Modular Construction of Heterobiaryl Atropisomers and Axially Chiral Styrenes via All‐Carbon Tetrasubstituted VQMs

Abstract

AbstractHere we report a new type of chiral all‐carbon tetrasubstituted VQMs generated via chiral phosphoric acids catalyzed nucleophilic addition of 2‐alkynylnaphthols to o‐quinone methides or imines, which can be captured intramolecularly as a result of cycloaddition reaction. A new class of naphthyl‐2H‐chromenes bearing axially and centrally chiral elements and axially chiral quinone‐naphthols were prepared efficiently with good to excellent yields, diastereoselectivities and enantioselectivities. Noteworthy, the enantioselective cycloaddition of alkynylnaphthols with o‐quinone methides proceeded via a [2+2] cycloaddition, followed by a retro‐4π‐electrocyclization and a 6π re‐cyclization. While the cycloaddition of alkynylnaphthols with imines proceeded via a sequential [2+4] cycloaddition and an auto oxidation reaction. Moreover, the obtained axially chiral naphthols can be converted into valuable phosphine ligands and other functional molecules.