Rh(III)‐Catalyzed [4 + 3] Annulation for Construction of Heterocycle‐Fused Azepines

A straightforward Rh(III)‐catalyzed [4 + 3] annulation is developed for the construction of heterocycle‐fused azepines from 2‐arylquinazolines and allyl ethers. This protocol leverages sequential CH/NH functionalization to facilitate a β ‐hydride elimination pathway within a seven‐membered rhodacycle intermediate. The mechanistic divergence effectively bypasses the conventional β ‐alkoxy elimination pathway that typically leads to six‐membered ring formation. This approach offers a highly atom‐ and step‐economical route to diversely functionalized azepines with good yields and broad substrate tolerance. The synthetic utility of this approach is shown by the successful incorporation of heteroaromatic and polyaromatic motifs, providing a versatile tool for assembling structurally sophisticated heterocycles.