Rhodium(II)‐Catalyzed [4+2] Annulation of Ester‐Tethered 1‐Sulfonyl‐1,2,3‐Triazoles and Hexahydro‐1,3,5‐Triazines

Abstract A rhodium(II)‐catalyzed [4+2] annulation of ester‐tethered 1‐sulfonyl‐1,2,3‐triazoles and hexahydro‐1,3,5‐triazines, which features a chemoselective 1,2‐ester migration of α‐imine rhodium carbene intermediates, has been developed. Most of the valuable 1,2,3,4‐tetrahydropyrimidine derivatives were generated in good to excellent yields under mild conditions. Several important derivatization reactions have been performed.