PREPARATION OF ETHYL-3'-[((7-CHLORO-2-QUINOLINYL)ETHENYL)PHENYL]-3-OXOPROPANOATE, A KEY INTERMEDIATE FOR MONTELUKAST SODIUM

摘要

A process for preparing ß- ketoester of formula (III) comprises; (a)condensing alkyl 3- formylbenzoate with 7-Chloroquinaldine to give alkyl 3-[((7-chloro-2-quinolinyl) ethenyl)] benzoate; and (b) reacting alkyl 3-[((7-chloro-2-quinolinyl) ethenyl)] benzoate with an alkyl ester in presence of metal hydride/metal alkoxides to obtain a compound ß- ketoester of structural formula (Ill) or (a) condensing isophthalaldehyde with 7-Chloroquinaldine to give Ethyl 3-[((7-chloro-2- quinolinyl) ethenyl)] benzaldehyde (b) reacting Ethyl 3-[((7-chloro-2-quinolinyl) ethenyl)] benzaldehyde with an a-halo ester in presence of a metal catalyst to give Ethyl 3'-[((7-chloro- 2-quinolinyl) ethenyl)phenyl] -3 -hydroxy propanoate; and (c) treating Ethyl 3'-[((7-chloro-2- quinolinyl)ethenyl)phenyl]-3-hydroxy propanoate with Collins reagent in an organic solvent to obtain a compound ß- ketoester of structural formula (III).