Asymmetric synthesis of 3-alkyl pipecolic acids

Abstract The Michael addition of R 2 CuLi or R 2 CuMgBr to 4-phenyl-3,4,7,8-tetrahydro-6H-pyrido (2,1-c)(1,4)oxazin-1-one 2 , readily obtained from 2-cyano-6-phenyloxazolopiperidine 1 , led to the formation of alkylated lactones 4a-d in high yield and with complete diastereoselectivity. Transformation of lactones 4a-d to 3-alkyl pipecolic acids was achieved by simple hydrogenolysis.