BR112020007752B1 - PROCESS FOR PRODUCING HERBICIDAL PYRDAZINONE COMPOUNDS - Google Patents

Abstract

The present invention provides, inter alia, a process for producing a compound of Formula (I): wherein A1, R1, R2, R3, R4, R5 and R6 are as defined herein. The present invention further provides intermediate compounds used in said process and methods for producing said intermediate compounds.

Description

[0001] The present invention relates to a process for producing herbicidal pyridazinone compounds. Such compounds are known, for example, from WO 2012/136703 and WO2017/178582. As explained therein, such compounds are typically produced by forming an acid chloride from the corresponding pyridazinone acid and coupling it with cyclohexanedione in the presence of base. This reaction first produces an enol ester which can be rearranged to a compound of Formula (I) using a catalytic amount of cyanide source, for example acetone cyanohydrin. However, the yields obtained are not ideal for large-scale production and the use of highly toxic cyanides on a manufacturing scale is undesirable. Therefore, more efficient, alternative synthesis methods are desired.

[0002] The present invention provides an alternative carbonylative arylation process that (i) avoids the need to produce acid chloride and (ii) avoids a cyanide-catalyzed rearrangement. The synthesis of enol esters by reaction of aryl halides with cyclohexanedione and carbon monoxide in the presence of a base and palladium catalyst has been described (Negishi, E.; Liou, S.; Xu, C.; Shimoyama, I .; Makabe, H. J. Mol. Cat. A: Chem. 1999, 143, 279). However, the reaction does not proceed beyond the enol esters, which can be isolated in good yield. Surprisingly it has now been discovered that when the aryl group is replaced by a specific pyridazinone group, as present in a compound of Formula (II), the initial enol ester produced actually rearranges under the reaction conditions to form the compound of Formula (II). Formula (I) in high yields.

[0003] Thus, according to the present invention, a process for producing a compound of Formula (I) is provided: wherein R1 is selected from the group consisting of hydrogen, C1-C6 alkyl, C1-C6 haloalkyl, C1-C3 alkoxy, C1-C3 alkyl, C1-C3 alkoxy, C2-C3 alkoxy, C1-C3 alkyl, aryl, and a heteroaryl with 5 or 6 members, wherein the heteroaryl contains one to three heteroatoms each independently selected from the group consisting of oxygen, nitrogen and sulfur, and wherein the aryl and heteroaryl component may be optionally substituted; R2 is C1-C6 alkyl or C3-C6 cycloalkyl; A1 is selected from the group consisting of O, C(O) and (CR7R8); and R4, R6, R7 and R8 are each independently selected from the group consisting of hydrogen and C1-C4 alkyl; R3 and R5 are each independently selected from the group consisting of hydrogen and C1-C4 alkyl or together may form a C1-C3 alkylene chain; comprising the reaction process of a compound of Formula (II) where X is a halogen; with a compound of Formula (III) wherein A1 and R3, R4, R5 and R6 are as defined with respect to Formula (I) above; in a reaction medium comprising: (i) a palladium catalyst; (ii) a suitable phosphine ligand or phosphine ligand salt; (iii) an adequate basis; and (iv) carbon monoxide; to give a compound of Formula (I).

[0004] The C1-C6 alkyl and C1-C4 alkyl groups referred to above include, for example, methyl (Me, CH3), ethyl (Et, C2H5), n-propyl (n-Pr), isopropyl (i-Pr) , n-butyl (n-Bu), isobutyl (i-Bu), sec-butyl and tert-butyl (t-Bu).

[0005] Halogen (or halo) include fluorine, chlorine, bromine and iodine.

[0006] C1-C6 haloalkyl includes, for example, fluoromethyl-, difluoromethyl-, trifluoromethyl-, chloromethyl-, dichloromethyl-, trichloromethyl-, 2,2,2-trifluoroethyl-, 2-fluoroethyl-, 2-chloroethyl-, pentafluoroethyl -, 1,1-difluoro-2,2,2-trichloroethyl-, 2,2,3,3-tetrafluoroethyl-, 2,2,2-trichloroethyl-, heptafluoro-n-propyl and perfluoro-n-hexyl. C1C4 haloalkyl includes, for example, fluoromethyl-, difluoromethyl-, trifluoromethyl-, chloromethyl-, dichloromethyl-, trichloromethyl-, 2,2,2-trifluoroethyl-, 2-fluoroethyl-, 2-chloroethyl-, pentafluoroethyl-, 1,1 -difluoro-2,2,2-trichloroethyl-, 2,2,3,3-tetrafluoroethyl-, 2,2,2-trichloroethyl- and heptafluoro-n-propyl-. Preferred C1-C6 haloalkyl groups are fluoroalkyl groups, especially difluoroalkyl and trifluoroalkyl groups, for example difluoromethyl and trifluoromethyl.

[0007] C3-C6 cycloalkyl groups include, for example, cyclopropyl, cyclobutyl, cyclopentyl and cyclohexyl.

[0008] C1-C3 alkoxyC1-C3alkyl- includes, for example, methoxymethyl, methoxyethyl, ethoxymethyl, ethoxyethyl, n-propoxymethyl, n-propoxyethyl, isopropoxymethyl or isopropoxyethyl.

[0009] C1-C3 alkoxyC2-C3alkoxyC1-C3alkyl- includes, for example, methoxyethoxymethyl-.

[0010] Nitro, as used here, refers to the -NO2 group.

[0011] Aryl, as used herein, refers to an unsaturated aromatic carbocyclic group of 6 to 10 carbon atoms having a single ring (e.g., phenyl) or multiple condensed (fused) rings, at least one of which is aromatic (e.g. indanyl, naphthyl). Preferred aryl groups include phenyl, naphthyl and the like. Most preferably, an aryl group is a phenyl group. The phenyl ring may be unsubstituted or in mono- or poly-substituted form, in which case the substituents may, as desired, be in the ortho, meta and/or para position(s).

[0012] A 5- or 6-membered heteroaryl group, in which the heteroaryl contains one to three heteroatoms each independently selected from the group consisting of oxygen, nitrogen and sulfur includes, for example, furanyl, thiophenyl, thiazolyl, oxazolyl, isoxazolyl, thiazolyl , pyrazolyl, isothiazolyl, pyridyl, pyridazinyl, pyrazinyl, pyrimidinyl and triazolyl. The heteroaryl component may optionally be mono- or polysubstituted as described.

[0013] Where the aryl or heteroaryl components described above are substituted, the one or more substituents are preferably selected from the group consisting of halo, C1-C4 alkyl, C1-C4 haloalkyl, C1-C3 alkoxy, cyano and nitro.

[0014] In one embodiment of the present invention, R1 is an optionally substituted heteroaryl.

[0015] In another embodiment of the present invention, R1 is an optionally substituted phenyl, preferably 3,4-dimethoxyphenyl.

[0016] In one embodiment of the present invention, R2 is methyl.

[0017] In a particularly preferred embodiment of the present invention, R1 is 3,4-dimethoxyphenyl and R2 is methyl.

[0018] In a preferred embodiment of the invention, X is Br or Cl, most preferably Br.

[0019] In one embodiment of the present invention, A1 is CR7R8 and R3, R4, R5, R6, R7 and R8 are hydrogen. Thus, in a particularly preferred embodiment of the present invention, the compound of Formula (III) is cyclohexanedione.

[0020] In one embodiment of the present invention, A1 is CR7R8 and R4, R6, R7 and R8 are hydrogen and R3 and R5 together form an ethylene chain.

[0021] In a particularly preferred embodiment of the present invention, A1 is CR7R8 and R3, R4, R5, R6, R7 and R8 are hydrogen, R1 is 3,4-dimethoxyphenyl and R2 is methyl.

[0022] Suitable palladium catalysts (i) include, but are not limited to, Pd(OAc)2, PdCl2, Pd/C, PdBr2, PdCl2(PhCN)2, Pd2dba2, Pd(PPh3)4 and PdCl2(cinnamyl) two. The most preferred catalyst is Pd(OAc)2. The amount of palladium catalyst is between 0.0001 and 0.05 equivalents, more preferably between 0.0001 and 0.001 equivalents.

[0023] Suitable phosphine ligand or phosphine ligand salts (ii) include, but are not limited to, monodentate phosphines such as Ph3P, Cy3P, nBuPAd2, tBu3P.HBF4 and XPhos as well as bidentate ligands such as Xantphos, Josiphos, DPEPhos, dcpb, dcpp and BINAP. The most preferred phosphine ligands are Xantphos and DPEPhos when X = Br and dcpb when X = Cl. The amount of phosphine ligands is between 0.0001 and 0.05 equivalents, more preferably between 0.0001 and 0.001 equivalents.

[0024] Suitable bases (iii) include, but are not limited to, inorganic bases such as K2CO3, Cs2CO3, Na2CO3, NaOH as well as amine bases such as triethylamine, diisopropylethylamine and DBU. The most preferred bases are triethylamine and diisopropylethylamine.

[0025] The process of the present invention is conducted in the presence of carbon monoxide, typically under a carbon monoxide atmosphere. The pressure is from 1 to 50 bar, more preferably between 2 and 10 bar. Alternatively, carbon monoxide may be generated during the process using a suitable carbon monoxide generator or precursor.

[0026] In a preferred embodiment of the present invention, the reaction medium additionally comprises a solvent (v). Suitable solvents include, but are not limited to, polar aprotic solvents such as acetonitrile, anisole, dioxane, THF, EtOAc, MTBE, PrCN. The most preferred solvent is acetonitrile.

[0027] A compound of Formula (IIa) is additionally provided wherein R1a is an optionally substituted phenyl and R2 and X are as defined above.

[0028] A compound of Formula (IIa1) is additionally provided wherein R2 and en = 0, 1, 2 or 3.

[0029] The present invention further provides a compound of Formula (IIa), wherein R2 is methyl, -6-methyl-pyridazin-3-one/a compound of Formula (IIa1a)).

[0030] The following scheme describes the reactions of the invention in more detail. The definitions of the substituents are the same as defined above. Scheme 1

[0031] Typically small amounts of the enol ester of Formula (VIII) are continuously generated in the presence of the large effective excess of cyclohexanedione and base.

Step (a):

[0032] Compounds of Formula (II) can be prepared by reacting a pyridazinone of Formula (IX) wherein R2 is as defined above for the compound of Formula (I) with a boronic acid of Formula (IV) wherein R1 is as defined above for the compound of Formula (I) in the presence of a base, a copper catalyst and oxygen as for example described in Monnier, F.; Tailefer, M. Topics in Organomet. Chem. 2013, 46, 173.

[0033] Suitable copper catalysts include, but are not limited to, CuCl, CuBr, CuI, Cu(OAc)2 and Cu2O. The most preferred catalyst is Cu(OAc)2.

[0034] Suitable bases include, but are not limited to, alkali metal hydroxides and carbonates such as NaOH, KOH, K2CO3 and Na2CO3 as well as amine bases such as Et3N, iPr2NEt and pyridine. The most preferred bases are pyridine and Na2CO3.

[0035] The reactions between the compounds of Formulas (IX) and (IV) are preferably carried out in the presence of a solvent. Suitable solvents include, but are not limited to, organic solvents such as DMF, 1,2-dichloroethane, acetonitrile, EtOAc, iPrOAc, dimethylacetamide, sulfolane and NMP. The most preferred solvents are DMF, dimethylacetamide and NMP.

[0036] The reaction can be carried out at a temperature of 25 °C to 120 °C, more preferably 40 °C to 80 °C.

[0037] Preferably, the reaction is operated while continuously purging with an oxygen/nitrogen mixture. The oxygen concentration can be from 5 to 100%, preferably between 5 and 25%, more preferably 22% (air).

Step (b):

[0038] Alternatively, compounds of Formula (II) can be prepared by pyridazinone reaction of formula (IX) wherein R2 is as defined above for the compound of Formula (I) and X is a chlorine, bromine or iodine with a compound of Formula (VII) R1-I (VII) wherein R1 is selected from the group consisting of C1-alkyl C6, C1-C6 haloalkyl, C1-C3 alkoxy, C1-C3 alkyl, C1-C3 alkoxy, C2-C3 alkoxy, C1-C3 alkyl, C1C6 haloalkyl, C2-C6 haloalkenyl, C1-C3 alkoxy-C1 haloalkyl C3 in the presence of a base.

Step (c):

[0039] Alternatively, the compounds of Formula (II) wherein X is chlorine, R1 is aryl and a 5- or 6-membered heteroaryl, wherein the heteroaryl contains one to three heteroatoms each independently selected from the group consisting of oxygen, nitrogen and sulfur, and wherein the aryl and heteroaryl component may be optionally substituted by one or more substituents selected from the group consisting of halo, C1-C3 alkyl, C1-C3 haloalkyl, C1-C3 alkoxy, cyano, acetylamino, nitro and R2 is C1-C6 alkyl or C3-C6 cycloalkyl can be prepared by aldehyde reaction of Formula (VI) wherein R1 is aryl and a 5- or 6-membered heteroaryl, wherein the heteroaryl contains one to three heteroatoms each independently selected from the group consisting of oxygen, nitrogen and sulfur, and wherein the aryl and heteroaryl component may be optionally substituted by one or more substituents selected from the group consisting of halo, C1-C3 alkyl, C1-C3 haloalkyl, C1-C3 alkoxy, cyano, acetylamino, nitro with a phosphonate of Formula (V) where X is chlorine and R9 is C1-C3 alkyl in the presence of a base and an alcoholic solvent.

[0040] Suitable bases include, but are not limited to, alkali metal alkoxides such as NaOEt, NaOMe, KOtBu and NaOtBu.

[0041] A suitable alcoholic solvent includes, but is not limited to, MeOH, EtOH, iPrOH and tBuOH.

[0042] The reaction can be carried out at a temperature of -25 °C to 40 °C, preferably from 0 °C to 20 °C.

[0043] Alternatively, compounds of Formula (II) in which R1 is 3,4-dimethoxyphenyl and R2 is as defined in Formula (I) and X is Br can be prepared by a process comprising reaction of a compound of Formula ( IX) with a halogenating agent to provide a compound of Formula (X) wherein X is Br and R9 is selected from the group Br and I, preferably Cl; and then reacting a compound of Formula (X) with a compound of Formula (XI) in the presence of a radical initiator and base or by irradiating the reaction mixture with visible light in the presence of a suitable sensitizer and base.

[0044] Suitable halogenants (chlorinating agents) include sodium hypochlorite, t-butyl hypochlorite and other alkyl hypochlorites, chlorine, NCS, trichloroisocyanuric acid. Sodium hypochlorite is preferred.

[0045] The initial reaction can be carried out under homogeneous conditions (with t-butyl hypochlorite) or in a two-phase system (with aq. sodium hypochlorite) and organic solvent in the presence of a neutralizing agent (acid, buffer) that is added in parallel with sodium hypochlorite solution.

[0046] Likewise, the reaction can simply be carried out in water (with sodium hypochlorite or chlorine) and the product is isolated by filtration.

[0047] Suitable solvents include chlorobenzene, dichloromethane, toluene and MTBE. Chlorobenzene and dichloromethane are preferred.

[0048] Suitable acidifying agents include mineral acids (e.g., HCl, H2SO4), carboxylic acids (e.g., AcOH), phosphate buffer, sodium bicarbonate.

[0049] The initial reaction can be carried out at a temperature of -5 °C to 80 °C, preferably 25 °C to 40 °C.

[0050] Compound (X) can be isolated in pure form by crystallization from the organic solvent used for the reaction or by simple evaporation of the organic layer. It can also be used in the subsequent reaction.

[0051] With regard to the conversion of compound (X) to compound (II), suitable solvents include toluene, chlorobenzene, 1,2-dichlorobenzene, benzonitrile, TBME, acetonitrile, butyronitrile, dichloromethane, 1,2-dichloroethane, acetate ethyl, isopropyl acetate, Chlorobenzene is preferred.

[0052] Phase transfer catalysts can also be used to improve the speed and yield of the reaction and include, for example, Bu4NCl and Aliquat 336.

[0053] Radical initiators include, but are not limited to, AIBN, benzoyl peroxide, lauroyl peroxide, bis(tert-butylcyclohexyl) peroxydicarbonate (DCHPC), tert-butyl hydroperoxide, cumene hydroperoxide (CHP ), methyl ethyl ketone peroxide (MEKP), potassium peroxodisulfate. Cumene hydroperoxide (CHP) and methyl ethyl ketone peroxide (MEKP) are preferred.

[0054] It should also be noted that the Compound of Formula (IX) can be converted into a compound of Formula (II) in a single-step procedure. Thus, compound (X) can be generated (and continuously consumed after generation) in situ, allowing the transformation of (IX) into (II) to be carried out in a single step. Likewise, stoichiometric amount of base is not necessary in this case. Typically, a sodium hypochlorite solution is added to a mixture of Compound (IX), 1,2-dimethoxybenzene, organic solvent, aqueous buffer solution, phase transfer catalyst and a radical initiator. The radical initiator can also be added simultaneously with a sodium hypochlorite solution.

[0055] Alternatively, a photochemical catalyzed procedure can be employed. Suitable bases in this regard include, but are not limited to, inorganic bases such as K2CO3, Cs2CO3, Na2CO3, NaHCO3, sodium acetate, potassium acetate, NaOH and phosphate buffer.

[0056] The reaction can be carried out at a temperature of 20 °C to 80 °C, preferably 30 °C to 40 °C.

[0057] Alternatively, the compound of formula (II) in which X = bromine and R1 = aryl (especially 3,4-dimethoxyphenyl) as defined above can be obtained from an electrolysis of pyridazinone (IX) in the presence of a compound of Formula (XI) and an electrolyte in an organic solvent. This procedure has an advantage in that it is not necessary for the reaction to proceed through an intermediate of Formula (X).

[0058] Electrolysis can be carried out in a batch-type reaction mode with a defined current passed through the reaction mixture by employing electrodes connected to a power supply device or by a flow-type reaction mode of the mixture flow. reaction through an electrolysis flow cell. The most preferred electrolysis reaction mode is flow electrolysis.

[0059] Suitable electrode materials include, but are not limited to, graphite, glassy carbon, DSA, Ir/Ta MOX, Ir/Ti MOX as the anode material and graphite, glassy carbon, steel, copper, platinum as the anode material. cathode. Preferred material is Ir/Ta MOX for the anode and steel (V2A) for the cathode.

[0060] Suitable electrolytes include, but are not limited to, salts of type A+ B- where A+ = Na+, K+, NR4+ (with R = H or alkyl), and where B- = acetate, pivalate, benzoate, fluoride. Additional electrolytes include, but are not limited to, organic electrolytes, namely, tetramethyl guanidine, DBU, triethyl amine, 4-N,N'-dimethylamino pyridine, HFIP, acetic acid. Preferred electrolytes are sodium and potassium pivalate carboxylate salts.

[0061] Suitable solvents include, but are not limited to alcohols MeOH, EtOH, iPrOH, tBuOH, HFIP with MeOH being the preferred solvent.

[0062] Electrolysis can be carried out at a temperature of -20 °C to 60 °C, preferably from 5 °C to 35 °C.

[0063] The present invention thus further provides a compound of Formula (X) wherein R9 is selected from the group consisting of Cl, Br and I, preferably Cl (ie, 4-bromo-2-chloro-6-methyl-pyridazin-3-one).

Step (d)

[0064] The compound of Formula (I) can advantageously be prepared by reacting a compound of Formula (II) with a compound of Formula (III) in the presence of a base, palladium catalyst, a suitable phosphine or phosphine salt and carbon monoxide.

[0065] Suitable bases include, but are not limited to, inorganic bases such as K2CO3, Cs2CO3, Na2CO3, NaOH as well as amine bases such as triethylamine, diisopropylethylamine and DBU. The most preferred bases are triethylamine and diisopropylethylamine.

[0066] Suitable palladium catalysts include, but are not limited to, Pd(OAc)2, PdCl2, Pd/C, PdBr2, PdCl2(PhCN)2, Pd2dba2, Pd(PPh3)4 and PdCl2(cinnamyl)2. The most preferred catalyst is Pd(OAc)2. The amount of palladium catalyst is 0.0001 to 0.05 equivalents, more preferably between 0.0005 and 0.005 equivalents.

[0067] Suitable phosphines and phosphine salts include, but are not limited to, monodentate phosphines such as Ph3P, Cy3P, nBuPAd2, tBu3P.HBF4 and XPhos as well as bidentate ligands such as Xantphos, Josiphos, Dpephos, dcpb, dcpp and BINAP. The most preferred phosphine ligands are Xantphos and Dpephos when X = Br and dcpb when X = Cl. The amount of phosphine ligands is 0.0001 to 0.05 equivalents, more preferably between 0.0005 and 0.005 equivalents.

[0068] The reaction is carried out under a carbon monoxide atmosphere. The pressure is from 1 to 50 bar, more preferably between 2 and 10 bar.

[0069] The reactions between the compound of Formula (II) and compound of Formula (III) are preferably carried out in the presence of a solvent. Suitable solvents include, but are not limited to, polar aprotic solvents such as acetonitrile, anisole, dioxane, THF, EtOAc, MTBE, PrCN. The most preferred solvent is acetonitrile.

[0070] The reaction can be carried out at a temperature of 20 °C to 120 °C, preferably 40 °C to 70 °C.

[0071] Various aspects and embodiments of the present invention will now be illustrated in more detail by way of the following non-limiting examples.

[0072] The following abbreviations are used: s = singlet; br s = wide singlet; d = doublet; dd = double doublet; dt = double triplet; t = triplet, tt = triple triplet, q = quartet, quin = quintuplet, sept = septet; m = multiplet; TR = retention time, MH+ = molecular mass of the molecular cation.

[0073] 1H NMR spectra are recorded at 400 MHz unless otherwise indicated and chemical shifts are recorded in ppm. Example 1: Preparation of 4-Bromo-2-(3,4-dimethoxyphenyl)-6-methyl-pyridazin-3-one. Example 1a: 4-Bromo-2-(3,4-dimethoxyphenyl)-6-methyl-pyridazin-3-one

[0074] To a solution of 5-bromo-3-methyl-1H-pyridazin-6-one (5.00 g, 24.9 mmol, 94% purity) in anhydrous DMF (20 mL) was added Cu(OAc )2 (1.15 g, 6.32 mmol) and pyridine (4.1 mL, 50 mmol). The resulting suspension was heated to 50 °C and a solution of 3,4-dimethoxyphenylboronic acid (7.05 g, 37.9 mmol) in anhydrous DMF (30 mL) was added over 4.5 h via a pump. of syringe. During the reaction, air was bubbled through the reaction mixture with vigorous stirring. The reaction was stirred for an additional 2 h and then cooled to room temperature. Dichloromethane (100 mL) was added followed by 1 M HCl (200 mL). The resulting mixture was stirred for 30 min, the organic layer was separated and the aqueous layer extracted with dichloromethane (2x 100 ml). The combined organic phase was washed with ice water (4x 100 mL), dried over anhydrous Na2SO4 and concentrated under reduced pressure to give 4-bromo-2-(3,4-dimethoxyphenyl)-6-methyl-pyridazin-3-one in raw (10.21 g) as a brown solid. Quantitative NMR analysis using trimethoxybenzene as an internal standard indicates 71% purity (88% yield). The crude product was suspended in TBME (50 mL) and stirred for 20 min, the TBME was decanted and the same procedure was repeated twice more. After drying, the residue under high vacuum gave 4-bromo-2-(3,4-dimethoxyphenyl)-6-methyl-pyridazin-3-one (6.30 g, 95% purity, 73% isolated yield) as a light brown solid. 1H NMR (400MHz, CDCl3): δ 7.58 (s, 3H), 7.16-7.12 (m, 2H), 6.95-6.92 (m, 1H), 3.92 (s, 3H), 3.90 (s, 3H), 2.39 (s, 3H). Example 1b - alternative route to 4-Bromo-2-(3,4-dimethoxyphenyl)-6-methyl-pyridazin-3-one. Step 1: 4-bromo-2-chloro-6-methyl-pyridazin-3-one

[0075] 5-Bromo-3-methyl-1H-pyridazin-6-one (20.0 g, 103.8 mmol, 98.1% purity), dichloromethane (60 mL) and tert-butanol (1 mL, 10.5 mmol) were charged into a reactor. Sodium hypochlorite solution (80.3 g, 116.4 mmol, 10.8%) and glacial acetic acid (6.67 g, 116.4 mmol) were added in parallel at 23-27 °C within 40 min. The mixture was diluted with dichloromethane (150 ml) and the phases were separated. The aqueous phase was extracted with dichloromethane (60 mL). The combined organic phase was dried over anhydrous Na2SO4 and the solvent was completely removed by rotary evaporation under reduced pressure to give a white crystalline material (23.17 g, 99% purity by quantitative NMR NMR analysis, mp 145-148 °C dec.). 1H NMR (400MHz, CDCl3): δ 7.54 (s, 1H), 2.35 (s, 3H). Step 2: 4-Bromo-2-(3,4-dimethoxyphenyl)-6-methyl-pyridazin-3-one

[0076] 4-Bromo-2-chloro-6-methyl-pyridazin-3-one (2.00 g, 8.9 mmol, 99% purity), 1,2-dimethoxybenzene (1.48 g, 10, 7 mmol), bis(4-tert-butylcyclohexyl)peroxydicarbonate (0.19 g, 0.48 mmol), sodium bicarbonate (1.13 g, 13.4 mmol), tetrabutylammonium chloride (52 mg, 0 .18 mmol), chlorobenzene (20 g) and water (9 g) were loaded into a flask. The mixture was heated to 60°C for 2 h. The organic phase was separated and the aqueous phase was extracted with chlorobenzene (2x 20 ml). The combined organic extract was dried over Na2SO4 and evaporated to give a brown oil (2.9 g). This material was analyzed by quantitative HPLC.

Example 1c - alternative route (one step) to 4-Bromo-2-(3,4-dimethoxyphenyl)-6-methyl-pyridazin-3-one.

[0077] 5-Bromo-3-methyl-1H-pyridazin-6-one (3.0 g, 15.0 mmol, 94.5% purity), 1,2-dimethoxybenzene (41.4 g, 300 mmol ), Aliquat® 336 (0.61 g, 1.5 mmol), chlorobenzene (47 mL) and phosphate buffer solution (38 mL, 38 mmol, 1 M, pH = 7.2) were charged into a double reactor. jacketed. A solution of sodium hypochlorite (10.6 g, 15.0 mmol, 10.6%) was added in one portion and the mixture was stirred for 10 min at RT. A solution of methyl ethyl ketone peroxide (0.99 g, 1.5 mmol, 32% in phthalate-free plasticizer mixture) in chlorobenzene (9 mL) was added simultaneously with a solution of sodium hypochlorite (58.1 g , 82.0 mmol, 10.6%) in about 3 h while maintaining the temperature at 35 °C (Addition of sodium hypochlorite solution ended 15 min earlier). During this period, 4 consecutive servings of 5-Bromo-3-methyl-1H-pyridazin-6-one (each serving 3.0 g, 15.0 mmol, 94.5% purity; totally 12.0 g, 65 .0 mmol) were added with 40 min intervals between each portion. The reaction mixture was stirred for 1 h at 35°C. Reactive active chlorine was destroyed with sodium metabisulfite solution (5 mL, 10%). The mixture was heated to 80°C and the lower aqueous layer was separated. The solvent and the residual amount of 1,2-dimethoxybenzene were removed by vacuum distillation. The hot product melt was diluted with 1-Butanol (73.3 g) and the resulting solution was slowly cooled to 0°C. The resulting suspension was filtered and the product was dried in a drying oven at 60 °C under vacuum. 1H NMR (400MHz, CDCl3): δ 7.58 (s, 1H), 7.14-7.11 (m, 2H), 6.94-6.91 (m, 1H), 3.91 (s, 3H), 3.89 (s, 3H), 2.38 (s, 3H). Example 1d - alternative route to 4-Bromo-2-(3,4-dimethoxyphenyl)-6-methyl-pyridazin-3-one.

[0078] A suspension of 5-bromo-3-methyl-1H-pyridazin-6-one sodium salt (0.177 g, 0.78 mmol), previously prepared by deprotonation with NaH in THF and evaporation of the reaction mixture, and Pb(OAc)4 (0.437 g, 0.936 mmol) in veratrol (2.20 g, 15.6 mmol) was heated for 19 h at 100°C. The resulting brown reaction mixture was quenched by addition of saturated aq. The mixture was then extracted with DCM, the organic layer washed with water and dried over anhydrous MgSO4. Evaporation under reduced pressure gave a crude product as a solution in veratrol (2.45 g). Example 1e - alternative route to 4-Bromo-2-(3,4-dimethoxyphenyl)-6-methyl-pyridazin-3-one.

[0079] To a solution of 5-bromo-3-methyl-1H-pyridazin-6-one (1.10 g, 5.35 mmol) and veratrol (1.49 g, 10.7 mmol) in acetic acid ( 11 mL) Pb(OAc)4 (3.75 g, 6.77 mmol) was added. The resulting black suspension was stirred at 80°C for 16 h. The reaction mixture was then cooled to room temperature and evaporated almost to dryness under reduced pressure. The residue was diluted with DCM and poured into saturated aq. The resulting mixture was extracted with DCM (3x), the combined organic layer was washed with brine and dried over anhydrous MgSO4. Evaporation under reduced pressure gave the crude product (2.50 g). Example 1f - alternative route to 4-Bromo-2-(3,4-dimethoxyphenyl)-6-methyl-pyridazin-3-one.

[0080] To a solution of 5-bromo-3-methyl-1H-pyridazin-6-one (1.10 g, 5.35 mmol) and PhI(OAc)2 (2.13 g, 6.45 mmol) in trifluoroethanol (14 mL) veratrol (1.52 g, 10.8 mmol) was added and the resulting mixture was stirred at 70 °C for 24 h. The reaction mixture was cooled to room temperature and evaporated under reduced pressure. Example 1g - alternative route to 4-Bromo-2-(3,4-dimethoxyphenyl)-6-methyl-pyridazin-3-one.

[0081] To a suspension of 5-bromo-3-methyl-1H-pyridazin-6-one (0.100 g, 0.503 mmol) and CuCl (0.0051 g, 0.050 mmol) in DCM (1.5 mL) was added triethylamine (0.11 ml, 0.75 mmol) followed by (3,4-dimethoxyphenyl)-(2,4,6-trimethylphenyl)iodonium tetrafluoroborate (0.302 g, 0.528 mmol). The resulting suspension was stirred for 14 h at room temperature (complete conversion of starting material). The reaction mixture was diluted with DCM, washed with saturated aq NH4Cl, water and brine. The organic layer was dried over anhydrous MgSO4 and evaporated under reduced pressure to give the crude material (0.279 g). Example 1h - alternative route to 4-Bromo-2-(3,4-dimethoxyphenyl)-6-methyl-pyridazin-3-one - photochemical process. Variant 1 - solids-free process

[0082] 4-Bromo-2-chloro-6-methyl-pyridazin-3-one (5.0 g, 15.0 mmol, 94.5% purity), 1,2-dimethoxybenzene (5.7 g, 42 mmol), water (5.3 g, 30 mmol), Ruthenium dichloride(bipyridine).hydrate (26 mg, 0.03 mmol), acetonitrile (21 g, 511 mmol) and potassium acetate (5.8, 60 mmol) were charged into a reactor. The mixture was irradiated in the range of 420 - 460 nm (Blue Tuna Kessil Lamp light source) for 2 hours at room temperature with stirring. The aqueous phases were removed through extraction. The solvent and the residual amount of 1,2-dimethoxybenzene were removed by vacuum distillation. 1H NMR (400MHz, CDCl3): δ 7.58 (s, 1H), 7.14-7.11 (m, 2H), 6.94-6.91 (m, 1H), 3.91 (s, 3H), 3.89 (s, 3H), 2.38 (s, 3H). Variant 2 - suspension process

[0083] 4-Bromo-2-chloro-6-methyl-pyridazin-3-one (5.0 g, 15.0 mmol, 94.5% purity), 1,2-dimethoxybenzene (5.7 g, 42 mmol), Ruthenium dichloride (bipyridine).hydrate (26 mg, 0.03 mmol), acetonitrile (21 g, 511 mmol) and potassium acetate (5.8, 60 mmol) were charged into a reactor. The mixture was irradiated in the range of 420 - 460 nm (Blue Tuna Kessil Lamp light source) for 2 hours at room temperature with stirring. The aqueous phases were removed through extraction. The solvent and the residual amount of 1,2-dimethoxybenzene were removed by vacuum distillation. 1H NMR (400MHz, CDCl3): δ 7.58 (s, 1H), 7.14-7.11 (m, 2H), 6.94-6.91 (m, 1H), 3.91 (s, 3H), 3.89 (s, 3H), 2.38 (s, 3H). Example 1i: Alternative route to electrochemical 4-Bromo-2-(3,4-dimethoxyphenyl)-6-methyl-pyridazin-3-one.

[0084] A solution of 5-bromo-3-methyl-1H-pyridazin-6-one (2.89 g, 15.0 mmol, 98% purity), veratrol (50.2 g, 360 mmol, purity of 99%), potassium pivalate (2.21 g, 15.0 mmol, 95% purity) in methanol (104 g, 3.26 mol, >99% purity) was pumped (500 mL/min) through a electrolysis flow reactor (unsplit, electrode surface: 80 cm2, Ir/Ta MOX-anode, stainless steel-cathode, electrode-electrode distance = 1 mm) at a current density of 12.5 mA/cm2. The mixture was circulated through the installation consisting of a storage tank, pump and electrolysis reactor until full conversion of the starting material was achieved after 3 h.

[0085] The same general procedure as outlined in Example 1a above was used for the synthesis of compounds listed below. Example 2: 4-Bromo-2-(4-methoxyphenyl)-6-methyl-pyridazin-3-one

[0086] Crude 4-Bromo-2-(4-methoxyphenyl)-6-methyl-pyridazin-3-one (2.17 g) was obtained as a pale brown solid. Quantitative NMR analysis using trimethoxybenzene as an internal standard indicated 61% purity (88% chemical yield). The crude material was purified by silica gel chromatography (0-70% EtOAc in cyclohexane) to provide 4-bromo-2-(4-methoxyphenyl)-6-methyl-pyridazin-3-one (1.10 g, 75%, 98% purity) as a white crystalline solid. 1H NMR (400MHz, CDCl3): δ 7.57 (s, 1H), 7.54-7.47 (m, 2H), 7.09 (s, 1H), 7.00-6.94 (m, 2H), 3.85 (s, 3H), 2.39 (s, 3H). Example 3: 4-Bromo-6-methyl-2-[4-(trifluoromethyl)phenyl]pyridazin-3-one

[0087] Crude 4-Bromo-6-methyl-2-[4-(trifluoromethyl)phenyl]pyridazin-3-one (2.17 g) was obtained as a pale beige solid. Quantitative NMR analysis using trimethoxybenzene as an internal standard indicated 59% purity (79% chemical yield). The crude material was purified by silica gel chromatography (15-55% EtOAc in cyclohexane) to provide 4-bromo-6-methyl-2-[4-(trifluoromethyl)phenyl]pyridazin-3-one (1 .25 g, 77%, >99% purity) as a white crystalline solid. 1H NMR (400MHz, CDCl3): δ 7.80 (d, J= 8.4 Hz, 2H), 7.74 (d, J= 8.8 Hz, 2H), 7.61 (s, 1H), 2.41 (d, J= 1.5Hz, 3H). Example 4: 4-(5-Bromo-3-methyl-6-oxo-pyridazin-1-yl)benzonitrile

[0088] Crude 4-(5-Bromo-3-methyl-6-oxo-pyridazin-1-yl)benzonitrile (4.56 g) was obtained as a white solid. Quantitative NMR analysis using trimethoxybenzene as an internal standard indicated 33% purity (67% chemical yield). The crude material was purified by silica gel chromatography (20-100% EtOAc in cyclohexane) to provide 4-(5-bromo-3-methyl-6-oxo-pyridazin-1-yl)benzonitrile (1, 56 g, 60%, 86% purity) as a white crystalline solid. 1H NMR (400MHz, CDCl3): δ 7.88-7.74 (m, 4H), 7.61 (s, 1H), 2.42 (s, 3H). Example 5: 4-Bromo-6-methyl-2-(p-tolyl)pyridazin-3-one

[0089] Crude 4-Bromo-6-methyl-2-(p-tolyl)pyridazin-3-one (1.56 g) was obtained as a yellow solid. Quantitative NMR analysis using trimethoxybenzene as an internal standard indicated 78% purity (84% chemical yield). The crude material was purified by silica gel chromatography (0-50% EtOAc in cyclohexane) to provide 4-bromo-6-methyl-2-(p-tolyl)pyridazin-3-one (1.1 g , 74%, 97% purity) as a white crystalline solid. 1H NMR (400MHz, CDCl3): δ 7.58 (s, 1H), 7.46 (d, J= 8.4 Hz, 2H), 7.31-7. 22(m, 2H), 2.40 (s, 3H), 2.39 (s, 3H). Example 6: 4-Bromo-6-methyl-2-(m-tolyl)pyridazin-3-one

[0090] Crude 4-Bromo-6-methyl-2-(m-tolyl)pyridazin-3-one (1.96 g) was obtained as a yellow solid.

[0091] Quantitative analysis by NMR using trimethoxybenzene as an internal standard indicated purity of 67% (chemical yield of 90%). The crude material was purified by silica gel chromatography (20-50% EtOAc in cyclohexane) to provide 4-bromo-6-methyl-2-(m-tolyl)pyridazin-3-one (1.22 g , 81%, 97% purity) as a white crystalline solid. 1H NMR (400MHz, CDCl3): δ 7.59 (s, 1H), 7.41-7.32 (m, 3H), 7.25-7.18 (m, 1H), 2.41 (s, 3H), 2.39 (s, 3H). Example 7: 4-Bromo-6-methyl-2-(o-tolyl)pyridazin-3-one

[0092] Crude 4-Bromo-6-methyl-2-(o-tolyl)pyridazin-3-one (3.94 g) was obtained as a yellow oil.

[0093] Quantitative analysis by NMR using trimethoxybenzene as an internal standard indicated purity of 33% (chemical yield of 59%). The crude material was purified by silica gel chromatography (5-60% EtOAc in cyclohexane) to provide 4-bromo-6-methyl-2-(o-tolyl)pyridazin-3-one (1.34 g , 56%, purity 91%) as a yellow crystalline solid. 1H NMR (400MHz, CDCl3): δ 7.63 (s, 1H), 7.38-7.29 (m, 3H), 7.26-7.23 (m, 1H), 2.39 (s, 3H), 2.17 (s, 3H). Example 8: N-[4-(5-Bromo-3-methyl-6-oxo-pyridazin-1-yl)phenyl]acetamide

[0094] Crude N-[4-(5-Bromo-3-methyl-6-oxo-pyridazin-1-yl)phenyl]acetamide (1.52 g) was obtained as a yellow solid. Quantitative NMR analysis using trimethoxybenzene as an internal standard indicated 67% purity (61% chemical yield). The crude material was purified by silica gel chromatography (50-100% EtOAc in cyclohexane) to provide N-[4-(5-bromo-3-methyl-6-oxo-pyridazin-1-yl)phenyl ]acetamide (0.725 g, 40%, 91% purity) as a yellow crystalline solid. 1H NMR (400MHz, CDCl3): δ 7.60 (s, 1H), 7.57 (d, J= 8.8 Hz, 2H), 7.51 (d, J= 8.8 Hz, 2H), 2.40 (s, 3H), 2.19 (s, 3H). Example 9: 4-Bromo-2,6-dimethyl-pyridazin-3-one

[0095] Sodium hydride in paraffin oil (60%, 0.255 g, 6.66 mmol) was added to a solution of 5-bromo-3-methyl-1H-pyridazin-6-one (1.03 g, 5 .12 mmol) in DMF (7.2 mL) at 0 °C. After stirring for 20 min, iodomethane (6.66 mmol, 0.417 mL) was added via syringe at rt. The reaction medium heated noticeably and turned dark violet. After stirring for 1 h, the reaction was quenched by pouring into a mixture of aqueous NaHCO3 and Na2S2O3. The mixture was extracted with EtOAc (2x) and the combined organic layer washed with water and brine. Drying over anhydrous Na2SO4 and evaporation under reduced pressure gave 1.228 g of crude material as a black solid. Purification by silica gel chromatography (0-70% EtOAc in cyclohexane) gave 4-bromo-2,6-dimethyl-pyridazin-3-one (0.736 g, 70.4%, purity >99.5 %) as a white solid. 1H NMR (400MHz, CDCl3): δ 7.51 (s, 1H), 3.8 (s, 3H), 2.32 (s, 3H). Example 10: 4-Bromo-2-butyl-6-methyl-pyridazin-3-one

[0096] 4-Bromo-2-butyl-6-methyl-pyridazin-3-one was prepared by a procedure analogous to that described in example 9 from 1-iodobutane as a light yellow oil (1.387 g, 93.7 %, 99% purity) 1H NMR (400MHz, CDCl3): δ 7.48 (s, 1H), 4.19-4.12 (m, 2H), 2.32 (s, 3H), 1.84 -1.73 (m, 2H), 1.44-1.33 (m, 2H), 0.96 (t, J= 7.3, 3H). Example 11: (2Z)-2-[(3,4- Dimethoxyphenyl)hydrazono]propanal

[0097] A 5 L double jacketed reactor was charged with water (1.2 L) and cooled to 5 °C. Concentrated sulfuric acid (104 mL, 1.90 mol) was added slowly while maintaining the temperature below 25 °C. When the internal temperature had again reached 5 °C, 3,4-dimethoxyaniline (198.0 g, 1.27 mol) was added portion by portion. A solution of sodium nitrite (88.3 g, 1.27 mol) in water (0.25 L) was added to the dark violet suspension over 40 minutes while maintaining the internal temperature below 5 °C. The reaction mixture was stirred at 0 °C for 90 min followed by addition of 3-dimethylamino-2-methyl-2-propanal solution (137.2 g, 1.15 mol) and NaOAc (105.0 g, 1. 27 mol) in water (0.75 L) over 1 h while maintaining the internal temperature below 5 °C. After the addition was complete the reaction mixture was gradually allowed to reach 20°C over 2.5 h. The resulting black suspension was transferred to a 5 L Erlenmeyer flask and the reactor was washed with water (2 L) to remove most of the remaining precipitate. The solid product was separated by filtration, filter washed with water (1.5 L) and dried to constant weight at 50 °C and high vacuum for 40 h to give (2Z)-2-[(3,4-dimethoxyphenyl )hydrazono]propanal (199 g, 92% purity, 71% yield) as a red solid. This material was pure enough to be used in the next step. After standing for 16 h at room temperature, another portion of the product precipitated from the aqueous phase and was also filtered, washed and dried under vacuum to provide the second batch of (2Z)-2-[(3,4-dimethoxyphenyl)hydrazone ]propanal (43.7 g, 70% purity, 12% yield; 83% yield for both batches combined). 1H NMR (400MHz, CDCl3): δ 9.49 (s, 1H), 8.10 (sl, 1H), 7.00 (d, J = 2.6 Hz, 1H), 6.86 (d, J = 8.4 Hz, 1H), 6.70 (dd, J = 8.6, 2.4 Hz, 1H), 3.94 (s, 3H), 3.88 (s, 3H), 1.98 (s, 3H). Example 12: 4-Chloro-2-(3,4-dimethoxyphenyl)-6-methyl-pyridazin-3-one

[0098] (2Z)-2-[(3,4-dimethoxyphenyl)hydrazono]propanal (4.80 g, 96% purity, 20.7 mmol) was suspended in EtOH (62 mL). Triethyl 2-Chloro-2-phosphonoacetate (6.57 g, 24.9 mmol) was added at 0 °C followed by NaOEt (2.20 g, 31.1 mmol). The reaction was stirred at 0°C for 45 min before another portion of NaOEt (2.20 g, 31.1 mL) was added. After stirring for an additional 45 min, the reaction was quenched by addition of saturated aq. The resulting mixture was extracted by DCM (3x), the combined organic layers were washed with brine, dried over anhydrous Na2SO4 and concentrated under reduced pressure. The obtained residue was suspended in Et2O, stirred for 30 min and the precipitate was filtered off and dried to give 4-chloro-2-(3,4-dimethoxyphenyl)-6-methyl-pyridazin-3-one (4.91 g, 98% purity, 82% yield) as a light brown solid. 1H NMR (400MHz, CDCl3): δ 7.34 (s, 3H), 7.16-7.12 (m, 2H), 6.95-6.91 (m, 1H), 3.91 (s, 3H), 3.89 (s, 3H), 2.38 (s, 3H) Example 13: 2-[2-(3,4-Dimethoxyphenyl)-6-methyl-3-oxo-pyridazine-4-carbonyl] cyclohexane-1,3-dione

Method A

[0099] A pressure reactor (100 mL) was charged with 4-bromo-2-(3,4-dimethoxyphenyl)-6-methyl-pyridazin-3-one (3.00 g, 8.9 mmol), 1 Freshly purified ,3-cyclohexadione (1.31 g, 11.6 mmol), palladium acetate (0.00204 g, 0.00890 mmol) and Dpephos (0.00489 g, 0.0890 mmol). The system was purged with argon and then triethylamine (2.51 mL, 17.8 mmol) and acetonitrile (12.5 mL) were added. The reaction mixture was stirred under 10 bar CO at 60 °C for 4 h. After purging with Air and cooling to room temperature, the reaction mixture was concentrated under reduced pressure. The residue was taken up in DCM (100 mL) and washed with 1 M HCl (75 mL). The aq phase. was extracted with DCM (2x 100 mL). The combined organic layers were dried over Na2SO4, filtered and evaporated to give 2-[2-(3,4-dimethoxyphenyl)-6-methyl-3-oxo-pyridazine-4-carbonyl]cyclohexane-1,3-dione raw (3.858 g) of yellow-brown foam. Quantitative NMR analysis using trimethoxybenzene as a standard indicated purity of 81.7% (chemical yield of 92%). This material was suspended in EtOH (7.5 mL), heated to reflux and stirred for 30 min giving a clear solution. After cooling to room temperature, the resulting precipitate was separated by filtration, washed on a filter with a small amount of Et2O and dried under high vacuum to give 2-[2-(3,4-dimethoxyphenyl)-6-methyl-3- oxo-pyridazine-4-carbonyl]cyclohexane-1,3-dione (2.819 g, 99.2% purity, 82% isolated yield) as a bright yellow solid. 1H NMR (400MHz, CDCl3): δ 16.15 (s, 1H), 7.15-7.11 (m, 1H), 7.10-7.08 (m, 2H), 6.91 (d, J = 8.4 Hz, 1H), 3.90 (s, 3H), 3.89 (s, 3H), 2.72 (t, J = 6.2 Hz, 2H), 2.48-2, 43 (m, 2H), 2.41 (s, 3H), 2.04 (quin, J = 6.4 Hz, 2H).

Method B

[0100] A pressure flask was charged with 4-bromo-2-(3,4-dimethoxyphenyl)-6-methyl-pyridazin-3-one (0.200 g, 0.603 mmol), 1,3-cyclohexanedione (0.102 g, 0.905 mmol), Pd(OAc)2 (0.00276 g, 0.0121 mmol) and bis(1-adamantyl)-butyl-phosphane (0.00606 g, 0.0169 mmol). The system was purged with argon, then diisopropylethyl amine (0.21 mL, 1.21 mmol) and acetonitrile (2.5 mL) were added. The reaction mixture was stirred under 10 bar CO at 80 °C for 18 h. After cooling to room temperature and purging with argon, the reaction mixture was filtered through a celite pad. The filtrate was concentrated under reduced pressure, the residue was dissolved in dichloromethane and washed with saturated aq. The aqueous phase was extracted with dichloromethane (2x), the combined organic layers were dried over anhydrous Na2SO4 and concentrated under reduced pressure to give 2-[2-(3,4-dimethoxyphenyl)-6-methyl-3-oxo-pyridazine- 4-carbonyl]cyclohexane-1,3-dione (0.2684 g) as a yellow foam. Quantitative NMR analysis using trimethoxybenzene as an internal standard indicated 57.8% purity (67% chemical yield).

Method C

[0101] A pressure flask was charged with 4-chloro-2-(3,4-dimethoxyphenyl)-6-methyl-pyridazin-3-one (0.200 g, 0.698 mmol), 1,3-cyclohexanedione (0.103 g, 0.91 mmol), Pd(OAc)2 (0.0032 g, 0.014 mmol) and 1,4-bis(dicyclohexylphosphine)-butane (0.0064 g, 0.014 mmol). The system was purged with argon, then triethylamine (0.20 mL, 1.4 mmol) and acetonitrile (2.5 mL) were added. The reaction mixture was stirred under 10 bar CO at 80 °C for 18 h. After cooling to room temperature and purging with argon, the reaction mixture was filtered through a celite pad. The filtrate was concentrated under reduced pressure, the residue was dissolved in dichloromethane and washed with saturated aq. The aqueous phase was extracted with dichloromethane (2x), the combined organic layers were dried over anhydrous Na2SO4 and concentrated under reduced pressure to give 2-[2-(3,4-dimethoxyphenyl)-6-methyl-3-oxo-pyridazine- 4-carbonyl]cyclohexane-1,3-dione (0.295 g) as a brown foam. Quantitative NMR analysis using trimethoxybenzene as an internal standard indicated 49% purity (54% chemical yield).

[0102] The following compounds were prepared using Method A: Example 14: 2-[2-(4-Methoxyphenyl)-6-methyl-3-oxo-pyridazine-4-carbonyl]cyclohexane-1,3-dione

[0103] Crude 2-[2-(4-Methoxyphenyl)-6-methyl-3-oxo-pyridazine-4-carbonyl]cyclohexane-1,3-dione (0.541 g) was obtained as a yellow foam. Quantitative NMR analysis using trimethoxybenzene as an internal standard indicated 82% purity (95% chemical yield). 1H NMR (400MHz, CDCl3): δ 16.14 (sl, 1H), 7.54-7.46 (m, 2H), 7.09 (s, 1H), 6.99-6.93 (m, 2H), 3.83 (s, 3H), 2.73 (t, J= 6.2Hz, 2H), 2.47 (t, J= 5.9 Hz, 2H), 2.41 (s, 3H ), 2.10-1.99 (m, 2H). Example 15: 2-[6-Methyl-3-oxo-2-[4-(trifluoromethyl)phenyl]pyridazine-4-carbonyl]cyclohexane-1,3-dione

[0104] Crude 2-[6-Methyl-3-oxo-2-[4-(trifluoromethyl)phenyl]pyridazine-4-carbonyl]cyclohexane-1,3-dione (0.531 g) was obtained as a foam orange. Quantitative NMR analysis using trimethoxybenzene as an internal standard indicated 76% purity (86% chemical yield). 1H NMR (400MHz, CDCl3): δ 16.15 (s, 1H), 7.79 (d, J= 8.4 Hz, 2H), 7.71 (d, J= 8.8 Hz, 2H), 7.10 (s, 1H), 2.75 (t, J= 6.4 Hz, 2H), 2.48 (t, J= 6.6 Hz, 2H), 2.43 (s, 3H), 2.10-2.03 (m, 2H). Example 16: 4-[5-(2,6-Dioxocyclohexanecarbonyl)-3-methyl-6-oxo-pyridazin-1-yl]benzonitrile

[0105] Crude 4-[5-(2,6-Dioxocyclohexanecarbonyl)-3-methyl-6-oxo-pyridazin-1-yl]benzonitrile (0.482 g) was obtained as a yellow foam. Quantitative NMR analysis using trimethoxybenzene as an internal standard indicated 50% purity (58% chemical yield). 1H NMR (400MHz, CDCl3): δ 16.16 (s, 1H), 7.85-7.82 (m, 2H), 7.76-7.72 (m, 2H), 7.08 (s, 1H), 2.76 (t, J= 6.2 Hz, 2H), 2.49 (m, 2H), 2.43 (s, 3H), 2.11-2.03 (m, 2H). Example 17: 2-[6-Methyl-3-oxo-2-(p tolyl)pyridazine-4-carbonyl]cyclohexane-1,3-dione

[0106] Crude 2-[6-Methyl-3-oxo-2-(p-tolyl)pyridazine-4-carbonyl]cyclohexane-1,3-dione (0.531 g) was obtained as a green foam. Quantitative NMR analysis using trimethoxybenzene as an internal standard indicated 81% purity (92% chemical yield). 1H NMR (400MHz, CDCl3): δ 16.13 (s, 1H), 7.47-7.43 (m, 2H), 7.25 (d, J= 8.1 Hz, 2H), 7.10 (s, 1H), 2.73 (t, J= 6.4 Hz, 2H), 2.47 (t, J= 6.4 Hz, 2H), 2.41 (s, 3H), 2.38 (s, 3H), 2.09-2.01 (m, 2H). Example 18: 2-[6-Methyl-3-oxo-2-(m-tolyl)pyridazine-4-carbonyl]cyclohexane-1,3-dione

[0107] Crude 2-[6-Methyl-3-oxo-2-(m-tolyl)pyridazine-4-carbonyl]cyclohexane-1,3-dione (0.528 g) was obtained as a yellow foam. Quantitative NMR analysis using trimethoxybenzene as an internal standard indicated 83% purity (94% chemical yield). 1H NMR (400MHz, CDCl3): δ 16.14 (s, 1H), 7.39-7.31 (m, 2H), 7.18 (d, J= 6.6 Hz, 2H), 7.10 (s, 1H), 2.73 (t, J= 6.4 Hz, 2H), 2.48 (t, J= 6.4 Hz, 2H), 2.42 (s, 3H), 2.40 (s, 3H), 2.10-2.01 (m, 2H). Example 19: 2-[6-Methyl-3-oxo-2-(o-tolyl)pyridazine-4-carbonyl]cyclohexane-1,3-dione

[0108] Crude 2-[6-Methyl-3-oxo-2-(o-tolyl)pyridazine-4-carbonyl]cyclohexane-1,3-dione (0.525 g) was obtained as a yellow foam. Quantitative NMR analysis using trimethoxybenzene as an internal standard indicated 80% purity (95% chemical yield). 1H NMR (400MHz, CDCl3): δ 16.03 (sl, 1H), 7.34- 7.24 (m, 4H), 7.17 (s, 1H), 2.71 (t, J= 6, 2 Hz, 2H), 2.46 (t, J= 6.2 Hz, 2H), 2.41 (s, 3H), 2.23 (s, 3H), 2.08-1.99 (m, 2H). Example 20: N-[4-[5-(2,6-Dioxocyclohexanecarbonyl)-3-methyl-6-oxo-pyridazin-1-yl]phenyl]acetamide

[0109] Crude N-[4-[5-(2,6-Dioxocyclohexanecarbonyl)-3-methyl-6-oxo-pyridazin-1-yl]phenyl]acetamide (0.545 g) was obtained as a yellow foam . Quantitative NMR analysis using trimethoxybenzene as an internal standard indicated 65% purity (83% chemical yield). 1H NMR (400MHz, CDCl3): δ 16.19 (sl, 1H), 7.59- 7.47 (m, 4H), 7.09 (s, 1H), 2.74 (t, J= 6, 2 Hz, 2H), 2.47 (t, J= 6.6 Hz, 2H), 2.41 (s, 3H), 2.14 (s, 3H), 2.09-2.01 (m, 2H). Example 21: 2-(2,6-Dimethyl-3-oxo-pyridazine-4-carbonyl)cyclohexane-1,3-dione

[0110] Crude 2-(2,6-Dimethyl-3-oxo-pyridazine-4-carbonyl)cyclohexane-1,3-dione (0.586 g) was obtained as a yellow gum. Quantitative NMR analysis using trimethoxybenzene as an internal standard indicated 78% purity (89% chemical yield). 1H NMR (400MHz, CDCl3): δ 16.16 (s, 1H), 7.04 (s, 1H), 3.74 (s, 1H), 2.75 (t, J= 6.2 Hz, 2H ), 2.49 (t, J= 6.6 Hz, 2H), 2.35 (s, 3H), 2.11-2.03 (m, 2H). Example 22: 2-(2-Butyl-6-methyl-3-oxo-pyridazine-4-carbonyl)cyclohexane-1,3-dione

[0111] Crude 2-(2-Butyl-6-methyl-3-oxo-pyridazine-4-carbonyl)cyclohexane-1,3-dione (0.559 g) was obtained as a yellow gum. Quantitative NMR analysis using trimethoxybenzene as an internal standard indicated 73% purity (83% chemical yield). 1H NMR (400MHz, CDCl3): δ 16.16 (s, 1H), 7.01 (s, 1H), 4.10 (t, J= 7.3, 2H), 2.73 (t, J= 6.2, 2H), 2.48 (t, J= 6.6 Hz, 2H), 2.35 (s, 3H), 2.11-2.02 (m, 2H), 1.81-1 .71 (m, 2H), 1.44-1.32 (m, 2H), 0.94 (t, J= 7.3 Hz, 3H). Example 23: 2-(3-Methyl-6-oxo-1H-pyridazine-5-carbonyl)cyclohexane-1,3-dione

[0112] Crude 2-(3-Methyl-6-oxo-1H-pyridazine-5-carbonyl)cyclohexane-1,3-dione (1.480 g) was obtained as a beige foam. Quantitative NMR analysis using trimethoxybenzene as an internal standard indicated 65% purity (79% chemical yield). 1H NMR (400MHz, CDCl3): δ 16.10 (s l, 1H), 11.44 (s l, 1H), 7.09 (s, 1H), 2.80-2.69 (m, 2H), 2 .55-2.45 (m, 2H), 2.35 (s, 3H), 2.12-2.03 (m, 2H).

Claims (15)

1. Process for producing a compound of Formula (I): characterized by the fact that R1 is selected from the group consisting of hydrogen, C1-C6 alkyl, C1-C6 haloalkyl, C1-C3alkoxyC1-C3alkyl-, C1-C3alkoxyC2-C3alkoxyC1-C3alkyl-, aryl and a heteroaryl with 5 or 6 members, wherein the heteroaryl contains one to three heteroatoms each independently selected from the group consisting of oxygen, nitrogen and sulfur, and wherein the aryl and heteroaryl component may be optionally substituted; R2 is C1-C6 alkyl or C3-C6 cycloalkyl; A1 is selected from the group consisting of O, C(O) and (CR7R8); and R4, R6, R7 and R8 are each independently selected from the group consisting of hydrogen and C1-C4 alkyl; R3 and R5 are each independently selected from the group consisting of hydrogen and C1-C4 alkyl or together form a C1-C3 alkylene chain; comprising the reaction process of a compound of Formula (II) where X is a halogen; with a compound of Formula (III) wherein A1 and R3, R4, R5 and R6 are as defined with respect to Formula (I) above; in a reaction medium comprising: (i) a palladium catalyst; (ii) a suitable phosphine ligand or phosphine ligand salt; (iii) a suitable base: and (iv) carbon monoxide; to give a compound of Formula (I). 2. Process according to claim 1, characterized by the fact that R1 is an optionally substituted heteroaryl. 3. Process according to claim 1, characterized by the fact that R1 is an optionally substituted phenyl. 4. Process according to claim 3, characterized by the fact that R1 is phenyl optionally substituted by one or more substituents selected from the group consisting of halo, C1-C4 alkyl, C1-C4 haloalkyl, C1-C3 alkoxy, cyano and nitro. 5. Process according to claim 4, characterized by the fact that R1 is 3,4-dimethoxyphenyl. 6. Process according to any one of claims 1, 2, 3, 4 and 5, characterized by the fact that R2 is methyl. 7. Process according to any one of claims 1, 2, 3, 4, 5 and 6, characterized in that X is selected from the group consisting of Br, Cl and I. 8. Process according to any one of claims 1, 2, 3, 4, 5, 6 and 7, characterized by the fact that X is Br. 9. Process according to any one of claims 1, 2, 3, 4, 5, 6, 7 and 8, characterized by the fact that A1 is CR7R8 and R3, R4, R5, R6, R7 and R8 are hydrogen. 10. Process according to any one of claims 1, 2, 3, 4, 5, 6, 7, 8 and 9, characterized in that the reaction medium additionally comprises (v) a solvent. 11. Process according to claim 10, characterized by the fact that the solvent is acetonitrile. 12. Compound characterized by the fact that it is of Formula (IIa1a) 13. Process for producing a compound of Formula (IIa1a) characterized by the fact that it comprises the reaction of a compound of Formula (X) wherein R9 is selected from the group consisting of Cl, Br and I; with a compound of Formula (XI) 14. Process according to claim 13, characterized by the fact that Compound (X) and Compound (XI) are reacted using a photochemical catalyzed procedure. 15. Compound of Formula (X) characterized by the fact that R9 is selected from the group consisting of Cl, Br and I.