Process for the preparation of amide intermediates and their use thereof

1. A process for the preparation of a compound of Formula-1 having E/Z isomer content in a ratio of at least 97:3,

wherein R and R′ are independently selected from hydrogen, alkyl, aryl or aralkyl;

the process comprising:

reacting a compound of Formula-2

with a compound of Formula-3

wherein R and R′ are independently selected from hydrogen, alkyl, aryl or aralkyl;

in the presence of an alkali metal alkoxide base in a suitable solvent to provide the compound of Formula-1, wherein the alkoxide base is used in the mole ratio of 0.8 to 2.5 moles with respect to the compound of Formula-2.

2. The process according to claim 1 , wherein the alkali metal alkoxide base is sodium methoxide, potassium methoxide, sodium tertiary butoxide or potassium tertiary butoxide, and the solvent is a polar aprotic solvent, an alcohol solvent, a hydrocarbon solvent, a polar solvent or an ether solvent.

3. The process according to claim 1 , wherein the reaction is carried out at a temperature ranging from −20° C. to 40° C.

4. A process for the preparation of crystalline compound of Formula-1a having E/Z isomer content in a ratio of at least 97:3,

the process comprising:

reacting a compound of Formula-2

with a compound of Formula-3a

in the presence of sodium or potassium tertiary butoxide in tetrahydrofuran at a temperature of −20° C. to 40° C. to provide the compound of Formula-1a, and purifying the compound of Formula-1a with a suitable solvent to provide crystalline compound of Formula-1a.

5. The process of claim 4 , wherein the crystalline compound of Formula-1a is a crystalline Form-I of the compound of Formula-1a and is characterized by its powder X-ray diffractogram having peaks at about 5.56, 7.47. 8.40. 9.78, 14.75, 16.80, 17.46, 18.72, 20.05, 21.13, 21.70, 23.13, 25.57, 31.68 and 45.35±0.2 degrees 2θ; and wherein purifying the compound of Formula-1a comprises:

a) dissolving the compound of Formula-1a in toluene to form a reaction mixture;

b) concentrating the reaction mixture of step (a) followed by co-distillation with cyclohexane to form a residue;

c) adding diisopropylether to the residue;

d) stirring the reaction mixture of step (c);

e) filtering the solid produced in step (d) and washing with diisopropylether; and

f) drying the solid to get the crystalline Form-I of Formula-1a.

6. The process of claim 4 , wherein the crystalline compound of Formula-1a is a crystalline Form-II of the compound of Formula-1a and is characterized by its powder X-ray diffractogram having peaks at about 3.74, 7.37, 8.17, 14.69, 15.05, 17.25, 17.75, 18.42, 18.77, 19.20, 20.59, 22.42, 22.69, 23.67 and 28.01±0.2 degrees 2θ; and wherein purifying the compound of Formula-1a comprises:

a) dissolving the compound of Formula- 1 a in toluene to form a reaction mixture;

b) concentrating the reaction mixture of step (a) followed by co-distillation with cyclohexane to form a residue;

c) adding cyclohexane to the residue;

d) stirring the reaction mixture of step (c);

e) filtering the solid produced in step (d) and washing with cyclohexane; and

f) drying the solid to get the crystalline Form-II of Formula-1a.

7. The process of claim 4 , wherein the crystalline compound of Formula-1a is a crystalline Form-III of the compound of Formula-1a and is characterized by its powder X-ray diffractogram having peaks at about 5.56, 8.43, 9.58, 9.89, 14.65, 15.18, 16.76, 17.43, 18.75, 19.26, 19.90, 20.21, 21.11, 21.63, 22.30, 25.45 and 27.93±0.2 degrees 2θ; and wherein purifying the compound of Formula-1a comprises:

a) dissolving the compound of Formula-1a in an alcohol solvent;

b) adding water to the reaction mixture;

c) filtering the solid produced in step (b) and washing with water; and

d) drying the solid to get the crystalline Form-III of Formula-1a.

8. The process according to claim 4 , further comprising:

a) hydrolyzing a compound of Formula-6

with a suitable base in a suitable solvent, to provide a compound of Formula-7,

b) treating the compound of Formula-7 with dimethylsulfate in presence of a suitable base in a suitable solvent to provide a compound of Formula-8,

c) reacting the compound of Formula-8 with n-butyl amine in presence or absence of a suitable solvent and suitable base to provide a compound of Formula-9,

d) oxidizing the compound of Formula-9 with sodium hypochlorite in presence of a catalyst selected from TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy)/KBr or oxalyl chloride/dimethyl sulfoxide or AZADO(Azaadamantane N-oxyl)/KBr in a suitable solvent to provide the compound of Formula-3a.

9. The process of claim 8 , wherein the compound of Formula-3a is prepared by the process comprising:

a) hydrolyzing the compound of Formula-6 with an alkali metal hydroxide in an ether solvent to provide the compound of Formula-7;

b) treating the compound of Formula-7 with dimethylsulfate in presence of an alkali metal bicarbonate in methanol to provide the compound of Formula-8;

c) reacting the compound of Formula-8 with n-butyl amine in presence or absence of a suitable solvent and suitable base to provide the compound of Formula-9; and

d) oxidizing the compound of Formula-9 with sodium hypochlorite in presence of TEMPO/KBr in a chloro solvent to provide the compound of Formula-3a.

10. The process of claim 8 , wherein the compound of Formula-3a is prepared by the process comprising:

a) hydrolyzing the compound of Formula-6, with a suitable base in a suitable solvent to provide the compound of Formula-7;

b) treating the compound of Formula-7 with dimethylsulfate in presence of a suitable base in methanol to provide the compound of Formula-8;

c) reacting the compound of Formula-8 with n-butylamine in presence or absence of a suitable solvent and suitable base to provide the compound of Formula-9; and

d) oxidizing the compound of Formula-9 with sodium hypochlorite in presence of AZADO/KBr in methylene chloride to provide the compound of Formula-3a.

11. The process of claim 4 , further comprising:

reacting a compound of Formula-6

with n-butyl amine in methanol in the presence or absence of a suitable base to provide a compound of Formula-9,

oxidizing the compound of Formula-9 with sodium hypochlorite in presence of a catalyst selected from TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy)/KBr or oxalyl chloride/dimethyl sulfoxide or AZADO(Azaadamantane N-oxyl)/KBr in a suitable solvent to provide the compound of Formula-3a.

12. The process of claim 8 , wherein the compound of Formula-8 is prepared by the process comprising: reacting the compound of Formula-7 with dimethylsulfate in presence of a suitable base in methanol to provide the compound of Formula-8.

13. The process of claim 4 , wherein the compound of Formula-3a is prepared by the process comprising:

a) reacting a compound of Formula-10

with a suitable base in methanol to provide a compound of Formula-8,

b) reacting the compound of Formula-8 with n-butyl amine in presence or absence of a suitable solvent and suitable base to provide a compound of Formula-9,

c) oxidizing the compound of Formula-9 with sodium hypochlorite in presence of a catalyst selected from TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy)/KBr or oxalyl chloride/dimethyl sulfoxide or AZADO(Azaadamantane N-oxyl)/KBr in a suitable solvent to provide the compound of Formula-3a.

14. The process according to claim 4 , further comprising:

a) reacting a compound of Formula-6

with n-butyl amine in presence of an alkali metal carbonate in methanol to provide a compound of Formula-9,

b) oxidizing the compound of Formula-9 with sodium hypochlorite in presence of a catalyst selected from TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy)/KBr or oxalyl chloride/dimethyl sulfoxide or AZADO(Azaadamantane N-oxyl)/KBr in a suitable solvent to provide the compound of Formula-3a.