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

An I 2 -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(sp 3 )-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.