Oxygenation of Simple Olefins through Selective Allylic C−C Bond Cleavage: A Direct Approach to Cinnamyl Aldehydes

A novel metal‐free allylic C?C σ‐bond cleavage of simple olefins to give valuable cinnamyl aldehydes is reported. 1,2‐Aryl or alkyl migration through allylic C?C bond cleavage occurs in this transformation, which is assisted by an alkyl azide reagent. This method enables O‐atom incorporation into simple unfunctionalized olefins to construct cinnamyl aldehydes. The reaction features simple hydrocarbon substrates, metal‐free conditions, and high regio‐ and stereoselectivity.