Stereoselective synthesis of highly functionalized cyclobutenes. A facile route to electron-deficient 1,3-dienes

Article abstract of DOI:10.1016/S0040-4020(99)00671-7

Acetoacetanilide undergoes a smooth reaction with triphenylphosphine and dialkyl acetylenodicarboxylates to produce dialkyl 2-(acetoacetanilide-2-yl)- 3-(triphenylphosphoranilidene)-butandioates, which undergo intramolecular Wittig reaction to produce 2-methyl-3-(N-phenylcarbonyl)-1,4- dialkoxycarbonylcyclobutenes. These cyclobutene derivatives undergo electrocyclic ring-opening reactions in boiling toluene to produce highly electron-deficient 1,3-dienes.