STEREOSELECTIVE HALOGENATION IN FRIEDEL-CRAFTS ACYLATION OF 1-ACETYLINDOLINE WITH CHIRAL 2-(METHANESULFONYLOXY)PROPIONYL CHLORIDES

The Friedel-Crafts acylation of 1-acetytindoline with (S)-2- or (R)-2- (methanesulfonyloxy)propionyl chloride, and aluminum chloride in dichl oromethane at room temperature did not afford the expected (S)- or cet yl-5-[2-(methanesulfonyloxy)propionyl]indoline, but gave optically pur e (R)- or (S)-1-acetyl-5-(2-chloropropionyl)indoline, whose stereochem istry at the asymmetric carbon was inverted during the reaction. Simil ar reaction of 1-acetylindoline with the same chiral acylating agents in the presence of aluminum bromide gave mainly the corresponding 2-br omopropionyl derivatives, but as stereo mixtures.