Palladium-Catalyzed Direct α-Ketoesterification of 8-Methylquinoline Derivatives with α-Ketoacids via Dehydrogenation Coupling Reaction

Abstract

A direct, regiospecific, and efficient palladium-catalyzed α-ketoesterification of 8-methylquinoline derivatives to generate α-ketoesters has been discovered. This reaction is conducted at a mild temperature, free of peroxide, and compatible with air, and various α-ketoesters were achieved with good yields. Importantly, this reaction can be easily amplified to gram level using only 1 mol % of the palladium catalyst, indicating that there is the potential for further reduction of the amount of catalyst loading required for large-scale production.

Pd(II)-Catalyzed Arylation/Oxidation of Benzylic C–H of 8-Methylquinolines: Access to 8-Benzoylquinolines

“…8-Methylquinoline, because of its directing N-atom and ability to form metallacycle complexes, has been found as a good substrate for C­(sp 3 )–H functionalization using various coupling partners. A series of metal-catalyzed C­(sp 3 )–H functionalizations of 8-methylquinolines have been achieved, such as alkenylation, amidation, aminocarbonylation, alkylation, arylation, nitration, amination, α-ketoesterification, fluorination, ethoxycarbonylation, and so on. However, the metal-catalyzed arylation/oxidation of the benzylic C­(sp 3 )–H bond of 8-methylquinoline for the preparation of 8-benzoylquinolines has not been reported.…”

Switchable, Reagent-Controlled C(sp3)-H Selective Iodination and Acetoxylation of 8-Methylquinolines

“…In this field, more challenging site-selective C­(sp 3 )-H activation/functionalization of 8-methylquinoline is especially remarkable. Sanford et al, Daugulis and Shabashov, Yu et al, and other groups have independently developed elegant C­(sp 3 )-H arylation and other C–C, C–N, C–O, or C–Si bond formations of 8-methylquinoline. In this paper, an unprecedented C­(sp 3 )-I formation of 8-methylquinoline by the C­(sp 3 )-H selective activation/functionalization protocol is developed.…”