Asymmetric Synthesis of Adamantyl GABA Analogues

Abstract An efficient synthesis of ( R )- and ( S )-4-amino-3-(adamant-1-yl)butyric acids and ( R )- and ( S )-4-(adamant-1-yl)pyrrolidin-2-ones is presented. The synthetic strategy is based on asymmetric Michael addition of diethyl malonate to 1-(adamant-1-yl)-2-nitroethene using available Ni(II) complex as the catalyst. The procedures provide good to high enantioselectivity of Michael addition to sterically hindered nitroalkene and good yields of ( R )- and ( S )-enantiomers of 3-adamantyl substituted GABA.