Process of preparing a triazine compound and its novel polymorph

Abstract

The present invention relates to a process of preparing a triazine compound of formula I and its novel polymorphic forms. The present invention further relates to the composition comprising the novel polymorphic form of compound of formula I.

Description

[0001] “Process of preparing a Triazine compound and its novel polymorph”

[0002] Field of invention

[0003] The present invention relates to a process of preparing a triazine compound of formula I and its novel polymorphic forms. The present invention further relates to the composition comprising the novel polymorphic form of compound of formula I.

[0004] Background of the invention

[0005] Triazine compounds are a class of compounds suitable for being used as herbicides. Triazine compounds such as atrazine, ametryne, indaziflam ortriaziflam are among the compounds that are used as herbicides.

[0006] N-[(lR,2S)-2,6-dimethyindan-l-yl]-6-(l-fluoroethyl)-l,3,5-triazine-2,4-diamine is an herbicide belonging to the class of cellulose synthesis inhibitor. It is used as a pre-emergence herbicide for the control of annual grasses and broad-leaved weeds in citrus, grapes, fruit trees, Christmas tree farms, lawns and sports fields N- [( 1 R,2S)-2,6-dimethyindan- 1 -yl] -6-( 1 -fluoroethyl)- 1 ,3 ,5 -triazine-2,4-diamine is a diastereoisomeric mixture of the two fluoroethyl diastereoisomers of N-(2,6- dimethylindan-l-yl)-6-(l-fluoroethyl)-l,3,5-triazine-2,4-diamine in which the indane moiety has 1R,2S configuration.. The two diastereoisomers have very similar biological activity. Commercially, N-[(lR,2S)-2,6-dimethyindan-l-yl]-6- (l-fluoroethyl)-l,3,5-triazine-2,4-diamine is a 95:5 mixture of the (1R,2S, fluoroethyl-R) and (lR,2S,fluoroethyl-S) diastereoisomers. It contains a N- [(lR,2S)-2,6-dimethyindan-l-yl]-6-[(lR)-l-fluoroethyl]-l,3,5-triazine-2,4- diamine and a N-[(lR,2S)-2,6-dimethyindan-l-yl]-6-[(lS)-l-fluoroethyl]-l,3,5- triazine-2,4-diamine in the ratio of 95:5.

[0007] There are several prior art documents which disclose the preparation of N-[( 1R,2S)- 2,6-dimethyindan- 1 -yl] -6-( 1 -fluoroethyl)- 1 ,3 ,5 -triazine-2,4-diamine and its intermediates. EP 1 592 674, EP 2 231 679 and EP3 347 342 disclose different methods for preparing N-[( 1 R, 2S)-2,6-dimethyindan- 1 -yl] -6-( 1 -fluoroethyl)- 1 ,3 ,5 -triazine- 2,4-diamine. However, the processes disclosed in each of the prior art suffers some drawbacks such as low yield in the preparation of biguanidine intermediate or an acid addition salt thereof, or reaction at very high temperatures.

[0008] Some of the prior art processes generates large amounts of waste requiring costly and complex disposal processes.

[0009] Some of the processes disclosed in the prior art, requires a combination of several solvents for each step, thereby posing an operational challenge while trying to recycle and isolate each of the solvents.

[0010] Moreover, none of the prior arts discloses a process for preparing amorphous polymorph of N- [( 1 R,2S)-2,6-dimethyindan- 1 -yl] -6-( 1 -fluoroethyl)- 1 ,3 ,5 -triazine- 2,4-diamine.

[0011] Therefore, there is a need to provide a process for the preparation of N-[(1R, 2S)- 2, 6-dimethyindan-l-yl]-6-(l-fluoroethyl)-l,3,5-triazine-2,4-diamine that mitigates the aforementioned drawbacks or at least provides a useful and economical alternative. Further, there is the need to provide a novel form of N-[(1R, 2S)-2, 6- dimethyindan- 1 -yl] -6-( 1 -fluoroethyl)- 1 ,3 ,5 -triazine-2,4-diamine, which has improved properties.

[0012] Summary of the invention

[0013] Thus, we have surprisingly found that the present invention provides an alternative to the existing methods for the preparation ofN-[(lR, 2S)-2, 6-dimethyindan-l-yl]- 6- [(1 -fluoroethyl)- 1,3, 5 -triazine-2,4-diamine, which solves the drawbacks of low yield, waste to be handled, reaction at high temperature or operationally complicated isolation. In an aspect, the present invention relates to a process for preparing a compound of formula I,

[0014] Compound of formula I comprising at least the steps of: a) reacting compound of formula II,

[0015] Compound of formula II where X is an organic acid salt or a mineral acid salt, with 1 -cyanoguanidine in the presence of a solvent SI, to produce compound of formula III which is optionally isolated,

[0016] Compound of formula III where X an organic acid salt or a mineral acid salt, b) reacting the compound of formula III obtained in step a) with compound of formula IV,

[0017] Compound of formula IV in the presence of, i. solvent S2, ii. at least one base B, to produce compound of formula I and, c) purifying the compound of formula I obtained in step b).

[0018] In the second aspect, the present invention relates to the purification process wherein the purification step comprises, i. suspending compound of formula I obtained in step b) in solvent S3 and adjusting the pH of the solution in the range of 1-2 and adding water to obtain a clear solution, ii. separating the aqueous layer, iii. cooling the aqueous layer to 5°C -10°C and adjusting the pH of the solution in the range of 7-8, and iv. isolating the resulting precipitate to give Form G of compound of formula I.

[0019] In the third aspect, the present invention relates to an amorphous form of compound of formula I, which is form G.

[0020] In the fourth aspect, the present invention relates to the purification process wherein the purification step comprises, i. suspending compound of formula I obtained in step b) in solvent S4 and heating it at 70°C -80°C for a time period of 45-90 min, ii. distilling a part of the solvent under reduced pressure, iii. cooling the solution to 25°C -30°C, and iv. isolating the resulting precipitate to give Form H of compound of formula I.

[0021] In the fifth aspect, the present invention relates to a polymorphic form of compound of formula I, which is form H.

[0022] In the sixth aspect, the present invention relates to a composition comprising, i. compound of formula I of form G or form H, or ii. its mixture with a second active compound, and iii. one or more inert additives. In the seventh aspect, the present invention relates to a method of controlling undesired vegetation, by applying the composition comprising compound of formula I of form G or form H to plants, their environment and / or seeds.

[0023] Brief Description of the Drawings

[0024] FIG. 1 is an X-ray powder diffractogram (XRD) of the amorphous form of compound of formula I of the present invention from a sample obtained from example 4 and recorded using Cu-Ka radiation at 25 °C.

[0025] FIG. 2 is an X-ray powder diffractogram (XRD) of crystalline form H of compound of formula I of the present invention from a sample obtained from example 1 and recorded using Cu-Ka radiation at 25°C.

[0026] Detailed description of the invention

[0027] In describing the embodiment of the invention, specific terminology is chosen for the sake of clarity. However, it is not intended that the invention be limited to the specific terms so selected and it is to be understood that such specific terms include all technical equivalents that operate in a similar manner to accomplish a similar purpose. It is understood that any numerical range recited herein is intended to include all subranges subsumed. In addition, unless denoted otherwise percentage of components in a composition are presented as weight percent.

[0028] Embodiments, of the present disclosure, will now be described herein. Embodiments are provided so as to thoroughly and fully convey the scope of the present disclosure to the person skilled in the art. Numerous details are set forth, relating to specific components, and methods, to provide a complete understanding of embodiments of the present disclosure. It will be apparent to the person skilled in the art that the details provided in the embodiments should not be construed to limit the scope of the present disclosure. In some embodiments, well-known processes, well-known apparatus structures, and well-known techniques are not described in detail. The terminology used, in the present disclosure, is only for the purpose of explaining a particular embodiment and such terminology shall not be considered to limit the scope of the present disclosure. As used in the present disclosure, the forms "a,” "an," and "the" may be intended to include the plural forms as well, unless the context clearly suggests otherwise.

[0029] The terms "comprises," "comprising," “including,” and “having,” are open ended transitional phrases and therefore specify the presence of stated features, integers, steps, operations, elements, modules, units and / or components, but do not forbid the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. The particular order of steps disclosed in the method and process of the present disclosure is not to be construed as necessarily requiring their performance as described or illustrated. It is also to be understood that additional or alternative steps may be employed.

[0030] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed elements.

[0031] The term “chiral purity” (or optical purity) is defined as the fractional excess of one enantiomer over the other.

[0032] In an embodiment, the present invention relates to the process for preparing a compound of formula I,

[0033] Compound of formula I comprising, at least the steps of: a) reacting compound of formula II,

[0034] Compound of formula II where X is an organic acid salt or a mineral acid salt, with 2-cyanoguanidine in the presence of a solvent SI, to produce compound of formula III or its acid addition salt which is optionally isolated,

[0035] Compound of formula III where X is an organic acid salt or a mineral acid salt, b) reacting the compound of formula III obtained in step a) with compound of formula IV,

[0036] Compound of formula IV in the presence of, i. solvent S2, ii. at least one base B, to produce compound of formula I and, c) purifying the compound of formula I obtained in step b).

[0037] The process of preparation of compound of formula I is detailed below:

[0038] Step a)

[0039] In an embodiment, the process of step a) comprises reacting compound of formula

[0040] II,

[0041] Compound of formula II where X is an organic acid salt or a mineral acid salt, with 2-cyanoguanidine in the presence of a solvent SI, to produce compound of formula III or an acid addition salt thereof, which is optionally isolated,

[0042] Compound of formula III where X is an organic acid salt or a mineral acid salt.

[0043] In an embodiment, solvent SI of step a), is selected from N,N-dimethylformamide, dimethylacetamide, N- methylpyrrolidone, dimethylsulfoxide, acetonitrile, benzonitrile, nitromethane, nitrobenzene, y-butyrolactone, sulfolane, nitromethane, tetramethyl urea, propylene carbonate, hexamethylphosphoramide, butanone, methyl isobutyl ketone, acetone, pyridine N,N- dimethylpropyleneurea , monochlorobenzene, bromobenzene, o-dichlorobenzene, m-dichlorobenzene, p- dichlorobenzene, anisole, toluene, benzene, ethylbenzene, xylenes, cumene, cymenes, mesitylene, biphenyl, decalin, n-butyl acetate, hexyl acetate, white mineral oil, tetrachloroethylene or dibutylether , tetrahydrofuran, ,2 methyltetrahydrofuran or combinations thereof.

[0044] In an embodiment, solvent S 1 of step a) is selected from N- methyl Pyrrolidone, N, N-diemthyl formamide, dimethyl acetamide, acetonitrile, formamide, monochlorobenzene, dichlorobenzene, dibutyl ether, tetrahydrofuran, 2 methyltetrahydrofuran or combinations thereof.

[0045] In an embodiment, X is an organic acid salt which is selected from salts of acetic acid, citric acid, formic acid, lactic acid, or oxalic acid.

[0046] In an embodiment, X is a mineral acid salt which is selected from hydrochloric acid, hydro bromic acid, sulphuric acid or nitric acid. Preferably, X is selected from Hydrochloric acid or Hydrobromic acid.

[0047] In an embodiment, the reaction of step a) is carried out at a temperature in the range of 80°C -140°C, preferably in the range of 90°C -I30°C, preferably in the range of 100°C -I30°C.

[0048] In an embodiment, the reaction of step a) is carried out at a temperature in the range of 110°C -130°C, preferably in the range of 120°C -I30°C.

[0049] In another embodiment, the reaction of step a) is carried out for a time period in the range of 6 hr to 12 hr, preferably 8 to 12 hr.

[0050] In a further embodiment, in the reaction of step a) the molar ratio of compound of formula II to 2-cyanoguanidine is in the range of 1: 3 more preferably 1: 1.5.

[0051] Step b)

[0052] In an embodiment, the process of step b) comprises reacting the compound of formula III or an acid addition salt thereof obtained in step a) with compound of formula IV

[0053] Compound of formula IV in the presence of, i. solvent S2, ii. at least one base B, to produce compound of formula I.

[0054] In an embodiment, solvent S2 of step b), is selected from methanol, ethanol, propanol, N,N-dimethylformamide, dimethylacetamide, N- methylpyrrolidone, dimethylsulfoxide, acetonitrile, benzonitrile, nitromethane, nitrobenzene, y- butyrolactone, sulfolane, nitromethane, tetramethyl urea, propylene carbonate, hexamethylphosphoramide, butanone, methyl isobutyl ketone, acetone, pyridine N,N- dimethylpropyleneurea, monochlorobenzene, bromobenzene, o- dichlorobenzene, m-dichlorobenzene, p-dichlorobenzene, anisole, toluene, benzene, ethylbenzene, xylenes, cumene, cymenes, mesitylene, biphenyl, decalin, n-butyl acetate, hexyl acetate, white mineral oil, tetrachloroethylene , dibutylether, tetrahydrofuran, 2 methyl- tetrahydrofuran or combination thereof.

[0055] In an embodiment, solvent S2 of step b) is selected from N- methyl Pyrrolidone, N, N-diemthyl formamide, dimethyl acetamide, acetonitrile, formamide, monochlorobenzene, dichlorobenzene, methanol, ethanol, propanol, dibutyl ether, tetrahydrofuran, 2 methyl- tetrahydrofuran or combination thereof.

[0056] In an embodiment, the base B is selected from metal alkoxide, metal hydroxides, or metal carbonates.

[0057] In an embodiment, the base B is selected from sodium methoxide, sodium ethoxide, potassium tert butoxide, sodium tert butoxide, sodium hydroxide, potassium hydroxide, lithium hydroxide, cesium hydroxide, sodium carbonate, potassium carbonate, cesium carbonate, or lithium carbonate.

[0058] Preferably the base B is selected from sodium methoxide, sodium tert butoxide, sodium hydroxide, potassium hydroxide.

[0059] In an embodiment, the reaction of step b) is carried out at a temperature in the range of 20°C - 90°C, preferably in the range of 20°C - 60°C, preferably in the range of 20°C - 40°C.

[0060] In another embodiment, the reaction of step b) is carried out for a time period in the range of 8 hr to 12 hr, preferably 8 hr to 10 hr. In a further embodiment, in the reaction of step b) the molar ratio of compound of formula III or an acid addition salt thereof to compound of formula IV is in the range of 1: 1.5 moles.

[0061] The process for the preparation of compound of formula I may be carried out as one-pot synthesis without isolation of compound of formula III or its acid addition salt, or it may be performed in 2 separate steps with isolation of compound of formula III or an acid addition salt thereof.

[0062] In an embodiment, compound of formula III or an acid addition salt thereof may be isolated after step a) by any conventional method known by the person skilled in the art, including but not limited to fdtration, washing the reaction product with a solvent or mixture of solvents in order to dissolve the impurities of compound of formula III or an acid addition salt thereof.

[0063] In other embodiment, compound of formula III or an acid addition salt thereof is not isolated, then, the preparation of compound of formula I is carried out in a one- pot synthesis, and the solvent from step a) is removed before the reaction of step b) of the process of the invention. The solvent may be removed by any conventional method known by the person skilled in the art, including but not limited to distillation, or distillation under vacuum.

[0064] Step c)

[0065] In an embodiment, the process of step c), the purification comprises, i. suspending compound of formula I obtained in step b) in solvent S3 and adjusting the pH of the solution in the range of 1-2 and adding water to obtain a clear solution, ii. separating the aqueous layer, iii. cooling the aqueous layer to 5°C -10°C and adjusting the pH of the solution in the range of 7-8, and iv. isolating the resulting precipitate to give Form G of compound of formula I.

[0066] In an embodiment, solvent S3 of step c) is selected from ethyl acetate, isopropyl acetate, butyl acetate, toluene, ether, isopropyl ether, dibutyl ether cyclopentyl methyl ether, toluene, methylene dichloride or methyl cyclohexane.

[0067] In an embodiment, the pH of the solution is adjusted in the range of 1-2, with the help of acid selected from hydrochloric acid, hydrobromic acid, nitric acid, formic acid, sulfuric acid, methane sulfonic acid, trifluoromethane sulfonic acid, trifluoro acetic acid.

[0068] In an embodiment, the pH of the solution is adjusted in the range of 7-8 with the help of base selected from metal hydroxides or metal carbonates.

[0069] In an embodiment, the base is selected from hydroxides like sodium hydroxide, potassium hydroxide, lithium hydroxide, cesium hydroxide or carbonates like sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, cesium carbonate. Preferably, the base is an aqueous base.

[0070] In an embodiment, the present invention relates to a polymorphic form G of compound of formula I, which is amorphous in nature.

[0071] The Form G of compound of formula I may exhibit an X-ray powder diffractogram (XRD) recorded using Cu-Ka radiation at 25°C as indicated in figure 1.

[0072] The Form G of compound of formula I may exhibit an infrared (IR) spectrum with characteristic functional peaks at wavenumbers (±2cm-1) at 823.1, 874.0, 957.3, 1054.7, 1123.6, 1186.4,1250.6,1528.2,1576.7 ,1637.5, 2898.0 ,2949.7 ,3222.3 ,3319.5 ,3432.8 cm’1. The Form G of compound of formula I exhibits an X-ray powder diffractogram (XRD) recorded using Cu-Ka radiation at 25 °C as indicated in figure 1, and it may exhibit an infrared (IR) spectrum with characteristic functional peaks at wavenumbers (±2cm’1) at 823.1, 874.0, 957.3, 1054.7, 1123.6, 1186.4, 1250.6, 1528.2, 1576.7 ,1637.5, 2898.0 ,2949.7 ,3222.3 ,3319.5 ,3432.8 cm’1.

[0073] The Form G of compound of formula I may exhibit a melting point of from 180 °C to 182 °C.

[0074] In an embodiment, the form G of compound of formula I, exhibits chiral purity >97% with isomeric ratio of N-[(lR,2S)-2,6-dimethyindan-l-yl]-6-[(lR)-l- fhioroethyl]-l,3,5-triazine-2,4-diamine and a N-[(lR,2S)-2,6-dimethyindan-l-yl]- 6-[(lS)-l-fhioroethyl]-l,3,5-triazine-2,4-diamine as 97: 3.

[0075] In an embodiment, the form G of compound of formula I, exhibits chiral purity >95% with isomeric ratio of N-[(lR,2S)-2,6-dimethyindan-l-yl]-6-[(lR)-l- fhioroethyl]-l,3,5-triazine-2,4-diamine and a N-[(lR,2S)-2,6-dimethyindan-l-yl]- 6-[(lS)-l-fhioroethyl]-l,3,5-triazine-2,4-diamine as 95: 5.

[0076] In an embodiment, the Form G of compound of formula I has one or more analytical parameter selected from the group consisting of, a XRD pattern as indicated in figure 1, a melting point in the range of from 180 °C to 182 °C, an infrared (IR) spectrum with characteristic functional peaks at wavenumbers (±2cm’1) 823.1, 874.0, 957.3, 1054.7, 1123.6, 1186.4,1250.6,1528.2,1576.7 ,1637.5, 2898.0, 2949.7 ,3222.3 , 3319.5 ,3432.8 cm^or chiral purity >97% with isomeric ratio of N-[(lR,2S)-2,6- dimethyindan- 1 -yl] -6-[( 1 R)- 1 -fluoroethyl] - 1 ,3,5 -triazine-2,4- diamine and a N-[(lR,2S)-2,6-dimethyindan-l-yl]-6-[(lS)-l- fhioroethyl]-l,3,5-triazine-2,4-diamine as 97: 3. In an embodiment, the Form G of compound of formula I has one or more analytical parameter selected from the group consisting of, a XRD pattern as indicated in figure 1, a melting point in the range of from 180 °C to 182 °C, an infrared (IR) spectrum with characteristic functional peaks at wavenumbers (±2cm’1) 823.1, 874.0, 957.3, 1054.7, 1123.6, 1186.4,1250.6,1528.2,1576.7 ,1637.5, 2898.0, 2949.7 ,3222.3 , 3319.5 ,3432.8 cm^or chiral purity >95% with isomeric ratio of N-[(lR,2S)-2,6- dimethyindan- 1 -yl] -6-[( 1 R)- 1 -fluoroethyl] - 1 ,3,5 -triazine-2,4- diamine and a N-[(lR,2S)-2,6-dimethyindan-l-yl]-6-[(lS)-l- fluoroethyl]-l,3,5-triazine-2,4-diamine as 95: 5.

[0077] In an embodiment, the process of step c), the purification comprises, i. suspending compound of formula I obtained in step b) in solvent S4 and heating it at 70°C -80°C for a time period of 45-90 min ii. distilling a part of the solvent under reduced pressure, iii. cooling the solution to 25°C -30°C, and iv. isolating the resulting precipitate to give Form H of compound of formula I.

[0078] In an embodiment, the solvent S4 is selected from water, methanol, ethanol, propanol, butanol, isopropanol isobutanol, acetonitrile, or mixture of solvents. Preferably, solvent S4 is selected from methanol, ethanol, isopropanol, or propanol. In an embodiment, the present invention relates to a polymorphic form H of compound of formula I, which is crystalline in nature.

[0079] The Form H of compound of formula I may exhibit an X-ray powder diffractogram (XRD) recorded using Cu-Ka radiation at 25°C as indicated in figure 2.

[0080] The Form H of compound of formula I may exhibit an infrared (IR) spectrum with characteristic functional peaks at wavenumbers (±2cm-l) at 822.4 ,873.8 ,957.2, 1054.1, 1123.3, 1185.6, 1250.5, 1527.4, 1576.3, 1638.8, 2898.5, 2950.3, 3224.8, 3319.9, 3433.4 cm’1.

[0081] The Form H of compound of formula I exhibits an X-ray powder diffractogram (XRD) recorded using Cu-Ka radiation at 25 °C as indicated in figure 4, and it may exhibit an infrared (IR) spectrum with characteristic functional peaks at wavenumbers (±2cm-l) 822.4 ,873.8 ,957.2, 1054.1, 1123.3, 1185.6,1250.5, 1527.4, 1576.3, 1638.8, 2898.5, 2950.3, 3224.8, 3319.9, 3433.4 cm

[0082] The Form H of compound of formula I may exhibit a melting point of from 181.4 °C to 183.4 °C.

[0083] In an embodiment, the form H of compound of formula I, exhibits chiral purity >97% with isomeric ratio of N-[(lR,2S)-2,6-dimethyindan-l-yl]-6-[(lR)-l- fhioroethyl]-l,3,5-triazine-2,4-diamine and a N-[(lR,2S)-2,6-dimethyindan-l-yl]- 6-[(lS)-l-fhioroethyl]-l,3,5-triazine-2,4-diamine as 97: 3.

[0084] In an embodiment, the form H of compound of formula I, exhibits chiral purity >95% with isomeric ratio of N-[(lR,2S)-2,6-dimethyindan-l-yl]-6-[(lR)-l- fhioroethyl]-l,3,5-triazine-2,4-diamine and a N-[(lR,2S)-2,6-dimethyindan-l-yl]- 6-[(lS)-l-fhioroethyl]-l,3,5-triazine-2,4-diamine as 95: 5.

[0085] In an embodiment, the Form H of compound of formula I has one or more analytical parameter selected from the group consisting of a XRD pattern as indicated in figure 2, a melting point in the range of from 182°C -184°C, an infrared (IR) spectrum with characteristic functional peaks at wavenumbers (±2cm’1) 822.4 ,873.8 ,957.2, 1054.1, 1123.3, 1185.6,1250.5, 1527.4, 1576.3, 1638.8, 2898.5, 2950.3, 3224.8, 3319.9, 3433.4 cm’1, or chiral purity >97% with isomeric ratio of N-[(lR,2S)-2,6- dimethyindan- 1 -yl] -6-[( 1 R)- 1 -fluoroethyl] - 1 ,3,5 -triazine-2,4- diamine and a N-[(lR,2S)-2,6-dimethyindan-l-yl]-6-[(lS)-l- fluoroethyl]-l,3,5-triazine-2,4-diamine as 97: 3.

[0086] In an embodiment, the Form H of compound of formula I has one or more analytical parameter selected from the group consisting of a XRD pattern as indicated in figure 2, a melting point in the range of from 182°C -184°C, an infrared (IR) spectrum with characteristic functional peaks at wavenumbers (±2cm’1) 822.4 ,873.8 ,957.2, 1054.1, 1123.3, 1185.6,1250.5, 1527.4, 1576.3, 1638.8, 2898.5, 2950.3, 3224.8, 3319.9, 3433.4 cm’1, or chiral purity >95% with isomeric ratio of N-[(lR,2S)-2,6- dimethyindan- 1 -yl] -6-[( 1 R)- 1 -fluoroethyl] - 1 ,3,5 -triazine-2,4- diamine and a N-[(lR,2S)-2,6-dimethyindan-l-yl]-6-[(lS)-l- fluoroethyl]-l,3,5-triazine-2,4-diamine as 95: 5.

[0087] Solvent recrystallization for preparing Form H

[0088] In an embodiment, Form H of compound of formula I can be obtained by solvent recrystallization. In an embodiment, the crude compound of formula I is heated and dissolved in a solvent at a temperature in the range of 50°C-80°C for a period of about 15 min-60min. After clear solution, the solvent is optionally partially distilled and allowed to crystallize by cooling at about 5°C-20°C. In an embodiment, the solvent is selected from ethyl acetate, butyl acetate or isopropyl acetate. Preferably, the solvent is ethyl acetate.

[0089] Interconversion of Form G and Form H

[0090] In an embodiment, the Form G can be converted to form H. Alternatively form H can be converted to Form G. In an embodiment, Form H can be converted to Form G in the presence of fluorinated alcohols such as 2, 2, 2-trifluoroethanol, 2,2-difluoroethanol, 3,3,3- trifluoropropanol, or 2,2diflouro propanol.

[0091] Similarly, Form G can be converted to Form H in the presence of halogenated hydrocarbons such as methylene dichloride, chloroform, carbon tetrachloride, preferably methylene dichloride.

[0092] In an exemplary embodiment, the schematic representation of the process for the preparation of compound of formula I is given below:

[0093] HI

[0094] Composition

[0095] In an embodiment, the present invention relates to a plant protection composition comprising i. compound of formula I of form G or form H or, ii. its mixture with a second active compound, and iii. one or more inert additives.

[0096] The plant protection composition may be in the form of a suspension concentrate (SC), granules (GR) in the form of microgranules, spray granules, coated granules and absorption granules, water dispersible granules (WG), water soluble granules (SG), a dispersible concentrate (DC), oil dispersions (OD), wettable powders (WP), water-soluble powders (SP), a water-soluble concentrate (SL), an emulsion concentrate (EC), or a suspoemulsion (SE).

[0097] The plant protection composition may be in the form of an aqueous suspension concentrate or in the form of a non-aqueous suspension concentrate. The plant protection composition may be in the form of a powder or in the form of granules, which are dispersible in water.

[0098] In an embodiment, the composition comprises 5wt. % to 90 wt. % of compound of formula I of form G, preferably 5wt. % to 80 wt. % of compound of formula I of form G, preferably 10 wt. % to 60 wt. % of compound of formula I of form G, preferably 10 wt. % to 50 wt. % of compound of formula I of form G.

[0099] In a further embodiment, the composition comprises 10 wt. % to 40 wt. % of compound of formula I of form G, preferably 10 wt. % to 30 wt. % of compound of formula I of form G.

[0100] In an embodiment, the composition comprises 5wt. % to 90 wt. % of compound of formula I of form H, preferably 5wt. % to 80 wt. % of compound of formula I of form H, preferably 10 wt. % to 60 wt. % of compound of formula I of form H, preferably 10 wt. % to 50 wt. % of compound of formula I of form H.

[0101] In a further embodiment, the composition comprises 10 wt. % to 40 wt. % of compound of formula I of form H, preferably 10 wt. % to 30 wt. % of compound of formula I of form H

[0102] In an embodiment, the plant protection composition may of an aqueous suspension concentrate or in the form of a non-aqueous suspension concentrate and the composition comprises 5wt. % to 90 wt. % of compound of formula I of form G or form H.

[0103] In an embodiment, the plant protection composition may be in the form of a powder or in the form of granules, which are dispersible in water and the composition comprises 5wt. % to 90 wt. % of compound of formula I of form G or form H. The plant protection composition comprises one or more agriculturally acceptable inert additives or adjuvants selected from the group consisting of chelating agents, thickeners, anti -foam agents, pH buffers, antifreeze agents, dispersants, surfactants, emulsifiers, wetting agents or humectants, suspending agents, stabilizers, plant penetrants (or translocators), safeners, spreading agents, compatibility agents, drift retardants, anti-oxidation agents, preservative agents, drift retardants, inverting agents, soil penetrants, UV absorbers, binders, stickers, fertilizers, inert fillers, pigments, colorants, solvents or mixtures thereof.

[0104] In an embodiment, a plant protection composition comprising, i. compound of formula I of form G or form H in the range of 5 wt.% to 90 wt.%, ii. one or more inert additives selected from the group consisting of chelating agents, thickeners, anti-foam agents, pH buffers, antifreeze agents, dispersants, surfactants, emulsifiers, wetting agents or humectants, suspending agents, stabilizers, plant penetrants (or translocators), safeners, spreading agents, compatibility agents, drift retardants, anti-oxidation agents, preservative agents, drift retardants, inverting agents, soil penetrants, UV absorbers, binders, stickers, fertilizers, inert fillers, pigments, colorants, solvents or mixtures thereof

[0105] In an embodiment, suspension concentrates is prepared, using bead milling process. The method is particularly applicable to pesticides that have a low solubility in water. The particle size of the material in the concentrate can be controlled to give particles less than 5 microns (p).

[0106] The effectiveness of pesticides is often related to the size of pesticide particles. Typically, the smaller the particle is, the greater the efficiency due to factors such as increased release rate and more uniform and wider coverage in the application. For this reason there is a need to prepare pesticidal formulations in which the pesticide has a small particle size, preferably less than 5 p. The small particles are typically prepared by grinding the larger particles using one or more conventional grinding techniques such as, for example, air grinding, hammer grinding, compression (jaws, rotating cone, rolls, impact) impact grinding.

[0107] Suspension concentrate pesticidal compositions or aqueous flowable compositions are concentrated suspensions of water-insoluble pesticides and mixtures of pesticides in an aqueous system. The present invention relates to stable such Indaziflam compositions.

[0108] These aqueous compositions frequently contain about 10% to 80%, by weight, of a solid pesticide or mixture of solid pesticides, thereby providing a method for handling those pesticides which are relatively water insoluble in an aqueous medium. Since these types of compositions have the desirable characteristics of a thick liquid, they may be poured or pumped. Thus, some of the problems, like dusting that is possible in solid compositions of wettable powders and granulars, are avoided. Further, these aqueous-based concentrates also have the added advantage of not requiring the use of organic solvents, often present in emulsifiable concentrates.

[0109] For these reasons, it is desirable to formulate pesticides into suspension concentrates or aqueous flowables. However, such formulations have their own problems such as gelling, caking and settling, as well as problems because of the physical and chemical characteristics of the pesticide or mixture of pesticides.

[0110] Surfactants (including dispersing agents and / or wetting agents) suitable in the aqueous suspension compositions include ethylene oxide / propylene oxide condensates, alkyl- aryl- and aryl arylethoxylates and derivatives thereof; lignosulfonates; cresol- and naphthaleneformaldehyde condensates and sulfonates; polycarboxylates and derivatives thereof; and mixtures thereof. In general, anionic polymeries, such as cresol formaldehyde condensates and their sulfonates, naphthalene formaldehyde condensates and their sulfonates and lignosulfonates have been found to minimize crystal formation during storage and as such, are most preferred.

[0111] Suspending agents such as polysaccharide gums like Xanthan gum, guar gum; gum arabic and cellulose derivatives in amounts of about 0.02% to 3.0%, on a weight to volume basis. These aid in stabilizing the by increasing the viscosity of the suspension concentrate from an initial viscosity of about 100 cps to about 1,000 cps or greater prior to cooling.

[0112] In an embodiment, a suspension concentrate of compound of formula I comprises, antifoaming agents, antifreezing agents, surfactants, thickening agents, preservatives, suspending agents.

[0113] Mixture

[0114] In an embodiment, the present invention relates to a plant protection composition comprising i. compound of formula I of form G or form H ii. a second active compound which is a herbicide, and iii. one or more inert additives.

[0115] In an embodiment, the plant protection composition may further comprise one or more herbicide active ingredients selected from the group consisting of aclonifen, acrolein, azafenidin, acifluorfen, azimsulfuron, asulam, acetochlor, atrazine, anilofos, amicarbazone, amidosulfuron, amitrole, aminocyclopyrachlor, aminopyralid, amiprofos-methyl, ametryn, alachlor, alloxydim, ioxynil, isouron, isoxachlortole, isoxaflutole, isoxaben, isoproturon, ipfencarbazone, imazaquin, imazapic, imazapyr, imazamethabenz-methyl, imazamox, imazethapyr, imazosulfuron, indanofan, eglinazine-ethyl, esprocarb, ethametsulfuron-methyl, ethalfluralin, ethidimuron, ethoxysulfuron, ethoxyfen-ethyl, ethofumesate, etobenzanid, endothal-disodium, oxadiazon, oxadiargyl, oxaziclomefone, oxasulfuron, oxyfluorfen, oryzalin, orthosulfamuron, orbencarb, oleic acid, cafenstrole, carfentrazone-ethyl, karbutilate, carbetamide, quizalofop-ethyl, quizalofop-P-ethyl, quizalofop-P-tefuryl, quinoclamine, quinclorac, quinmerac, cumyluron, clacyfos, glyphosate, glufosinate, clethodim, clodinafop-propargyl, clopyralid, clomazone, chlomethoxyfen, clomeprop, cloransulam-methyl, chloramben, chloridazon, chlorimuron-ethyl, chlorsulfuron, chlorthal-dimethyl, chlorthiamid, chlorphthalim, chlorflurenol-methyl, chlorpropham, chlorbromuron, chloroxuron, chlorotoluron, ketospiradox, saflufenacil, sarmentine, cyanazine, cyanamide, diuron, diethatyl-ethyl, dicamba, cycloate, cycloxydim, diclosulam, cyclosulfamuron, cyclopyranil, cyclopyrimorate, dichlobenil, diclofop-P-methyl, diclofop-methyl, dichlorprop, dichlorprop -P, diquat, dithiopyr, siduron, dinitramine, cinidon- ethyl, cinosulfuron, dinoseb, dinoterb, cyhalofop-butyl, diphenamid, difenzoquat, diflufenican, diflufenzopyr, simazine, dimethachlor, dimethametryn, dimethenamid, dimethenamid-P, simetryn, dimepiperate, dimefuron, cinmethylin, sulcotrione, sulfentrazone, sulfosate, sulfosulfuron, sulfometuron-methyl, sethoxydim, terbacil, daimuron, thaxtomin A, dalapon, thiazopyr, tiafenacil, thiencarbazone, tiocarbazil, thiobencarb, thidiazimin, thifensulfuron- methyl, desmedipham, desmetryne, tetflupyrolimet, thenylchlor, tebutam, tebuthiuron, tepraloxydim, tefuryltrione, tembotrione, terbuthylazine, terbutryn, terbumeton, topramezone, tralkoxydim, triaziflam, triasulfuron, triafamone, triallate, trietazine, triclopyr, triclopyr-butotyl, trifludimoxazin, tritosulfuron, triflusulfuron-methyl, trifluralin, trifloxysulfuron, tribenuron- methyl, tolpyralate, naptalam, naproanilide, napropamide, napropamide-M, nicosulfuron, neburon, norflurazon, vernolate, paraquat, halauxifen-benzyl, halauxifen-methyl, haloxyfop, haloxyfop-P, haloxyfop-etotyl, halosafen, halosulfuron-methyl, bixlozone, picloram, picolinafen, bicyclopyrone, bispyribac-sodium, pinoxaden, bifenox, piperophos, pyraclonil, pyrasulfotole, pyrazoxyfen, pyrazosulfuron-ethyl, pyrazolynate, bilanafos, pyraflufen-ethyl, pyridafol, pyrithiobac-sodium, pyridate, pyriftalid, pyributicarb, pyribenzoxim, pyrimisulfan, pyriminobac- methyl, pyroxasulfone, pyroxsulam, phenisopham, fenuron, fenoxasulfone, fenoxaprop, fenoxaprop-P, fenquinotrione, fenthiaprop-ethyl, fentrazamide, phenmedipham, butachlor, butafenacil, butamifos, butylate, butenachlor, butralin, butroxydim, flazasulfuron, flamprop, flamprop-M, primisulfuron-methyl, fluazifop-butyl, fluazifop-P-butyl, fluazolate, fluometuron, fluoroglycofen-ethyl, flucarbazone- sodium, fluchloralin, flucetosulfuron, fluthiacet-methyl, flupyrsulfuron-methyl- sodium, flufenacet, flufenpyr-ethyl, flupropanate, flupoxame, flumioxazin, flumiclorac-pentyl, flumetsulam, fluridone, flurtamone, fluroxypyr, flurochloridone, pretilachlor, procarbazone-sodium, prodiamine, prosulfuron, prosulfocarb, propaquizafop, propachlor, propazine, propanil, propyzamide, propisochlor, propyrisulfuron, propham, profluazol, propoxycarbazone-sodium, profoxydim, bromacil, brompyrazon, prometryn, prometon, bromoxynil, bromofenoxim, bromobutide, florasulam, florpyrauxifen, hexazinone, pethoxamid, benazolin, penoxsulam, heptamaloxyloglucan, beflubutamid, beflubutamid-M, pebulate, pelargonic -acid, bencarbazone, pendimethalin, benzfendizone, bensulide, bensulfuron-methyl, benzobicyclon, benzofenap, bentazone, pentanochlor, pentoxazone, benfluralin, benfuresate, fosamine, fomesafen, foramsulfuron, mecoprop, mesosulfuron-methyl, mesotrione, metazachlor, metazosulfuron, methabenzthiazuron, metamitron, metamifop, DSMA (disodium methanearsonate), methiozolin, methyldymuron, metoxuron, metosulam, metsulfuron-methyl, metobromuron, metobenzuron, metolachlor, S- metolachlor, metribuzin, mefenacet, monosulfuron, monolinuron, molinate, iodosulfuron, iodosulfuron- methyl-sodium, iofensulfuron, lactofen, lancotrione, linuron, rimsulfuron, lenacil, 2,2,2-trichloroacetic acid, 2,3,6-trichlorobenzoic acid, 2,4,5- trichlorophenoxyacetic acid, 2,4-D ((2,4-dichlorophenoxyacetic acid), or the agriculturally acceptable salts of these herbicide active ingredients.

[0116] In an embodiment, the present invention relates to a method of controlling undesired vegetation, comprising the step of applying the plant protection composition to plants, their environment and / or seeds. In an embodiment, the present invention relates to a method of controlling undesired vegetation, comprising the step of applying the plant protection composition to plants, their environment and / or seeds, wherein the composition comprises, i. compound of formula I of form G or form H, or ii. its mixture with a second active compound, and iii. one or more inert additives.

[0117] In an embodiment, the present invention relates to a method of controlling undesired vegetation, comprising the step of applying the plant protection composition to plants, their environment and / or seeds, wherein the composition comprises , i. compound of formula I of form G or form H, or ii. its mixture with a second active compound which is a herbicide, and iii. one or more inert additives.

[0118] In an embodiment, the present invention relates to a method of controlling undesired vegetation, comprising the step of applying the plant protection composition to plants, their environment and / or seeds, wherein the composition comprises , i. compound of formula I of form G or form H, ii. one or more inert additives.

[0119] In an embodiment, the present invention relates to a method of controlling undesired vegetation, comprising the step of applying the plant protection composition to plants, their environment and / or seeds, wherein the composition comprises , i. compound of formula I of form G or form H, ii. its mixture with a second active compound which is a herbicide, and iii. one or more inert additives. In the foregoing, the amount of compound of formula I of form G or form H is present in the range of 5 wt.% to 90 wt.%.

[0120] In an embodiment, the compound of formula I and the second active compound, which is an herbicide, are in the ratio of 1: 30 to 1: 1.

[0121] In an embodiment, the compound of formula I and the second active compound, which is an herbicide, are in the ratio of 1 : any integer or fractional number between 1 and 30.

[0122] In an embodiment, the compound of formula I and the second active compound, which is an herbicide are in the ratio of 1 : any integer or fractional number between 1 and 30 provide a synergistic effect.

[0123] Crops

[0124] The compound of formula I or its combination with a second active compound which is a herbicide as defined in the context of the present invention or the composition according to the present invention have excellent herbicidal activity against a broad spectrum of important harmful monocotyledonous and dicotyledonous harmful plants.

[0125] Specifically, examples may be mentioned of some representatives of the monocotyledonous and dicotyledonous weed flora which can be controlled by the combinations according to the invention, without restricting to certain species.

[0126] Examples of monocotyledonous harmful plants on which the herbicidal combinations and compositions according to the present invention act efficiently are from amongst the genera Hordeum spp., Echinochloa spp., Poa spp., Bromus spp., Digitaria spp., Eriochloa spp., Setaria spp., Pennisetum spp., Eleusine spp., Eragrostis spp., Panicum spp., Lolium spp., Brachiaria spp., Leptochloa spp., Avena spp., Cyperus spp. Axonopris spp., Sorghum spp., and Melinus spp Particular examples of monocotyledonous harmful plants species on which the herbicidal combinations and compositions according to the present invention act efficiently are selected from from amongst the species Hordeum murinum, Echinochloa crus-galli, Poa annua, Bromus rubens L., Bromus rigidus, Bromus secalinus L., Digitaria sanguinalis, Eriochloa gracilis, Setaria faberi, Setaria viridis, Pennisetum glaucum, Eleusine indica, Eragrostis pectinacea, Panicum miliaceum, Lolium multiflorum, Brachiaria platyphylla, Leptochloa fusca, Avena fatua, Cyperus compressus, Cyperus esculentes, Axonopris offinis, Sorghum halapense, and Melinus repens.

[0127] Examples of dicotyledonous harmful plants on which the herbicidal combinations and compositions according to the present invention act efficiently are from amongst the Examples of dicotyledonous harmful plants on which the herbicidal combinations and compositions according to the present invention act efficiently are from amongst the genera Amaranthus spp., Polygonum spp., Medicago spp., Mollugo spp., Cyclospe rmum spp., Stellaria spp., Gnaphalium spp., Taraxacum spp., Oenothera spp., Am sinckia spp., Erodium spp., Erigeron spp., Senecio spp., Lamium spp., Kochia spp. , Chenopodium spp., Lactuca spp., Malva spp., Ipomoea spp., Brassica spp., Sina pis spp., Urtica spp., Sida spp, Portulaca spp., Richardia spp., Ambrosia spp., Cal andrinia spp., Sisymbrium spp., Sesbania spp., Capsella spp., Sonchus spp., Euph orbia spp., Helianthus spp., Coronopus spp., Salsola spp., Abutilon spp., Vicia sp p., Epilobium spp., Cardamine spp., Pieris spp., Trifolium spp., Galinsoga spp., E pimedium spp., Marchantia spp., Solanum spp., Oxalis spp., Metricaria spp., Plan tago spp., Tribulus spp., Cenchrus spp. Bidens spp., Veronica spp., and Hypochaeris spp.

[0128] Particular examples of dicotyledonous harmful plants species on which the herbicidal combinations and compositions according to the present invention act efficiently are selected from amongst the species Amaranthus spinosus, Polygonum convolvulus, Medicago polymorpha, Mollugo verticillata, Cyclospermum leptophyllum, Stellaria media, Gnaphalium purpureum, Taraxacum offscinale, Oenothera laciniata, Amsinckia intermedia, Erodium cicutarium, Erodium moschatum, Erigeron bonariensis, Senecio vulgaris, Lamium amplexicaule, Erigeron canadensis, Polygonum aviculare, Kochia scoparia, Chenopodium album, Lactuca serriola, Malva parviflora, Malva neglecta, Ipomoea hederacea, Ipomoea lacunose, Brassica nigra, Sinapis arvensis, Urtica dioica, Amaranthus blitoides, Amaranthus retroflexus, Amaranthus hybridus, Amaranthus lividus, Sida spinosa, Portulaca oleracea, Richardia scabra, Ambrosia artemisiifolia, Calandrinia caulescens, Sisymbrium irio, Sesbania exaltata, Capsella bursa- pastoris, Sonchus oleraceus, Euphorbia maculate, Helianthus annuus, Coronopus didymus, Salsola tragus, Abutilon theophrasti, Vicia benghalensis L., Epilobium paniculatum, Cardamine spp, Pieris echioides,

[0129] Trifolium spp., Galinsoga spp., Epimedium spp., Marchantia spp., Solanum spp., Oxalis spp., Metricaria matriccarioides, Plantago spp., Tribulus terrestris, Salsola kali, Cenchrus spp., Bidens bipinnata, Veronica spp., and Hypochaeris radicata. Examples of monocotyledonous harmful plants on which the herbicidal combinations and compositions according to the present invention act efficiently are from amongst the genera Hordeum spp., Echinochloa spp., Poa spp., Bromus spp., Digitaria spp., Eriochloa spp., Setaria spp., Pennisetum spp., Eleusine spp., Eragrostis spp., Panicum spp., Lolium spp., Brachiaria spp., Leptochloa spp., Avena spp., Cyperus spp., Axonopris spp., Sorghum spp., and Melinus spp.

[0130] Examples of the crops on which the combinations according to the present disclosure may be used include, but are not limited to, com, rice, wheat, barley, rye, oat, sorghum, cotton, soybean, peanut, buckwheat, beet, rapeseed, sunflower, sugar cane, tobacco, etc.; vegetables: solanaceous vegetables such as eggplant, tomato, pimento, pepper, potato, etc., cucurbit vegetables such as cucumber, pumpkin, zucchini, water melon, melon, squash, etc., cruciferous vegetables such as radish, white turnip, horseradish, kohlrabi, Chinese cabbage, cabbage, leaf mustard, broccoli, cauliflower, etc., Asteraceae vegetables such as burdock, crown daisy, artichoke, lettuce, etc, liliaceous vegetables such as green onion, onion, garlic, and asparagus, ammiaceous vegetables such as carrot, parsley, celery, parsnip, etc., chenopodiaceous vegetables such as spinach, Swiss chard, etc., lamiaceous vegetables such as Perilla frutescens, mint, basil, etc, strawberry, sweet potato, Dioscoreajaponica, colocasia, etc., flowers, foliage plants, turf grasses, fruits: pome fruits such apple, pear, quince, etc, stone fleshy fruits such as peach, plum, nectarine, Primus mume, cherry fruit, apricot, prune, etc., citrus fruits such as orange, lemon, rime, grapefruit, etc., nuts such as chestnuts, walnuts, hazelnuts, almond, pistachio, cashew nuts, macadamia nuts, etc. berries such as blueberry, cranberry, blackberry, raspberry, etc., grape, kaki fruit, olive, plum, banana, coffee, date palm, coconuts, etc. , trees other than fruit trees; tea, mulberry, flowering plant, trees such as ash, birch, dogwood, eucalyptus, Ginkgo boba, lilac, maple, Quercus, poplar, Judas tree, Liquidambar formosana. plane tree, zelkova, Japanese arborvitae, fir wood, hemlock, juniper, Pinus, Picea, and Taxus cuspidate, etc.

[0131] Also here, post-emergence application is preferred.

[0132] Owing to their herbicidal properties, the compositions according to the present invention can be employed for controlling harmful plants in genetically modified crops or crops obtained by mutation / selection. These crops are distinguished as a rule by particular, advantageous properties, such as resistances to herbicidal compositions or resistances to plant diseases or causative agents of plant diseases such as particular insects or microorganisms such as fungi, bacteria or viruses.

[0133] The foregoing description of the embodiments has been provided for purposes of illustration and is not intended to limit the scope of the present disclosure. Individual components of a particular embodiment are generally not limited to that particular embodiment, but are interchangeable. Such variations are not to be regarded as a departure from the present disclosure, and all such modifications are considered to be within the scope of the present disclosure.

[0134] Examples The presently claimed invention is illustrated in detail by non-restrictive working examples, which follow.

[0135] Analytical Methods

[0136] X-ray powder diffractograms (XRD) are recorded on Malvern Panalytical XRD, model Aeris-DY1382, acquisition from 3° to 6O°20 with reflection mode.

[0137] IR measured using Agilent Cary 630.

[0138] Chiral HPLC was done using Waters Alliance with 2998 PDA detector, Bakerbond C-18 column (250 mm X 4.6 mm) pm and Daicel Chiralpak- ADH column (250 mm X 4.6 mm) 5pm.

[0139] Specific rotation-Rudolph research polarimeter, model AP IV, Sample cone. 1% in MDC, wavelength 589, cell temp. 25°C.

[0140] Example- 1

[0141] Synthesis of N-[(1R, 2S)-2, 6-dimethyl-2, 3-dihydro-lH-inden-yl]-6-[l- fluoroethyl]-l, 3, 5-triazine-2-amine with monochlorobenzene (MCB) and Dimethylacetamide (DMAc) as solvent system and Sodium methoxide (NaOMe) as base

[0142] A mixture of (lR,2S)-2,6-dimethyl-2,3-dihydro-lH-inden-l-amine HC1 salt Compound II (99 gm, 0.5 mole, 1 equiv.), was suspended in MCB (Mono chloro benzene)(1000 mL / Mole) and the mixture was stirred to 120°C -130°C under inert atmosphere. 2-cyanoguanidine (63 gm, 0.75 mol, 1.5 equiv.) was added as its solution in DMAc (400mL / M) and continued the heating for additional 6-8 h. Progress of the reaction was monitored by TLC and HPLC. Upon completion, solvents were removed under reduced pressure and the mixture cooled to 25-30°C. Methanol 500mL / Mole was added and sodium methoxide 30% solution (180 gm, 0.75 Mole, 1.5 equiv.) was added slowly to the above reaction mass, followed by addition of methyl-(R)-2-fhiropropionate (Compound IV (80 gm, 0.75 Mol, 1.5 equiv.)) under inert gas atmosphere. The reaction mixture was stirred at 30°C for 8-10 hrs. Progress of the reaction was monitored by HPLC. After completion of the reaction product was isolated by workup. Thus, obtained crude mass was purified by Method A to give 85 % isolated yield.

[0143] Purification Method A:

[0144] Product was purified using Isopropyl alcohol (2mL / g) of crude and heated at 70- 80°C for 45-90 minutes ~ ImL / g solvent distilled off under reduced pressure and then subsequent mixture cooled to 25-30°C and filtered washed with IPA and dried to get pure product.

[0145] HPLC purity >98% and chiral purity >97% with isomeric ratio of 97: 3

[0146] MP: 182-184°C

[0147] Example -2

[0148] Synthesis of N-[(1R, 2S)-2, 6-dimethyl-2, 3-dihydro-lH-inden-yl]-6-[l- fhioroethyl]-l, 3, 5-triazine-2-amine with DMF as solvent and K2CO3 as base: A mixture of (lR,2S)-2,6-dimethyl-2,3-dihydro-lH-inden-l-amine HC1 salt (DMIA. HC1) (3.8 gm, 0.019 mol, 1 equiv.) and 2-cyanoguanidine (2.4 gm, 0.028 mol, 1.5 equiv.), was suspended in 25 ml dimethyl formamide and the mixture was stirred to 120-130°C for 8-12 hr. under inert atmosphere. Progress of the reaction was monitored by TLC and HPLC. Upon completion, the mixture was cooled to 25-30°C. K2CO3 (3.9 gm, 0.028 mol, 1.5 equiv.) was added at once to the above reaction mass, followed by methyl-(R)-2-fluropropionate (2.96 gm, 0.028 mol, 1.5 equiv.) under inert gas atmosphere. The reaction mixture was stirred at 30°C for 8- 10 hrs. At the end of reaction, reaction mass was drawn in water and extracted with methylene dichloride (two times). Methylene dichloride layer was dehydrated and concentrated under vacuum till dryness. Yield obtained 77%. Crude purity 87% , chiral purity >97% with isomeric ratio of 97: 3.

[0149] Product was purified using purification method A

[0150] Example-3 : Synthesis of N-[(1R, 2S)-2, 6-dimethyl-2, 3-dihydro-lH-inden-yl]-6-[l- fluoroethyl]-l, 3, 5-triazine-2-amine with NMP as solvent and K2CO3 as base:

[0151] A mixture of (lR,2S)-2,6-dimethyl-2,3-dihydro-lH-inden-l-amine HC1 salt (3.8 gm, 0.019 mol, 1 equiv.) and 2-cyanoguanidine (2.4 gm, 0.028 mol, 1.5 equiv.), were suspended in 25 ml 1 -Methyl 2-pyrrolidinone and the mixture was stirred to 120-130°C for 8-12 hr. under inert atmosphere. Progress of the reaction was monitored by TLC and HPLC. Upon completion, the mixture was cooled to 25- 30°C. K2CO3 (3.9 gm, 0.028 mol, 1.5 equiv.) was added at once to the above reaction mass, followed by methyl-(R)-2-fluropropionate (2.96 gm, 0.028 mol, 1.5 equiv.) under inert gas atmosphere. The reaction mixture was stirred at 30°C for 8- 10 hrs. At the end of reaction, reaction mass was drawn in water and extracted with methylene dichloride (two times). Methylene dichloride layer was dehydrated and concentrated under vacuum till dryness. Yield obtained 79%. Crude purity 85%, chiral purity >97% with isomeric ratio of 97: 3 Product was purified using purification method A

[0152] Example 4

[0153] Form G ofN-[(lR, 2S)-2, 6-dimethyl-2, 3-dihydro-lH-inden-yl]-6-[l-fluoroethyl]- 1, 3, 5-triazine-2-amine.

[0154] N-[(lR,2S)-2,6-dimethyindan-l-yl]-6-[l-fluoroethyl]-l,3,5-triazine-2,4-diamine (5 g crude) was dissolved in 50 m of MDC and added 2M / M of 12N HC1 and 10 m water. Clear solution observed, concentrated the solvent. Aqueous layer cooled to 5-10°C and pH of the solution shifted to 7-8, using sodium carbonate solution. Solid precipitated out was filtered washed with water and dried in oven.

[0155] MP: 180°C -181°C chiral purity >97% with isomeric ratio of 97: 3

[0156] Example 5

[0157] Form G ofN-[(lR, 2S)-2, 6-dimethyl-2, 3-dihydro-lH-inden-yl]-6-[l-fluoroethyl]- 1, 3, 5-triazine-2-amine

[0158] N-[(lR,2S)-2,6-dimethyindan-l-yl]-6-[l-fluoroethyl]-l,3,5-triazine-2,4-diamine ( 5 gm)- Form H was dissolved in 2,2,2-Trifluoroethanol (70 mb) stir and warmed till it was clear solution., The solvent was distilled off under vacuum leaving a sticky foamy residue. Second lot of 2, 2, 2-Trifluoro ethanol (70 mb) was added and was stired and warmed until clear solution was obtained which was further subjected to distillation to remove the solvent. The process was repeated one more time. At the end of the process a high vacuum was applied and the dried product was obtained , i.e Form G of N-[(lR,2S)-2,6-dimethyindan-l-yl]-6-[(lR-l- fluoroethyl]-l,3,5-triazine-2,4-diamine, chiral purity >97% with isomeric ratio of 97: 3

[0159] Example 6

[0160] Conversion of Form G to Form H of N-[(lR,2S)-2,6-dimethyindan-l-yl]-6-[l- fluoroethyl]-l,3,5-triazine-2,4-diamine

[0161] Form G (2.5 g) was dissolved in 50 ml of methylene dichloride (MDC) and was distill-off until dryness. The step was repeated for 3 times and finally the product was stirred in IPA 1 mL / g at 25-30°C for 15-30 minutes and filtered to get form H, chiral purity >97% with isomeric ratio of 97: 3 MP: 182-183°C

[0162] Example 7

[0163] Telescopic process for N-[(1R, 2S)-2, 6-dimethyl-2, 3-dihydro-lH-inden-yl]-6-[l- fhioroethyl]-l, 3, 5-triazine-2-amine

[0164] In a reactor, 82 g of DMIA was charged along with 350 ml of 1, 4-dioxane. In the same reactor 152-170g of 4M HC1 in 1, 4 dioxane was dosed over a period of 2 h- 3 h maintaining reaction temperature between 10°C and 20°C. The reaction mass was aged at 25°C to 30°C over a period of 2 h-4 h. 1, 4-dioxane was distilled at 100°C-110°C atmospherically at the end to remove traces of the solvent. Further chlorobenzene 500-600 ml was charged into the reactor.

[0165] In another flask cyanoguanidine (63.8 g) was charged and dissolved it was dissolved in DMAC (200-3 OOmL) at 50°C-60°C, this solution was dosed to the reaction mass at 130°C-135°C over a period of (l-2h) and maintained at this temperature till the completion of the reaction. The progress of the reaction was monitored by HPLC.

[0166] The solvents were distilled under reduced pressure 80±5°C. The reaction mass was cooled to 40-45 °C and Methanol (300 mL) was charged and cooled to 25-30°C followed by addition of 25-30% sodium methoxide in methanol (135 g). Finally, methyl (R) 2-fluoropropanoate (82.98g) was charged and the reaction was stirred at ambient temperature till completion of reaction, progress of the reaction was monitored by HPLC. Reaction mass diluted with water (20-25% aq. solution) and stirred, solid mass precipitated which was fdtered and washed with water (I X 200 mL). Product dried in oven at 50-55°C till constant weight.

[0167] Hot slurry of the product was prepared in methanol, fdter and dried at 50-55 °C under vacuum till constant weight. The weight of dried product was in the range of 95-105 g (68 - 78 % yield).

[0168] Example 8

[0169] One pot reaction for N-[(1R, 2S)-2, 6-dimethyl-2, 3-dihydro-lH-inden-yl]-6-[l- fluoroethyl]-l, 3, 5-triazine-2-amine

[0170] In a reactor DMIA hydrochloric acid salt (20 g), cyanoguanidine (11.04g; 1.3M / M) DMAC (50 mL), chlorobenzene (120 mL) was charged at ambient temperature, and the reactor was heated and stirring was started. Approximately 50-55 ml of the solvent was distilled out. Reaction was heated at 130-135 °C till the starting material was consumed (monitored by TLC and HPLC). Once the reaction was complete, the solvent was distilled out under vacuum and the reaction mass was cooled to ambient temperature. Methanol (50 mL) was charged in the reaction vessel, followed by sodium methoxide in methanol (30%) (23.70g), followed by methyl (R) 2-fluoropropanoate (14g). Progress of the reaction was monitored by TLC and HPLC. After completion reaction mass was diluted with water (20-25% aq. Solution) and stirred, the solid which precipitated out was filtered and dried at SO- 55 °C till constant weight. Crude product was suspended in Ethyl acetate 2mL / g and heated at 65°C-70°C for 45 minutes cooled to 15°C and filtered and dried to get 20 g of the pure product. Example 9

[0171] SC formulation of compound of formula I

[0172] Ingredient Quantity

[0173] Compound of formula I 5.0% to 60%

[0174] Antifoaming agents 0.05% to 1.0%

[0175] Anti freezing agent 2.0% to 20.0%

[0176] Surfactants or mixture of surfactants 2.0% to 20.0%

[0177] Thickening agents 0.05% to 3.0%

[0178] Preservatives 0.01% to 1.0%

[0179] Suspending agents 0.05% to 2.5%

[0180] Water upto 100%

[0181] Example 10-13

[0182] Example 10 11 12 13

[0183] Ratio of Compound of 1:5 1: 10 1:20 1:30 formula I Second herbicide

[0184] Other excipients q.s q.s q.s q.s

[0185] Various herbicide combinations were formulated using the above procedure. Composition comprising compounds of formula I and at least one other herbicides were prepared as follows. The second herbicide is admixed with the suspension concentrate composition of compound of formula I prepared in example 9. Further additional thickening agents, preservatives or surfactants, as desired, are added, and this is then packaged as the mixed aqueous suspension concentrate composition.

[0186] Advantages: The present disclosure described hereinabove has several technical advantages including, but not limited to, the realization of a process for the preparation of compound of formula I, that is simple, economic; efficient and environment friendly; provides improved yield and purity of compound of formula I

[0187] The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.

Claims

We Claims,1. A process for preparing a compound of formula I,Compound of formula I comprising, at least the steps of: a) reacting compound of formula II,Compound of formula II where X is an organic acid salt or a mineral acid salt, with 2-cyanoguanidine in the presence of a solvent SI, to produce compound of formula III which is optionally isolated,Compound of formula III where X is an organic acid salt or a mineral acid salt, b) reacting the compound of formula III obtained in step a) with compound of formula IV,Compound of formula IV in the presence of, i. solvent S2, ii. at least one base B,to produce compound of formula I and, c) purifying the compound of formula I obtained in step b).

2. The process as claimed in claim 1, wherein in step a), the solvent SI is selected from N- methyl Pyrrolidone, N, N-diemthyl formamide, dimethyl acetamide, acetonitrile, formamide, monochlorobenzene, dichlorobenzene, dibutyl ether, tetrahydrofuran, 2 methyl- tetrahydrofuran or combinations thereof.

3. The process as claimed in claim 1, wherein in step a), the reaction is carried out at a temperature in the range of 80°C -140°C.

4. The process as claimed in claim 1, wherein in step b), the solvent S2 is selected from N- methyl Pyrrolidone, N, N-diemthyl formamide, dimethyl acetamide, acetonitrile, formamide, monochlorobenzene, dichlorobenzene methanol, ethanol, propanol, dibutyl ether, tetrahydrofuran, 2 methyltetrahydrofuran or combinations thereof.

5. The process as claimed in claim 1, wherein in step b), the base B is selected from metal alkoxide, metal hydroxides, or metal carbonates.

6. The process as claimed in claim 5, wherein the base B is selected from sodium methoxide, sodium ethoxide, potassium tert butoxide, sodium tert butoxide, sodium hydroxide, potassium hydroxide, lithium hydroxide, cesium hydroxide, sodium carbonate, potassium carbonate, cesium carbonate, or lithium carbonate.

7. The process as claimed in claim 1, wherein in step b), the reaction is carried out at a temperature in the range of 25 °C - 60°C.

8. The process as claimed in claim 1, wherein in step c), the purification step comprises, i. suspending compound of formula I obtained in step b) in solvent S3 and adjusting the pH of the solution in the range of 1-2 and adding water to obtain a clear solution, ii. separating the aqueous layer, iii. cooling the aqueous layer to 5°C -10°C and adjusting the pH of the solution in the range of 7-8, andiv. isolating the resulting precipitate to give Form G of compound of formula I.

9. The process as claimed in claim 8, wherein the at least one solvent S3 is selected from is selected from ethyl acetate, isopropyl acetate, butyl acetate, toluene, ether, isopropyl ether, dibutyl ether cyclopentyl methyl ether, toluene, methylene dichloride or methyl cyclohexane.

10. The process as claimed in claim 8, wherein the compound of formula I has one or more analytical parameter selected from the group consisting of, a XRD pattern as indicated in figure 1, a melting point in the range of from 180°C -182°C , an infrared (IR) spectrum with characteristic functional peaks at wavenumbers (±2cm-l) at 823.1, 874.0, 957.3, 1054.7, 1123.6, 1186.4,1250.6,1528.2,1576.7 ,1637.5, 2898.0 ,2949.7 ,3222.3, 3319.5 ,3432.8 cm’1, or chiral purity >97% with isomeric ratio of N-[(lR,2S)-2,6- dimethyindan- 1 -yl] -6-[( 1 R)- 1 -fluoroethyl] - 1 ,3,5 -triazine-2,4- diamine and a N-[(lR,2S)-2,6-dimethyindan-l-yl]-6-[(lS)-l- fluoroethyl]-l,3,5-triazine-2,4-diamine as 97: 3.

11. The process as claimed in claim 8, wherein the compound of formula I has one or more analytical parameter selected from the group consisting of, a XRD pattern as indicated in figure 1, a melting point in the range of from 180°C -182°C , an infrared (IR) spectrum with characteristic functional peaks at wavenumbers (±2cm-l) at 823.1, 874.0, 957.3, 1054.7, 1123.6, 1186.4,1250.6,1528.2,1576.7 ,1637.5, 2898.0 ,2949.7 ,3222.3, 3319.5 ,3432.8 cm’1, or chiral purity >95% with isomeric ratio of N-[(lR,2S)-2,6- dimethyindan- 1 -yl] -6-[( 1 R)- 1 -fluoroethyl] - 1 ,3,5 -triazine-2,4-diamine and a N-[(lR,2S)-2,6-dimethyindan-l-yl]-6-[(lS)-l- fluoroethyl]-l,3,5-triazine-2,4-diamine as 95: 5.

12. The process as claimed in claim 8, wherein the compound of formula I has chiral purity >95% with isomeric ratio of N-[(lR,2S)-2,6-dimethyindan-l- yl]-6-[(lR)-l-fhioroethyl]-l,3,5-triazine-2,4-diamine and a N-[(lR,2S)- 2,6-dimethyindan-l-yl]-6-[(lS)-l-fluoroethyl]-l,3,5-triazine-2,4-diamine as 95 : 5.

13. The process as claimed in claim 8, wherein the compound of formula I has chiral purity >97% with isomeric ratio of N-[(lR,2S)-2,6-dimethyindan-l- yl]-6-[(lR)-l-fhioroethyl]-l,3,5-triazine-2,4-diamine and a N-[(lR,2S)- 2,6-dimethyindan-l-yl]-6-[(lS)-l-fluoroethyl]-l,3,5-triazine-2,4-diamine as 97: 3.

14. The process as claimed in claim 1, wherein in step c), the purification step comprises, i. suspending compound of formula I obtained in step b) in solvent S4 and heating it at 70°C -80°C for a time period of 45-90 min ii. distilling a part of the solvent under reduced pressure, iii. cooling the solution to 25°C -30°C, and iv. isolating the resulting precipitate to give Form H of compound of formula I.

15. The process as claimed in claim 14, wherein the at least one solvent S4 is selected from water, methanol, ethanol, propanol, butanol, isopropanol isobutanol, acetonitrile, or mixture of solvents.

16. The process as claimed in claim 14, wherein the compound of formula I has one or more analytical parameter selected from the group consisting of a XRD pattern as indicated in figure 2, a melting point in the range of from 182°C -184°C, an infrared (IR) spectrum with characteristic functional peaks at wavenumbers (±2cm-l) at 822.4 ,873.8 ,957.2, 1054.1, 1123.3, 1185.6,1250.5, 1527.4, 1576.3, 1638.8, 2898.5, 2950.3, 3224.8, 3319.9, 3433.4 cm-1, orchiral purity >97% with isomeric ratio of N-[(lR,2S)-2,6- dimethyindan- 1 -yl] -6-[( 1 R)- 1 -fluoroethyl] - 1 ,3,5 -triazine-2,4- diamine and a N-[(lR,2S)-2,6-dimethyindan-l-yl]-6-[(lS)-l- fluoroethyl]-l,3,5-triazine-2,4-diamine as 97: 3.

17. The process as claimed in claim 14, wherein the compound of formula I has one or more analytical parameter selected from the group consisting of a XRD pattern as indicated in figure 2, a melting point in the range of from 182°C -184°C, an infrared (IR) spectrum with characteristic functional peaks at wavenumbers (±2cm-l) at 822.4 ,873.8 ,957.2, 1054.1, 1123.3, 1185.6,1250.5, 1527.4, 1576.3, 1638.8, 2898.5, 2950.3, 3224.8, 3319.9, 3433.4 cm’1, or chiral purity >95% with isomeric ratio of N-[(lR,2S)-2,6- dimethyindan- 1 -yl] -6-[( 1 R)- 1 -fluoroethyl] - 1 ,3,5 -triazine-2,4- diamine and a N-[(lR,2S)-2,6-dimethyindan-l-yl]-6-[(lS)-l- fluoroethyl]-l,3,5-triazine-2,4-diamine as 95: 5.

18. The process as claimed in claim 14, wherein the compound of formula I has chiral purity >95% with isomeric ratio of N-[(lR,2S)-2,6- dimethyindan- 1 -yl] -6-[( IR)- 1 -fluoroethyl]- 1 ,3,5-triazine-2,4-diamine and a N- [( 1 R,2S)-2,6-dimethyindan- 1 -yl] -6-[( 1 S)- 1 -fluoroethyl] -1,3,5- triazine-2,4-diamine as 95:5.

19. The process as claimed in claim 14, wherein the compound of formula I has chiral purity >97% with isomeric ratio of N-[(lR,2S)-2,6- dimethyindan- 1 -yl] -6-[( IR)- 1 -fluoroethyl]- 1 ,3,5-triazine-2,4-diamine and a N- [( 1 R,2S)-2,6-dimethyindan- 1 -yl] -6-[( 1 S)- 1 -fluoroethyl] -1,3,5- triazine-2,4-diamine as 97:3.

20. The process as claimed in claim 1, wherein the compound of formula I obtained in step c) is further subjected to solvent recrystallization in the presence of a solvent selected from ethyl acetate, butyl acetate, isopropyl acetate to obtain form H of compound of formula I.

21. The process as claimed in claim 8, wherein form G of compound of formula I is converted to form H of compound of formula I in the presence of halogenated hydrocarbons selected from methylene dichloride, chloroform, carbon tetrachloride.

22. The process as claimed in claim 14, wherein form H of compound of formula I is converted to form G in the presence of fluorinated alcohols such as 2, 2, 2-trifluoroethanol, 2,2-difluoroethanol, 3,3,3- trifluoro propanol, or 2,2diflouro propanol.

23. A plant protection composition comprising, i. compound of formula I of form G or form H as claimed in any one of claims 1 to 16 , or ii. its mixture with a second active compound, and iii. one or more inert additives.

24. The plant protection composition as claimed in claim 23, comprising of 5 wt. % to 90 wt. % of form G or form H of compound of formula I.

25. The plant protection composition as claimed in any one of claims 23 or 24, which is in the form of an aqueous suspension concentrate or in the form of a non-aqueous suspension concentrate.

26. The plant protection composition as claimed in any one of claims 23 or 24, in the form of a powder or in the form of granules, which are dispersible in water.

27. A method of controlling undesired vegetation, comprising the step of applying the plant protection composition as claimed in any one of the claims 23 to 26 to plants, their environment and / or seeds.

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