Fused and bridged bi- and tri-cyclic lactams via sequential metallo-azomethine ylide cycloaddition–lactamisation

Aldimines of α-amino esters derived from aldehydes bearing an α-, β- or γ-protected amino group undergo AgOAc/R3N catalysed cycloaddition to electronegative olefins (dipolarophile). Subsequent unmasking of the amino group and lactamisation, spontaneous in most cases, generates 5–7 membered fused and bridged bi- and tri-cyclic lactams. The regioselectivity of the lactamisation is controlled by appropriate choice of the dipolarophile.