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
I. Yavari et Aa. Esmaili, 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, J CHEM R-S, (11), 1998, pp. 714-715
Protonation of the reactive 1:1 intermediate produced in the reaction betwe
en 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.