One-pot four-component synthesis of tetrahydrofuran derivatives involving an alkyne, an ethylene and two aldehydes via CuCl-mediated reactions of oxazirconacyclopentenes with aldehydes

In the presence of 1 equiv. of CuCl, the reaction of zirconacyclopentenes with 2 equiv. of aldehydes from −78°C to room temperature afforded tetrahydrofuran derivatives in good isolated yields upon hydrolysis with aqueous 3N HCl; oxazirconacycloheptenes, generated in situ from zirconacyclopentenes with one aldehyde, was found to be the reactive intermediate.