Twofold C−H Activation‐Based Enantio‐ and Diastereoselective C−H Arylation Using Diarylacetylenes as Rare Arylating Reagents

Abstract

AbstractC−H bond activation has been established as an attractive strategy to access axially chiral biaryls, and the most straightforward method is direct C−H arylation of arenes. However, the arylating source has been limited to several classes of reactive and bulky reagents. Reported herein is rhodium‐catalyzed 1:2 coupling of diarylphosphinic amides and diarylacetylenes for enantio‐ and diastereoselective construction of biaryls with both central and axial chirality. This twofold C−H activation reaction stays contrast to the previously explored Miura–Satoh type 1:2 coupling of arenes and alkynes in terms of chemoselectivity and proceeded under mild conditions with the alkyne acting as a rare arylating reagent. Both C−H activation events are stereo‐determining and are under catalyst control, with the 2nd C−H activation being diastereo‐determining in a remote fashion. Analysis of the stereochemistry of the major and side products suggests moderate enantioselectivity of the initial C−H activation–desymmetrization process. However, the minor (R) rhodium vinyl intermediate is consumed more readily in undesired protonolysis, eventually resulting in high enantio‐ and diastereoselectivity of the major product.