摘要:
A method for the preparation of an ester of .alpha.-thio-.alpha.-aromatic propionic acid derivatives of the formula: ##STR1## wherein R.sup.1 is alkyl, phenyl or benzothiazolyl, R.sup.2 is alkyl and Ar is an aromatic substituent.The method comprises reacting an ester of .alpha.-chloro-.alpha.-thiopropionic acid of the formula: ##STR2## with an aromatic compound of the formula ARH, in the presence of a Lewis acid. The method provides good reactivity and positional selectivity in the Friedel-Crafts reaction. Many esters of the formula (2) are useful as pharmaceuticals, agricultural chemicals, perfumes or their intermediates.
摘要:
Disclosed is a process for preparing an optical active alkyl ester of .alpha.-(6-methoxynaphth-2-yl)propionic acid from the racemic modification thereof or from a mixture of the optical isomers thereof by preferential crystallization. The efficiency of the optical resolution can be increased by adding a base which facilitates the racemization. The process comprises dissolving the racemic modification or the optical isomers in an organic solvent such as methanol, ethanol, etc., with or without a base such as sodium methoxide, sodium ethoxide, etc., and seeding seed crystals of one of the optical isomers to effect crystallization for optical resolution.