Rhodium(I)‐Catalyzed Intermolecular Aza‐[4+3] Cycloaddition of Vinyl Aziridines and Dienes: Atom‐Economical Synthesis of Enantiomerically Enriched Functionalized Azepines

A new synthetic application of vinyl aziridines as N‐containing three‐atom components in a rhodium‐catalyzed [4+3] cycloaddition reaction is described. The reaction proceeds well with various silyl dienol ethers and vinyl aziridines, and enables the efficient synthesis of highly functionalized azepines in an enantioselective manner with net inversion of absolute configuration. The salient features of the transformation include the use of readily available substrates, high selectivity, and mild reaction conditions, as well as the versatile functionalization of the products. Strike a happy medium: The title reaction, in which the vinyl aziridine acts as an aza‐three‐atom component, provided highly functionalized azepines in an enantioselective manner with net inversion of configuration (see scheme; Si is a silyl protecting group). This strategy features the use of readily available substrates, high selectivity, mild reaction conditions, ease of scale‐up, and versatile functionalization of the products.