Palladium-Catalyzed Tsuji-Trost-Type Vinyl Epoxide Cross-Coupling with Umpolung Hydrazones

Recognized as versatile building blocks, vinyl epoxides have been used as electrophiles to generate compounds of high synthetic value. However, selective functionalization of vinyl epoxides via carbon-carbon (C–C) bond formation has been a major challenge for many years due to its unique chemical reactivity. Current methodologies involve transition metal-activated vinyl epoxides with both stabilized and non-stabilized carbon nucleophiles. Procedures involving stabilized carbanions have limited applicability due to the use of pre-functionalized cyano-, sulphonyl or carbonyl derivatives. Non-stabilized carbanions in the form of organometallic reagents have shown to be robust and versatile reagents in C–C bond formation; however, they are employed in superstoichiometric quantities, require the protection of active functional groups, and generate copious amounts of metallic waste. Therefore, the development of alternative mild carbanion sources is highly desired. In this work, we report a highly chemo- and regioselective palladium-catalyzed vinyl epoxide cross-coupling utilizing hydrazones as organometallic equivalents (HOME). Hydrazones, generated from carbonyl-containing renewable feedstocks, enable a more sustainable reaction, and provide an alternative to highly reactive and sensitive unstabilized organometallic reagents. A broad substrate scope, with high functional group tolerance, is demonstrated along with the late-stage functionalization of natural product derivatives.