Palladium-Catalyzed C-H Funationalization of Pyridine N-Oxides: Highly Selective Alkenylation and Direct Arylation with Unactivated Arenes

摘要

Transition metal-catalyzed C-H bond functionalization for the C-C bond formation has emerged as a promising area in organic synthesis. In particular, reactions involving Pd-catalyzed activation of sp or sp C-H bonds of arenes or alkanes have been extensively investigated. Successful applications of the C-H activation strategy on readily available substrates have been also reported using various metals other than Pd catalysts.rnPyridine moiety is a key component of pharmacophores, natural products, and synthetic building blocks. Substituted pyridines are usually prepared starting from halo- or metallated pyridyl compounds. However, this "prefunctionalization" route is inevitably accompanied with problems such as the need of extra preparation steps for the frequently unstable precursors and the formation of byproducts.