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

摘要

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. [References: 7]