Ru-, Rh-, and Pd-Catalyzed C−C Bond Formation Involving C−H Activation and Addition on Unsaturated Substrates:  Reactions and Mechanistic Aspects

Terminal Alkyne Coupling Reactions through a Ring: Mechanistic Insights and Regiochemical Switching

“…The transition‐metal‐catalysed dimerisation of terminal alkynes into conjugated enynes is an attractive, atom‐economic method for the preparation of versatile organic building blocks from readily accessible starting materials 1, 2. These reactions involve the formal addition of the C(sp)−H bond of one alkyne across the C≡C bond of the other, a process that can in principle result in three different regio‐ or stereochemical isomers: gem ‐, E ‐, and Z ‐enynes.…”

“…These reactions involve the formal addition of the C(sp)−H bond of one alkyne across the C≡C bond of the other, a process that can in principle result in three different regio‐ or stereochemical isomers: gem ‐, E ‐, and Z ‐enynes. With the additional possibility for the substrates to be consumed through competing metal‐catalysed reaction pathways—for instance leading to butatrienes, arenes, or other polyenes—the widespread application of terminal alkyne coupling reactions in organic synthesis rests on the development of catalysts that can enforce high reaction control 1, 3. Despite the evaluation of a variety of transition‐metal complexes, this remains a largely unfulfilled aspiration, with few catalysts capable of producing single enyne isomers with sufficiently high selectivity 4…”

Cu-catalyzed cross-dehydrogenative coupling: A versatile strategy for C–C bond formations via the oxidative activation of sp 3 C–H bonds

“…The syntheses of these compounds have attracted much attention in industrial and academic research because of their biological and pharmaceutical properties. Recently, some excellent examples based on the direct sp 3 C-H bond activation adjacent to a nitrogen atom for C-C bond formations were reported by Murahashi et al (7), Murai and coworkers (8)(9)(10)(11), Ishii and coworkers (12), Sames and coworkers (13)(14)(15), Davies et al (16,17), Yoshimitsu et al (18), Yoshida and coworkers (19)(20)(21)(22), and Yi and coworkers (23). Although these are elegant methodologies, most of them required another functionalized substrate.…”

Regioselective Catalytic Alkylation of N-Heterocycles in Continuous Flow

“…Currently, the most common catalysts for these type of transformations are Pd, Pt, Rh, Ru, Ir, and Os complexes [4][5][6][7]. These catalysts are expensive, and the reaction normally takes place in the homogeneous phase; accordingly, long and tedious workup is often necessary.…”