Process for the preparation of Rosuvastatin calcium and preparation of its novel intermediates

A process for preparation of the compound of formula (5),

• which comprises the steps of:
• Step 1) reacting (R)-(−)-Ethyl 4-cyano-3-hydroxy butyrate of the formula (1)
• with tert-butyl dimethylsilyl chloride in presence of solvent, selected from the group consisting of dichloromethane, dichloroethane and chloroform, and imidazole at a temperature in the range of 20° C. to 35° C. for the period of 18 hours to 22 hours to obtain (R)-(−)-Ethyl 4-cyano-3-(tertiarybutyldimethylsilyloxy) butyrate of formula (2);
• Step 2) hydrolysing the (R)-(−)-Ethyl 4-cyano-3-(tertiarybutyldimethylsilyloxy) butyrate of formula (2) in presence of solvent, selected from the group consisting of methanol, dichloromethane, dichloroethane and chloroform, and a base, selected from the group consisting of potassium carbonate, sodium bicarbonate, sodium hydride and sodium hydroxide, at a temperature in the range of 8° C. to 18° C. for the period of 2 hours to 4 hours to obtain (R)-4-cyano-3-(tert-butyldimethylsilyloxy) butyric acid of formula (3);
• Step 3) esterifying the (R)-4-cyano-3-(tert-butyldimethylsilyloxy) butyric acid of formula (3) by using catalyst, selected from the group consisting of 4-dimethylaminopyridine, tert-butyl ethyl fumarate and dicyclohexylcarbodiimide, and di-tert-butyl dicarbonate in presence of solvent, selected from the group consisting of t-butanol, dichloromethane, dichloroethane and chloroform, and a base, selected from the group consisting of potassium carbonate, sodium bicarbonate, sodium hydride and sodium hydroxide, at a temperature in the range of 20° C. to 35° C. for the period of 2 hours to 5 hours to obtain (R)-tertiary butyl 4-cyano-3-(tert-butyldimethylsilyloxy) butyrate of formula (4);
• Step 4) converting the (R)-tert-butyl 4-cyano-3-(tert-butyldimethylsilyloxy) butyrate of formula (4) by using hydrogen peroxide in presence of solvent, selected from the group consisting of ethanol, dichloromethane, dichloroethane and chloroform, and a base, selected from the group consisting of potassium carbonate, sodium bicarbonate, sodium hydride and sodium hydroxide, at a temperature in the range of 20° C. to 35° C. for the period of 18 hours to 22 hours to obtain (R)-tert-butyl 4-carbamoyl-3-(tert-butyldimethylsilyloxy) butyrate of formula (5).

A process for the preparation of Rosuvastatin Calcium of formula (I),

• which comprises the steps of:
• Step 1) reacting (R)-(−)-Ethyl 4-cyano-3-hydroxy butyrate of formula (1)
• with tert-butyl dimethylsilyl chloride in presence of solvent, selected from the group consisting of dichloromethane, dichloroethane and chloroform, and imidazole at a temperature in the range of 20° C. to 35° C. for the period of 18 hours to 22 hours to obtain (R)-(−)-Ethyl 4-cyano-3-(tert-butyldimethylsilyloxy) butyrate of formula (2);
• Step 2) hydrolysing the (R)-(−)-Ethyl 4-cyano-3-(tertiarybutyldimethylsilyloxy) butyrate of formula (2) in presence of solvent, selected from the group consisting of methanol, dichloromethane, dichloroethane and chloroform, and base, selected from the group consisting of potassium carbonate, sodium bicarbonate, sodium hydride and sodium hydroxide, at a temperature in the range of 8° C. to 18° C. for the period of 2 hours to 4 hours to obtain (R)-4-cyano-3-(tertiarybutyldimethylsilyloxy) butyric acid of formula (3);
• Step 3) esterifying (R)-4-cyano-3-(tert-butyldimethylsilyloxy) butyric acid of formula (3) by using catalyst, selected from the group consisting of 4-dimethylaminopyridine, tert-butyl ethyl fumarate and dicyclohexylcarbodiimide, and di-tert-butyl dicarbonate in presence of solvent, selected from the group consisting of t-butanol, dichloromethane, dichloroethane and chloroform, and a base, selected from the group consisting of potassium carbonate, sodium bicarbonate, sodium hydride and sodium hydroxide, at a temperature in the range of 20° C. to 35° C. for the period of 2 hours to 5 hours to obtain (R)-tertiary butyl 4-cyano-3-(tertiarybutyldimethylsilyloxy) butyrate of formula (4);
• Step 4) converting the (R)-tertiary butyl 4-cyano-3-(tert-butyldimethylsilyloxy) butyrate of formula (4) by using hydrogen peroxide in presence of solvent, selected from the group consisting of ethanol, dichloromethane, dichloroethane and chloroform, and a base, selected from the group consisting of potassium carbonate, sodium bicarbonate, sodium hydride and sodium hydroxide, at a temperature in the range of 20° C. to 35° C. for the period of 18 hours to 22 hours to obtain (R)-tert-butyl 4-carbamoyl-3-(tert-butyldimethylsilyloxy) butyrate of formula (5);
• Step 5) converting the (R)-tert-butyl 4-carbamoyl-3-(tert-butyldimethylsilyloxy) butyrate of formula (5) by using sodium hypochlorite in presence of solvent, selected from the group consisting of ethanol, dichloromethane, dichloroethane and chloroform, and a base at a temperature in the range of −5° C. to 10° C. for the period of 6 hours to 10 hours to obtain (R)-5-tert-butoxy-3-(tert-butyldimethylsilyloxy)-5-oxopentanoic acid of formula (6);
• Step 6) converting the (R)-5-tert-butoxy-3-(tert-butyldimethylsilyloxy)-5-oxopentanoic acid of formula (6) by using ethyl chloroformate in presence of solvent, selected from the group consisting of toluene, ethanol, dichloromethane, dichloroethane and chloroform, and a base, selected from the group consisting of triethyl amine, potassium carbonate, sodium bicarbonate, sodium hydride or sodium hydroxide, at a temperature in the range of −35° C. to −55° C. for the period of 1 hour to 3 hours to obtain (R)-3-(tert-butyldimethylsilyloxy)-5-ethoxycarbonyloxy-5-oxo-pentanoic acid tert-butyl ester of formula (7);
• Step 7) converting the (R)-3-(tert-butyldimethylsilyloxy)-5-ethoxycarbonyloxy-5-oxo-pentanoic acid tert-butyl ester of formula (7) by using methyl triphenyl phosphonium bromide and organolithium reagent, selected from the group consisting of n-butyllithium, sec-butyllithium and tert-butyllithium, in presence of solvent, selected from the group consisting of tetrahydrofuran, toluene, ethanol, dichloromethane, dichloroethane and chloroform, at a temperature in the range of −5° C. to 5° C. for the period of 1 hour to 3 hours to obtain tert-butyl(3R)-3-(tert-butyldimethylsilyloxy)-5-oxo-6-triphenylphosphorylidene hexanoate of formula (8);
• Step 8) reacting the tert-butyl(3R)-3-(tert-butyldimethylsilyloxy)-5-oxo-6-triphenylphosphorylidene hexanoate of formula (8) with 4-(4-Fluorophenyl)-6-isopropyl-2-(N-methyl-N-methylsulfonylamino)-5-pyrimidinecarboxaldehyde of formula (9)
• in presence of solvent, selected from the group consisting of cyclohexane, toluene, ethanol, dichloromethane, dichloroethane and chloroform, at a temperature in the range of 75° C. to 90° C. for the period of 25 hours to 35 hours to obtain tert-butyl 7-[4-(4-fluorophenyl)-6-isopropyl-2-(N-methyl-N-methylsulfonylamino)pyrimidin-5-yl]-(3R)-3-(tert-butyldimethylsilyloxy)-5-oxo-(E)-6-heptenoate of formula (10);
• Step 9) deprotecting the tert-butyl 7-[4-(4-fluorophenyl)-6-isopropyl-2-(N-methyl-N-methylsulfonylamino)pyrimidin-5-yl]-(3R)-3-(tert-butyldimethylsilyloxy)-5-oxo-(E)-6-heptenoate of formula (10) by using hydrochloric acid in presence of solvent, selected from the group consisting of methanol, ethanol, dichloromethane, dichloroethane and chloroform, at a temperature in the range of 15° C. to 30° C. for the period of 3 hours to 5 hours to obtain tert-butyl 7-[4-(4-fluorophenyl)-6-isopropyl-2-(N-methyl-N-methylsulfonylamino)pyrimidin-5-yl]-(3R)-3-hydroxy-5-oxo-(E)-6-heptenoate of formula (11);
• Step 10) reducing the tertiary butyl 7-[4-(4-fluorophenyl)-6-isopropyl-2-(N-methyl-N-methylsulfonylamino)pyrimidin-5-yl]-(3R)-3-hydroxy-5-oxo-(E)-6-heptenoate of formula (11) by using diethyl methoxy borane and sodium borohydride in presence of solvent, selected from the group consisting of tetrahydrofuran, methanol, ethanol, dichloromethane, dichloroethane and chloroform, at a temperature in the range of −75° C. to −82° C. for the period of 2 hours to 4 hours to obtain tertiary butyl 7-[4-(4-fluorophenyl)-6-isopropyl-2-(N-methyl-N-methylsulfonylamino)pyrimidin-5-yl]-(3R,5S)-dihydroxy-(E)-6-heptenoate of formula (12);
• Step 11) converting the tertiary butyl 7-[4-(4-fluorophenyl)-6-isopropyl-2-(N-methyl-N-methylsulfonylamino)pyrimidin-5-yl]-(3R,5S)-dihydroxy-(E)-6-heptenoate of formula (12) by using aqueous sodium hydroxide in presence of solvent, selected from the group consisting of water, toluene, ethanol, dichloromethane, dichloroethane and chloroform, at a temperature in the range of 20° C. to 35° C. for the period of 2 hours to 4 hours to obtain 7-[4-(4-fluorophenyl)-6-isopropyl-2-(N-methyl-N-methylsulfonylamino)pyrimidin-5-yl]-(3R,5S)-dihydroxy-(E)-6-heptenoic acid sodium salt of formula (13);
• Step 12) converting the 7-[4-(4-fluorophenyl)-6-isopropyl-2-(N-methyl-N-methylsulfonylamino)pyrimidin-5-yl]-(3R,5S)-dihydroxy-(E)-6-heptenoic acid sodium salt of formula (13) by using water and calcium chloride at a temperature in the range of 15° C. to 30° C. for the period of 0.5 hour to 2 hours to obtain 7-[4-(4-fluorophenyl)-6-isopropyl-2-(N-methyl-N-methylsulfonylamino)pyrimidin-5-yl]-(3R,5S)-dihydroxy-(E)-6-heptenoic acid calcium salt of formula (I).