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.　[Figure　not　available:　see　fulltext.]　©　2022,　Science　China　Press　and　Springer-Verlag　GmbH　Germany,　part　of　Springer　Nature.