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.