Diels-Alder chemistry of 2-diethoxyphosphinylcyclohex-2-enones. A new approach to complex phosphonates and synthetic applications of the beta-keto phosphonate system

Enone phosphonates 1 and 2 were found to be excellent dienophiles for the Diels-Alder reaction, giving phosphonate-containing polycycles, and the phosphonate group of the resulting adducts facilitated both the installation of an angular alkyl group via a reductive alkylation process and the regioselective generation of a ring junction double bond via an intramolecular Wadsworth-Horner-Emmons reaction.