Synthesis of Functionalized α‐Vinyl Aldehydes from Enaminones

An efficient Rh II ‐catalyzed synthesis of functionalized α‐vinyl aldehydes with high E / Z stereoselectivity was developed. The reaction mediates the cyclopropanation of enaminones with vinyl carbenoids that are generated from cyclopropenes in situ to give the aminocyclopropane intermediates. Selective C−C bond cleavage of the cyclopropane intermediates leads to formation of α‐vinyl aldehyde derivatives with high E / Z selectivity. This method proceeds at room temperature under very mild reaction conditions and works with a broad substrate scope.