23-23- Novel Chiral Ligand and Process for Preparing 2S3S-23-dialkyltartaric Acid Employing the Same

摘要

PURPOSE: Provided are a novel (S)-2-t-butyldiphenylsilyloxymethylindoline of the formula(1) and a process for preparing (2S,3S)-2,3-dialkyltartaric acid by pinacol coupling using it as a chiral ligand, thereby producing (2S,3S)-2,3-dialkyltartaric acid in high chemical and optical yields. CONSTITUTION: (S)-2-t-butyldiphenylsilyloxymethylindoline is represented by the formula(1), wherein R is methyl or phenyl, and prepared by the steps of: reducing (S)-indoline-2-carbonic acid into lithium aluminum hydride; reacting it with chloro t-butyldiphenylsilane compound in the presence of imidazole to obtain (S)-2-t-butyldiphenylsilyloxymethylindoline. (2S,3S)-2,3-dialkyltartaric acid is prepared by the steps of: reacting 2-keto carbonic acid with (S)-2-t-butyldiphenylsilyloxymethylindoline(I) in the presence of dicyclohexylcarbodiimide(DDC) to obtain 2-ketoamide(II); pinacol coupling the 2-ketoamide(II) in the presence of hexamethylphosphoamide(HMP) to obtain dialkyltartaric acid derivative; and hydrolyzing the derivative to manufacture (2S,3S)-2,3-dialkyltartaric acid(III).