The Synthesis of Benzazepines via Sequential [3 + 2]-Annulation and [3,3]-Sigmatropic Rearrangement

A novel annulation reaction of prop-2-ynylsulfonium salts with sulfur ylides and nitrosobenzenes has been developed, affording various benzazepines in moderate to good yields. Prop-2-ynylsulfonium salts act as C3 synthons in the reactions, providing a promising benzazepine skeleton in a one-pot operation with readily accessible starting materials.