Process for the production of 3- {5- 4- (cyclopentyloxy) -2-hydroxybenzoyl -2 - (3-oxo-2-substituted-2,3-dihydro-1,2-benzisoxazol-6 acid ester) -yl) methoxy phenyl} propionic and intermediate for the process

摘要

A method for preparing a phenylpropionic acid derivative represented by the general formula: ** Formula ** wherein R2a represents an alkoxy group; R3b represents a cycloalkyl group; and R5 represents a methyl group that is substituted with one or more optionally substituted phenyl groups, or an optionally substituted oxygen-containing heterocyclic group, or a salt thereof, which comprises: reacting a benzophenone derivative represented by the general formula: * * Formula ** wherein R2a and R3b are defined as before, or a salt thereof, with a derivative of 6- (halomethyl) -1,2- benzisoxazol-3 (2H) -one represented by the general formula: ** Formula ** wherein X represents a halogen atom; and R5 is defined as before; the benzophenone derivative being prepared by oxidation of the methyl-2H-chromen-2-one represented by the general formula: ** Formula ** with manganese dioxide in the presence of sulfuric acid and water to provide 2-oxo-2Hchromenocarbaldehyde represented by the general formula: ** Formula ** then oxidizing the compound by means of a salt of haloso acid to provide 2-oxo-2H-chromenocarboxylic acid represented by the general formula: ** Formula **