2-methyl-2H-tctrazol-5-vl)-I JJ-pyrazol-5-yl) disulfane), or mixture thereof, with aqueous acetic acid and chlorine gas or sodium hvpochlorite in presence of' hydrochloric acid in chlorinated solvents such as dichioromethane, 1,2-dichioroethane or with aqueous acetic acid and N-chiorosuccinimide or hydrogen peroxide in presence of hydrochloric acid in aqueous cyclic ether such as tetrahydrothran, I,4-dioxanc to obtain I -methyl-4-(2-methyl-2H-tetrazol-5-y)-lII-pyrazole-5 -sul fonyl chloride; converting the I -mcthyl-4-(2-methyl-2H-tetrazol-5-yl)-I H-pyrazolc-5- sulfonyl chloride to 1-methyl-4-(2-methyl-2J1-tetrazol-5-yl)-1H-pyrazole-5-sulfonamide in the presence of aqueous ammonia and 1,2-dichloroethanc; and treating the I -methyl-4-(2-methyl-2H-tetrazol-5-yl)-IH-pyrazole-5-sulfonaniidc with phenyl (4,6-dimethoxypyrirnidi n-2-yl)carbamate in the presence of triethylamine and acctonitrile to obtain azimsulfuron or its salts, isomers, and other derivatives thereof 25. Thc process as claimed in claim 1 for preparation of azimsulftiron or its salts, isomers, and other derivativcs thereof, comprising: treating l-methyl-IH-pyrazole with iodine and hydrogen peroxide in aqueous medium to obtain 4-iodo-I -methyl-1 H-pyrazole; treating the 4-iodo-1 -methyl-1H-pyrazolc with potassium ferrocyanide and palladium (II) acetate in the presence of sodium carbonate, and N,N-dirnethylacetamide, to obtain 1-methyl-lJI-pyrazole-4-carbonitn]e; treating thc 1-methyl-I H-pyrazole-4-carbonitrile with sodium azidc and either with tri-n-butyl tin chloride in the presence of loluene, or ammonium chloride in the presence o N,N-din1ethylformamide to obtain 5-(1 -methyl-1H-pyrazol-4-yl)-2H-tetrazole; reacting the 5-( 1-methyl-1H-pyrazol-4-yl)-211-tctrazole with methyl iodide or dimethyl sulphate, in the presence of potassium hydroxide or potassium carbonate to obtain 2-methyl-5-( 1-methyl-i H-pyrazol -4-yl)-211-tetrazole; chlorinating the 2-methyl-5-(l-inethyl-1H-pyrazol-4-yl)-211-tetrazole with N- chlorosuccinimide. in the presence acetonitrile, to obtain 5-(5-chloro-1-methyl-1H-pyrazol-4--yl)2-methyl-2H-tetrazo1e; treating the 5-(S-chloro-1 -methyl-IH-pyrazolc-4-yl)-2-methyl-21/-tetrazole with benzyl thiol in the presence of N,N-dimethyiforrnarnide and sodium hydride to obtain compound 5-(5-(benzylthio)-I-methyl-I H-pyrazol-4-yl)-2-methyl-2H-tetrazolc of formula I, wherein Ri is -SCI-I2Ph: treating the compound 5-(5-(Eenzylthio)-1-methyl-1H-pyrazol-4-yi)-2-methyl- 211-tetrazole with aqueous acetic acid and chlorine gas or sodium hypochiorite in presence of hydrochloric acid in chlorinated solvents such as dichloromethane, 1,2-dichioroethane or with aqueous acetic acid and N-chlorosuccinimide or hydrogen peroxide in presence of hydrochloric acid in aqueous cyclic ether such as tetrahydroftiran, 1,4-dioxane to obtain 1 -methyl-4-(2-mcthyl-2H-tetrazol-5-vl)-1H-pyrazole-5-sulfonyl chloride; converting the l-methyl-4-(2-methyl-2/f-tctrazol-5-yi)-1H-pyrazole-5- sulfonyl chloride to 1 methyl-4-(2-methy1-2H-tetrazo1-5-y1)-I H-pyrazolc-5-sulfonamide in the presence of aqueous ammonia and I,2-dichloroethanc; and treating the 1-mcthyl-4-(2-methyl-211-tetrazol-5-yI)-I H-pyrazole-5-sulfonamide with phenyl (4,6-dimethoxypyrimidin-2-yl)carbamate in the presence of triethylarnine and acetonitrile to obtain azimsulfuron or its salts, isomers, and other derivatives thereof.

   26. The process as claimed in claim I for preparation of azimsulfijron or its salts, isomers, and other derivatives thereof, comprising: treating 1-methyl-I fI-pyrazole with iodine and hydrogen peroxide in aqueous medium to obtain 4-iodo-1-methyl-1H-pyrazole; treating the 4-iodo-i-methyl-1H-pyrazoie with potassium ferroeyanide and palladium (II) acetate in the presence of sodium carbonate, and N,N-dimethyiacetamide, to obtain 1 -methyl-i TI-pyrazole-4-earbonitrile; treating the 1-methyl-IH-pyrazole-4-carbonitrile with sodium azide and either with tri-n-butyl tin chloride in the presence of toluene, or ammonium chloride in the presence of N,N-dimethylformamide to obtain 5-(l -methyl-I H-pyrazol-4-yl)-211-tetrazole; reacting the 5-(1-methyi-1H-pyrazol-4-yl)-21-I-tetrazole with methyl iodide and dimethyl sulphate, in the presence of potassium hydroxide and potassium carbonate to obtain 2-methyl-5-(I -methyl-I iI-pyrazol-4-yl)-2H-tetrazole; chlorinating the 2-methyl-5-(1 -methyl-i H-pyrazol-4-yl)-2JJ-tetrazole th N- chiorosuccinimide, iii the presence acetonitrile, to obtain 5-(5-chloro-1-methyl-1 H-pyrazol-4-yl)-2-mcthyl-2H-tetrazol e; treating the 5-(5-chloro-1-methyl-I H-pyrazole-4-yl)-2-rnethyl-2H-tetrazole with sodium hydrosulfide in the presence of a N,N-dimethylformarnide to obtain the compounds (l-inethyl-4-(2-rneUyi-2H-ietrazol-5-yl)-i 1J-pyrazole-5-thiol), or its disulfide (l,2-bis-(I -methyl-4-(2-methyl-21[-tetrazol-5-yl)-1H-pyi'azol-5-yl) disulfane). or mixture thereof; of the formula /N _ NSH OrN-NJ * NNN-N NLN \\ /treating the (1 -rnethyl-4-(2-methyl-2H-tetrazol-5 -yl)-1 H-pyrazole-5-thiol), or its disul flde (1,2-bis-(1-methvl-4-(2-methvl-211-tetrazol-5-yl)-IH-pyrazol-5-yl) disulfane), or mixture thereof, with aqueous acetic acid and chlorine gas or sodium hypochiorite in presence of hydrochloric acid in chlorinated solvents such as dichioromethane. 1,2-dichloroethane or with aqueous acetic acid and N-chlorosuccininiidc or hydrogen peroxide in presence of hydrochloric acid in aqueous cyclic ether such as tctrahydrofuran, 1,4-dioxanc to obtain I -methyl-4-(2-methyl-2H-tctrazol-5-yl)-1 H-pyrazolc-5-sulfonyl chloride; converting the 1 -mcthyl-4-(2-methyl-2H-tetrazol-5-yl)-1H-pyrazole-5- sulfonyl chloride to I -rnethyl-4-(2-methyl-2H-tetrazol-5-yl)-I H-pyrazole-5-sulfonamide in the presence of aqucous anirnonia and 1.2-dichloroethanc; and treating the 1 -methyl-4-(2-rncthyl-2H-tetrazol-5-yl)-1H-pyrazole-5-sulfonamide with phenyl (4,6-dimethoxypyrimidin-2-yl)carbamate in the presence of triethylarnine and acetonitrile to obtain azimsul ftron or its salts, isomers, and other derivativcs thereof