Tandem Isobenzofuran Formation−Diels Alder Reactions in the Coupling of Carbene Complexes with 2-Alkynylbenzaldehyde Derivatives Featuring an Alkyne-Dienophile Tether

2005-06-20T00:00:00Z (GMT) by Yumei Luo James W. Herndon
The coupling of carbene complexes and 2-alkynylbenzaldehyde derivatives has been examined for systems where the alkyne is further linked to an alkene. This reaction proceeds via generation of an isobenzofuran followed by a stereoselective intramolecular Diels−Alder reaction, followed by opening of the resulting oxanorbornene ring. A variety of hydrophenanthrene derivatives and heterocyclic analogues have been produced in this reaction. In one case the intramolecular Pauson−Khand reaction is a competing process.