Stereoselective Grignard reactions to α-amino nitrones. Synthesis of optically active α-aminohydroxylamines and 1,2-diamines

Article abstract of DOI:10.1016/S0957-4166(97)00250-4

α-Aminohydroxylamines are formed stereoselectively from the nucleophilic addition of phenylmagnesium bromide to α-amino nitrones. In contrast, the addition of methylmagnesium bromide occurs in a stereorandom fashion. Nevertheless it is possible to achieve a complete syn selectivity by diprotecting the α-amino group in the starting nitrone. Hydrogenation of the obtained α-amino hydroxylamines followed by deprotection of the tert-butoxycarbonyl group affords optically active 1,2-diamines.