Enantioselective Synthesis of Triarylmethanes via Intermolecular C-H Functionalization of Cyclohexadienes with Diaryldiazomethanes.

Rhodium-catalyzed C-H functionalization of cyclohexadiene derivatives with diaryldiazomethanes followed by oxidation with DDQ provides ready access to triarylmethanes. Two chiral dirhodium tetracarboxylates, Rh 2 ( S -PTAD) 4 and Rh 2 ( S -TPPTTL) 4 , were found to be the optimum chiral catalysts for these transformations. This method showcases the ability of diaryldiazomethanes to perform intermolecular C-H insertion with high enantioselectivity and good yields. The method has a broad substrate scope, leading to triarylmethane products with a variety of aryl and heteroaryl substituents, including benzofuran and pyridine heterocycles.