Lithium (α-methylbenzyl)allylamide: a differentially protected chiral ammonia equivalent for the asymmetric synthesis of β-amino acids and β-lactams

Abstract

The addition products from the highly stereoselective conjugate additions of lithium (αS)-(α-methylbenzyl)allylamide to α, β-unsaturated tert-butyl esters are efficiently deallylated with tris(triphenylphosphine)rhodium(I) chloride and converted, after transesterification to the methyl esters and cyclisation with methylmagnesium bromide, to the corresponding homochiral N-(α-methylbenzyl)-4-substituted-azetidm-2-ones.