I2‑DMSO Mediated Multicomponent [3+2] Annulation Reaction: An Approach to Pyrrolo[2,1‑a]isoquinoline Derivatives with a Quaternary Center

An I2-DMSO mediated multicomponent [3+2] cascade annulation reaction using methyl ketones, 1,2,3,4-tetrahydroisoquinolines (THIQ) and cyclopropenones as readily available substrates has been developed. This metal-free process involves N–H/α-C­(sp3)–H trifunctionalization of THIQ and C–C bond cleavage of cyclopropenone, providing a direct approach to obtain pyrrolo­[2,1-a]­isoquinoline derivatives with a quaternary carbon center. Two C–C bonds and one C–N bond are formed efficiently in one pot.