Synthesis of benzofused five-ring sultams via Rh-catalyzed C-H olefination directed by an N-Ac-substituted sulfonamide group.

A Rh-catalyzed N-Ac-sulfonamide group directed C-H olefination-cyclization to afford benzofused five-ring sultam is described with high yield and a wide range of substrate scope. The N-acetyl group is a key for this transformation implying that N-H acidity is the major influence. The acetyl group is removed under mild conditions in excellent yield to provide NH-free sultam that can be transformed into various benzofused five-ring sultam analogues via acylation, nucleophilic substitution, and Mitsunobu alkylation.