Rhodium(III)-Catalyzed Coupling of Quinolin-8-carboxaldehydes with CF3–Imidoyl Sulfoxonium Ylides by Chelation-Assisted C(sp2)-H Bond Activation for the Synthesis of Trifluoromethyl-Substituted Enaminones

Abstract

A rhodium(III)-catalyzed aldehydic C(sp²)–H imidoylmethylation of quinolin-8-carboxaldehydes with CF₃-imidoyl sulfoxonium ylides (TFISYs) has been developed for the generation of α-imino ketones, which could be readily tautomerized to enaminones in moderate to excellent yields. In the transformation, TFISYs act as a kind of masked alkenylating reagents for the aldehyde moiety, and the obtained CF₃-enaminone products have been successfully converted into other useful trifluoromethyl-substituted heterocycles.