A straightforward synthesis of both enantiomers of allo-norcoronamic acids and allo-coronamic acids, by asymmetric Strecker reaction from alkylcyclopropanone acetals

Abstract

Methylcyclopropanone hemiacetal (2 S)- 3a underwent the asymmetric Strecker reaction induced by a chiral amine to provide a useful synthesis of enantiomerically pure (1 R,2 S)-(+)- allo-norcoronamic acid 1 in good yield and high enantiomeric excess. From racemic alkyl hemiacetal (±)- 3, the same methodology also constituted a useful way to prepare both (+)- 1 and (−)- 1 and (+)- allo-coronamic acid 2 and its antipode (−)- 2 with good yield and high enantiomeric excess.