Catalytic Stereoselective Access to Dihydrofuranocarbazoles via a Friedel–Crafts Alkylation/Annulation Sequence

An efficient stereoselective Friedel–Crafts alkylation/annulation sequence between bromonitrostyrenes and hydroxycarbazoles, catalyzed by a bifunctional squaramide, has been developed. This practical protocol provides access to a diverse array of 2,3‐dihydrofuranocarbazoles bearing two adjacent stereogenic centers in moderate to good yields with excellent stereocontrol (up to 84% yield, up to >20:1 dr, 99% ee). The method features mild conditions, broad functional group compatibility, scalability, and applicability to product derivatization. Furthermore, a plausible stereocontrol model based on experimental observations is proposed.