SU535905A3 - Method for preparing benzimidazole derivatives - Google Patents

Description

(54) METHOD FOR PRODUCING BENZIMIDAZOLE DERIVATIVES

one

This invention relates to a process for the preparation of new benzimidazole derivatives that may be used in agriculture.

Benzimidazole derivatives are known to have pesticidal properties 1.

However, benzimidazole derivatives containing a nucleophilic substituent on the benzimidazole benzene ring were not known.

The described method of producing benzimidazole derivatives of the formula

H

w

Nv

..

R3

-halogen;

R -nitro, -Srz,

-CFjCl or -SRGH

R is cyan or lower alkylsulfonyl

Ci-C4 / and 0-3 p 0-2;

with the sum, t, ha and

is that a 1-hydroxybenzimidazole ester of the formula

15

where Y is the residue of ammonia, primary or secondary amine, R is hydrogen, chlorine, fluorine, perfluoroalkyl with Ci-Sat or a radical of the formula:

-N

where each of Z is hydrogen

or halogen, and P 0-1,

where R, R2, R and R and the sum of m, n and g have the indicated meanings;

R2-Ci 3 alkyl, Ca-C3 alkenyl, Cz-Ce, cycloalkyl, benzyl, phenethyl or tetrahydro-2-pyranyl, is reacted with ammonia, a primary or secondary amine.

The specificity of an amine is not decisive, as long as it is inherently the basis. The required basicity is, as a rule, amines with a dissociation constant

 or higher, although the reaction may proceed somewhat slower in the case of sterically hindered amines, or amines containing large groups. Thus, the corresponding puleophilic reagents used by the proposed method include: chloride, bromide, fluoride and iodide of ammonium, methyl, diethyl, n-octyl, tert.-butyl, allyl, propynyl, cyclohexyl, cyclopeptilamines , aziridine, aniline, 2-naphthyl-, 2-cyclohexylethyl-, benzyl-, / g-chlorobenzylamine, piperidine, hexahydroazepine, 1, 2, 3, 4-tetrahydroquinoline, decahydroisohioolip and decahydronaphtylamine.

It is desirable to conduct the reaction in an inert environment. Suitable solvents are lower alkyl alcohols, ethers such as diethyl ether and tetrahydrofuran, hydrocarbons and acetone. The reaction proceeds at temperatures over a wide range, for example, from O-150 ° C. Usually, however, the use of temperatures above room temperature does not give appreciable advantages. During the reaction, 1-hydroxy derivative and ammonia or amine are consumed in equimolar amounts. Separation and, if necessary, purification are carried out by well-known methods.

In some cases, the reaction product is a salt of an imidazole and a nucleophilic reagent.

YZ © NN

,

Salt can be easily converted into imidazole by known methods.

The compounds used as starting materials are obtained by reducing the compound of formula

X-oNOz

X NH-C-CFg-Ri II O

The reaction proceeds through the formation of several intermediates that are not released, but result in the formation of the desired 1-hydroxybenzimidazole derivative. Reaction conditions are not critical. However, it is preferable to take as a reducing agent 2 moles of hydrogen per 1 mole of nitroprinidine, in the presence of a small amount of a catalyst containing a noble metal, preferably palladium.

Used as starting compounds, ethers are obtained by known methods for the synthesis of hydroxy derivatives.

Most often, the ether derivatives are obtained by the reaction of the corresponding oxo compounds of the formula

OH F

Xx-mv

I

with a halide of the formula W-X, where X is a halogen, in the presence of an alkali metal carbopate or other hydrogen halide acceptor. The reaction can be carried out in an inert liquid medium. The reaction can be conducted in a wide temperature range, but preferably from -20 ° C to the boiling point, with reflux condenser. Isolation of p, if necessary, is carried out by known methods.

In the case of esters, it is sometimes more expedient to prepare by reacting the 1-hydroxy derivative with an olefin or alkyne. This is especially true for tetrahydro -2-pyranyl p vinyl ethers.

Example 1. Synthesis of 7-amino-4-nitro-2,6bis (trifluoromethyl) -benzimidazole.

3.0 g of 1-methoxy-4-nitro-2,6-bis (trifluoromethyl) benzimidazole is reacted with 2.0 g of ammonium hydroxide in ethyl alcohol. The product is separated and recrystallized from a mixture of ethyl alcohol and water. The reaction product is 7-amino-4-nitro-2,6-bis (trifluoromethyl) -bepzimidazole with m.p. 163-166 S.

Example 2. Synthesis of 4,6-dinitro-7-piperidino-2-trifluoromethylbenzimidazole.

450 mg of 1-methoxy-4,6-dinitro-2-trifluoromethylbenzimidazole and 150 mg of piperidine are stirred in methyl alcohol. An additional amount of piperidine is then added. Methyl alcohol is evaporated, water is added and the pH is adjusted to 3.0. The reaction product 4,6-dinitro-7-piperidipo-2-trifluoromethylbenzimidazole is extracted with ethyl acetate and recrystallized from ethyl alcohol-water. T. pl. 207-209 ° С, the output at the temperature is about 12%.

Claims (1)

1. A method for preparing benzimidazole derivatives of the formula  H Em Jli 41 , VCF.-R . N to where Y is the residue of ammonia, primary or secondary amine, R-hydrogen, chlorine, fluorine, perfluoroalkyl with 1-6 carbon atoms, or a radical of the formula  / Night  -n where each of Z is hydrogen or halo, and 65/7 0-1, W is halogen, R is Pitro-CPP, -eP2C1 or-SRHH-group, R is a cyano group or C- € 4-alkylsulfonyl, t is an integer O-3, n is an integer O-2, g is O or 1, and the sum of t, n and r is an integer O-3, characterized in that 1-hydroxybenzimidazole esters of the formula in which RW, R and R have the values given, and the sum of m, n and g is an integer of O-3, R is (1) alkyl with 1-3 carbon atoms, (2) alkenyl with 2-3 carbon atoms, (3) cycloalkyl with 3- 6 carbon atoms, (4) benzyl, (5) phenethyl or (6) tetrahydro-2-pyranyl, undergo the interaction iju with ammonia, a primary or secondary amine, with isolation of the desired product. The source of information taken into account in the examination: 1. Belgium patent No. 732415, cl. A 01p, 1969