Design,synthesis,and applications of stereospecific 1,3-diene carbonyls

The strategy toward the synthesis of various 1,3-dienals or 1,3-dienones is disclosed between diazo compounds and furans,which features metal-free,additive-free,broad functional group tolerance,and readily accessible starting materials.Notably,this strategy is applicable in both intramolecular and intermolecular protocols.Mechanistic studies suggested that the reactions undergo a cyclopropanation/rearrangement sequence.With an E/E-1,3-dienal,corresponding N-tosylhydrazones were readily prepared and subjected to phenylboronic acid to form a double bond migration product and indoles to construct a five-member ring via [3 + 2] annulation reaction.