Ring Opening of Cyclic Vinylogous Acyl Triflates Using Stabilized Carbanion Nucleophiles: Claisen Condensation Linked to Carbon-Carbon Bond Cleavage

Addition of stabilized carbanionic nucleophiles to cyclic vinylouous acyl triflates (VATs) triggers a ring-opening fragmentation to give acyclic beta-keto ester and related products, much like those observed traditionally in the Claisen condensation. Unlike in the classical Claisen condensation, however, the VAT-Claisen reaction described herein is rendered irreversible by C-C bond cleavage, not by deprotonation of the activated methylene product. Full details of this original reaction methodology are disclosed herein, including how subtle differences between the various nucleophiles impact the proper choice of reaction conditions for making 1,3-diketones, beta-keto esters, and beta-keto phosphonates.