A series of Z-configured (hetero)aryl and alkylmethylideneisoindolin-1-ones has been efficiently prepared by treatment of N-methoxycarbonylisoindolin-1-ones with a base and reaction with selected aldehydes. The parent N-acylated isoindolin-1-ones have been assembled by a Parham-type cyclization of N-(2-iodoarylmethyl)dicarbamates.