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

Org Lett. 2022 Nov 11;24(44):8153-8157. doi: 10.1021/acs.orglett.2c03205. Epub 2022 Oct 27.

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.