A variety of 3-diphenylphosphoryl- and 3-diethoxyphosphoryl-(aza)isoindolinones have been efficiently prepared by aryne- and hetaryne-mediated cyclization of phosphorylated α-amino carbanions derived from suitably substituted 2- and 3-halobenamide and 3-chloropyridine-4-carboxamide derivatives. The synthesis of some 3-sulfonylated analogs by extension of this principle has been achieved.