Enantioselective Synthesis of Azoniahelicenes by Rh-Catalyzed C–H Annulation with Alkynes

A rhodium­(III)-catalyzed enantio­selective C–H activation/annulation process is disclosed. With a catalyst derived from a chiral CpRh­(III) complex and a chiral acid, the direct annulation reactions between 1-aryl isoquinoline derivatives and alkynes take place smoothly to afford a series of chiral azonia­helicenes in excellent yields and enantio­selectivity (up to 99% yield and 96% ee). Mechanistic studies suggest that C–H bond cleavage may be the turnover-limiting step.