Direct Sulfide-Catalyzed Diastereoselective [4+1] Annulations of ortho-Quinone Methides and Bromides.

Direct sulfide organocatalysis is an emerging topic in research on synthetic chemistry. Here, an unprecedented sulfide-catalyzed diastereoselective [4+1] annulation of (in situ generated) ortho-quinone methides and bromides is reported. Notably, the robustness of such sulfide organocatalysis was demonstrated by performing the catalytic reaction under oxidative conditions without significantly affecting the reaction outcome. Various dihydrobenzofurans with diverse substituents were obtained with high isolated yields of up to 98% and remarkable diastereoselectivity (>19:1 dr in general).