Lithium (α-methylbenzyl)allylamide: A differentially protected chiral ammonia equivalent for the asymmetric synthesis of β-amino acids and β-lactams
Davies SG., Fenwick DR.
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- azetidin-2-ones.