SYNTHESIS OF (E)-ARYLIDENE AND ALLYLIDENE CYCLOPENTANES BY ANNELATION CATALYZED BY A PALLADIUM(0) COMPLEX

When treated with an unsaturated halide in a palladium-catalyzed process, the anions from gamma-acetylenic malonates 4 and 5 stereospecifically lead to cyclopentanes having an exo tri- or tetra-substituted double bond. This reaction which forms simultaneously two carbon-carbon bonds is believed to proceed by nucleophilic attack of the anion on the triple bond activated by the sigma-aryl or sigma-vinyl palladium complex.