Stereoselective Synthesis of 2,3-Disubstituted Indoline Diastereoisomers by Chemoenzymatic Processes

Racemic indolines including a variety of structural motifs such as C-2 and C-3 substitutions (alkyl or aryl), cis/trans relative stereochemistry and functionalization of the aromatic ring (fluoro, methyl or methoxy groups) have been efficiently prepared through Fischer indolization and subsequent diastereoselective reduction of the unprotected indoles. Combination of Candida antarctica lipase type A and allyl 3-methoxyphenyl carbonate has been identified as the best tandem for their kinetic resolutions, observing excellent stereodiscriminations for most of the tested indolines.