New Synthesis of Tetraalkyl 2,3-Dihydro-5-oxopyrrolo[2,1-a]isoindole-1,2,3,3-tetracarboxylates and Tetraalkyl 2,3-Dihydro-5-oxopyrrolo[2,1-a]pyrrolidine-1,2,3,3-tetracarboxylates Mediated by Vinyltriphenylphosphonium Salts

Abstract

Protonation of the reactive 1:1 intermediate produced in the reaction between triphenylphosphine and dialkyl acetylenedicarboxylates by CH-acids, such as dialkyl phthalimidomalonates and dimethyl succinimidomalonate, leads to a vinylphosphonium salt, which undergoes intramolecular Wittig reaction to produce the title compounds in fairly high yields.