Asymmetric reactions using the new chiral indoline derivaties

Abstract

Several new indoline and octahydroindole derivatives were synthesized from S-indoline-2-carboxylic acid to use them as chiral auxiliaries and as chiral catalysts in various asymmetric reactions. Diastereoselective reduction ( up to 98 % ee ), alkylation ( up to 98 % ee ), and pinacol coupling reaction ( up to 96 % ee ) of the chiral α-ketoamides 1a and 1b were carried out. The new chiral amide 6b was alkylated with various alkyl halides in high diastereoselectivities ( up to 98 % ee ). Catalytic asymmetric addition of diethylzinc to aldehydes gave the chiral secondary alcohols in high enantiomeric excesses ( up to 97 % ee ) usinf indoline derivatives 6a, 6b, 7a and 7b as chiral catalysts, and the dramatic reversal of the enantiofacial selectivity was observed when octahydroindole derivatives 8a and 8b were used instead of indoline derivatives. Stereocontrolled catalytic asymmetric reductions ( up to 96 % ee ) of alkyl aryl ketones with oxazaborolidines derived from (S)-indoline derivatives 6a and 6b were carried out (S)-indoline derivatives resulted in S-configuration of the secondary alcohols ( up to 96 % ee )and on the contrary, (S)-octahydroindole derivatives 8a and 8b resulted in R- configuration of the secondary alcohols ( up to 90 % ee ).