Enantioselective synthesis of β-amino acids. Part 9: Preparation of enantiopure α,α-disubstituted β-amino acids from 1-benzoyl-2( S)- tert-butyl-3-methylperhydropyrimidin-4-one [1, 2

Abstract

Double alkylation of enantiopure N, N-acetal pyrimidinone ( S)- 1, a masked chiral derivative of β-alanine prepared from ( S)-asparagine, proceeds with high stereoselectivity to give C(5) disubstituted adducts (2 S,5 R)- 6, (2 S,5 S)- 6, (2 S,5 R)- 7, and (2 S,5 S)- 7. Acid hydrolysis of these derivatives affords enantiopure α,α-dialkylated β-amino acids ( R)- 8, ( S)- 8, ( R)- 9, and ( S)- 9 in very good yields.