Conformationally restricted glutamic acid derivatives: asymmetric synthesis of 4-substituted 4,5-dihydro-3(2H)-pyridazinones

The synthesis of optically pure 4,5-dihydro-3(2H)-pyridazinones substituted at C-4, which can be considered conformationally restricted cyclic Glu derivatives, has been accomplished by the asymmetric γ-alkylation of α,β-unsaturated glutamyl sultams under PTC conditions followed by reaction with hydrazines.