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,

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.