Asymmetric Synthesis of α-Amino Acids and α-N-Hydroxyamino Acids from N-Acylbornane-10,2-sultams: 1-chloro-1-nitrosocyclohexane as a practical [NH] equivalent

Successive treatment of N-acylsultams 3 with sodium hexamethyldisilazide, 1-chloro-1-nitrosocyclohexane ( 1 ), and aq. HCl gave diastereoisomerically pure, crystalline N-hydroxyamino-acid derivatives 5 . These were converted into various amino acids 7 , N-hydroxyamino acids 8 , and an N-Boc-amino acid 9 . (S, S)-Isoleucine ( 17 ) and (S, S)-2-acetamido-3-phenylbutyric acid ( 23 ) were obtained from N-crotonoylsultam 15 via 1,4-addition of an organomagnesium or organocopper reagent followed by enolate ‘amination’ with 1 .