Two Divergent Enyne Cycloisomerization Routes Mediated by Monoallenylidene Pd(II) Catalysts

Abstract

The catalytic application of four monoallenylidene bisphosphine Pd(II) catalysts, which were developed using alkynyl triazole salt as the allenylidene source, in the cycloisomerization of 1,6-enyne was explored. Two divergent reaction pathways, including a new type of intramolecular Alder-ene (IMAE) route and a routine cycloisomerization route, were developed using either complex TAA(Et3P)2-PdCl·BF4 – 3b or TAA(Ph3P)2-PdCl·BF4 – 3c as the catalyst precursor.