Rhodium(II)-catalyzed intermolecular [3+2] annulation of N-vinyl indoles with N-tosyl-1,2,3-triazoles via an aza-vinyl Rh carbene

The rhodium(II)-catalyzed annulations of N-vinyl indole derivatives and N-tosyl-1,2,3-triazoles have been developed in this paper, providing a convenient, efficient and straightforward access to synthesize indoles containing a N-dihydropyrrole in moderate to good yields. Furthermore, the reaction of N-vinyl indoles with 2.5 equiv. of N-tosyl-1,2,3-triazoles gave C3-functionalized indoles containing a N-dihydropyrrole in moderate yields after reduction with NaBH3CN in a one-pot manner. This finding gives a new synthetic protocol for the preparation of indoles containing a N-dihydropyrrole under mild conditions.