Silver-Catalyzed Vinylcarbene Insertion into C-C Bonds of 1,3-Diketones with Vinyl--triftosylhydrazones.

We describe the silver-catalyzed formal insertion of a vinylcarbene into unstrained C(CO)-C bonds of 1,3-diketones using vinyl--triftosylhydrazones as vinylcarbene precursors. This method allows the rapid synthesis of otherwise inaccessible 2-vinyl-substituted 1,4-diketones from relatively simple substrates. This mild catalytic protocol exhibits a good functional group tolerance and substrate scope and allows for good chemoselectivity control. The preliminary theoretical calculations suggest that the reaction proceeds through a stepwise enol cyclopropanation/retro-aldol pathway.