HI-catalyzed intermolecular hydroarylation of alkenyl alcohols with indole nucleophiles to access C3-benzylated indole derivatives

Abstract

A HI-promoted intermolecular hydroarylation of alkenyl alcohols was described. Utilizing a catalytic amount of hydroiodic acid (57 wt % in H₂O), a variety of electron-rich alkenyl alcohols, including 4-arylbut-3-en-1-ols, 4-arylpent-4-en-1-ols, 5-arylhex-5-en-1-ols, and 5-arylpent-4-en-1-ols, efficiently reacted with indole nucleophiles at room temperature to afford C3-benzylated indole derivatives in moderate to good yields. Mechanism experiments suggest that both the direct alkene hydroarylation and a cyclization/nucleophilic ring-opening cascade pathway may synergistically operate, contributing to the high efficiency and regioselectivity of the reaction.