En Route to Intermolecular Cross-Dehydrogenative Coupling Reactions

Abstract

Cross-coupling reaction between two C−H bonds has become a fundamental strategy in synthetic organic chemistry. With its increasing importance in green chemistry, atom economy, and step economy, its development has skyrocketed within the last 20 years, with the term "crossdehydrogenative coupling (CDC)" popularized and progressed by the group of Li and others to describe direct Y− Z bond formations from Y−H and Z−H bonds under oxidative conditions. Among all types of CDC reactions, the C−C bond formations are of prime importance in building up the molecular complexity but their categorization currently remains disarray due to a wide diversity, resulting in frequent display in separate topics. In this Perspective, a contemporary categorization via C−H activation strategies is presented herein, which could be vital for future CDC designs. With this mechanism-based categorization and discussion, we wish that this minireview will help more synthetic chemists gain insight into the design of CDC reactions and inspires more ideas on this topic.

Transition-Metal-Free Strategies for the Synthesis of C-1 Aryl-Substituted Tetrahydroisoquinolines

“…In order to circumvent these limitations, new shorter and effective methods have been investigated in the recent past. Among them, oxidative coupling 12,13 and lithiation strategies 14 have emerged as direct routes for the synthesis of such compounds. In oxidative coupling, a direct C-H activation enables the use of unfunctionalized substrates, thereby making this approach more sustainable and atom efficient.…”

Metal-Free Direct C–H Functionalization of Quinoxalin-2(1H)-Ones to Produce 3-Vinylated Quinoxalin-2(1H)-Ones in the Presence of Alkenes

“…For Recent years have seen, the emergence of cross-dehydrocoupling (CDC) reaction, between two different molecules, as a prominent research topic (Girard et al, 2014;Huang et al, 2019;Mane et al, 2019;Liu et al, 2020;Xu et al, 2020). These reactions exploit the C-H bonds of various substrates, during the dehydrogenation coupling reactions under oxidizing reaction conditions, to form C-C bonds (Niu et al, 2015;Cheng et al, 2017;Yuan et al, 2018;Xie et al, 2020).…”

Pd-Catalyzed Intermolecular Dehydrogenative Heck Reactions of Five-Membered Heteroarenes

“…We previously reviewed the corresponding literature with references until sep 2010 [10]. Through the DHRs, those of the five-membered heteroarenes have especially retained our attention, and are the subject of the present review which is limited to reports of the last ten years (For more general reviews containing some examples, see [11][12][13][14][15].) The reactions of fused bicyclic heteroarenes that do not involve the C-H bond of the small hetero ring (See examples in [16][17][18]) will be discarded.…”

“…Recently, De Vos' team prepared a palladium-organic framework (noted Pd@ Jia, Xi, and coworkers prepared a heterogeneous catalyst from deposition of PdCl 2 onto the surface of MoS 2 nanosheets [47]. Small amounts of this catalyst mediated the effective C5 alkenylation of 3-ethylthiophene in DMF with Cu(OAc) 2 as oxidant (Equation (15)). The authors did not comment on the catalyst recyclability.…”