Synthesis of dialkyl 8-oxo-2,8-dihydroisoxazolo[3,2-a]isoindole-2,3-dicarboxylates from dialkyl acetylenedicarboxylates, N-hydroxy phthalimide and tributylphosphine

摘要

Protonation of the highly reactive 1:1 intermediates, produced in the reaction between tributylphosphine and dialkyl acetylenedicarboxylates by N-hydroxy phthalimide leads to vinyltributylphosphonium salts, which undergo electrophilic substitution reaction with conjugate base to produce corresponding stabilized phosphorus ylides. Microwave was found to catalyze conversion of the stabilized phosphorus ylides to dialkyl 8-oxo-2,8-dihydroisoxazolo[3,2-a]isoindole-2,3-dicarboxylates in the presence of solid catalysts in solvent-free conditions.