Rhodium( ii )-catalyzed intramolecular formal [4 + 3] cycloadditions of dienyltriazoles: rapid access to fused 2,5-dihydroazepines

Rhodium(II)-catalyzed intramolecular [4 + 3] cycloadditions of dienyltriazoles have been developed, which enable the efficient synthesis of various fused 2,5-dihydroazepines. Mechanistically, the titled reaction proceeds via an interesting tandem cyclopropanation/aza-cope rearrangement.