Recent Advances in C–H Bond Functionalization with Ruthenium-Based Catalysts

Abstract

The past decades have witnessed rapid development in organic synthesis via catalysis, particularly the reactions through C–H bond functionalization. Transition metals such as Pd, Rh and Ru constitute a crucial catalyst in these C–H bond functionalization reactions. This process is highly attractive not only because it saves reaction time and reduces waste,but also, more importantly, it allows the reaction to be performed in a highly region specific manner. Indeed, several organic compounds could be readily accessed via C–H bond functionalization with transition metals. In the recent past, tremendous progress has been made on C–H bond functionalization via ruthenium catalysis, including less expensive but more stable ruthenium(II) catalysts. The ruthenium-catalysed C–H bond functionalization, viz. arylation, alkenylation, annulation, oxygenation, and halogenation involving C–C, C–O, C–N, and C–X bond forming reactions, has been described and presented in numerous reviews. This review discusses the recent development of C–H bond functionalization with various ruthenium-based catalysts. The first section of the review presents arylation reactions covering arylation directed by N–Heteroaryl groups, oxidative arylation, dehydrative arylation and arylation involving decarboxylative and sp3-C–H bond functionalization. Subsequently, the ruthenium-catalysed alkenylation, alkylation, allylation including oxidative alkenylation and meta-selective C–H bond alkylation has been presented. Finally, the oxidative annulation of various arenes with alkynes involving C–H/O–H or C–H/N–H bond cleavage reactions has been discussed.

C–H Functionalization of Aromatic Amides

“…The development of economical C–H functionalization methods has always been the aim of researchers’ efforts, and ruthenium catalysts are highly valued by researchers due to their versatility and relatively low price . Moreover, the ruthenium‐catalyzed C–H functionalization with amides as the directing group has been widely used.…”

A Review of some catalysts and promoters used in organic transformations

“…[78,79] As catalyst, ruthenium is capable of performing arylation, alkenylation, alkylation, allylation, oxidative annulations reactions (scheme 10). [80] Ruthenium-catalysed C-C coupling of alkynes and vicinal diols shows high levels of region selectivity. [81] Aldol condensation followed by selective hydrogenation over ruthenium catalyst was proven to be efficient for cyclamen aldehyde synthesis.…”

Conformationally Driven Ru(II)-Catalyzed Multiple ortho-C–H Bond Activation in Diphenylpyrazine Derivatives in Water: Where Is the Limit?

“…Heteroarylation via C-H bond activation has been largely applied to material science, for example, the synthesis of conjugated dyes [8] and polymers [9]. Although Pd [10][11][12][13][14] and Rh [15][16][17][18] catalysts are very efficient in enabling the selective functionalization of C-H bonds, the use of easy-to-prepare, air-stable, often stable in water and functional groups tolerant Ru(II) complexes have attracted much interest in the development of efficient catalytic systems for these processes [19][20][21][22][23][24][25][26]. Despite the ubiquity of C-H bonds in organic molecules, the regioselectivity of C-H bond functionalization can elegantly be controlled by chelation assistance of directing groups [27][28][29][30][31][32].…”