Atom-economical, catalyst-free hydrosulfonation of densely functionalized alkenes: access to oxindole-containing sulfones

An atom-economical hydrosulfonation of densely functionalized alkenes under catalyst-free conditions is described. Alkenes possessing a hydroxy-oxindole moiety underwent hydrosulfonation on treatment with arylsulfinic acids in green media to afford the resulting sulfones in 72-86% yields with excellent diastereoselectivity. A facile, atom-economical, catalyst-free protocol for the hydrosulfonation of densely functionalized alkenes with sulfinic acids in an environmentally benign solvent system at ambient temperature is described.