Recent Developments in Transition Metal‐Free Cross‐Dehydrogenative Coupling Reactions for C–C Bond Formation

Abstract

In recent years, carbon-carbon (C-C) bond formation, by directly connecting two different C-H bonds under oxidative conditions, has attracted much attention in academia and industries. Also known as Cross-Dehydrogenative Coupling (CDC), this methodology is an eco-friendly, cost and step economic as well as superior alternative to classical CC coupling reactions. The catalytic functionalization of C-H bonds using

Synthesis of2H‐benzo[g]furo/thieno/pyrrolo[2,3‐e]indazolesviaIntramolecular Dehydrogenation Photocyclization

“…Most of the photoinduced cross‐dehydrogenative coupling (CDC) reactions needed oxidants or transition metals. [ 24‐25 ] Photochemical organic synthesis in the absence of photocatalysts, oxidant, base and acid has received great attention due to its economic and synthetic value. [ 26 ]…”

Latest Advancements in Transition‐Metal‐Free Carbon‐Heteroatom Bond Formation Reactions via Cross‐ Dehydrogenative Coupling

“…From the perspective of green and sustainable chemistry, transition‐metal‐free CDC has emerged as a convenient one step technique as it avoids the use of toxic metal salts and decreases the production cost [5] . Very recently, we have contributed to the recent advances in construction of carbon‐carbon bond reactions [6] . This account aims to discuss the most important examples of carbon‐heteroatom bond formation reactions under oxidative transition‐metal‐free conditions.…”

“…[5] Very recently, we have contributed to the recent advances in construction of carboncarbon bond reactions. [6] This account aims to discuss the most important examples of carbon-heteroatom bond formation reactions under oxidative transition-metal-free conditions. Depending on the type of CÀ Het bond formed, the review has been divided into four sections: -CÀ N Bond Formation Reactions -CÀ O Bond Formation Reactions -CÀ S Bond Formation Reactions -CÀ P Bond Formation Reactions Furthermore, in view of energetics involved, the bond breaking and formation is mainly governed by two factors.…”

Fe‐Catalyzed Intramolecular Cross‐Dehydrogenative Arylation (CDA), Efficient Synthesis of 1‐Arylnaphthalenes and 4‐Arylcoumarins

“…[22 -34] CÀ H/CÀ H Coupling reactions, which were well-featured as crossdehydrogenative-coupling reactions (CDC), offered a complementary strategy to construct CÀ C bonds from two simple CÀ H bonds directly. [35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52] Among all of the reported transition metals, Fe was brought into focus because of its low toxicity, popular price, and environmentally benign features. [53 -60] Many excellent works of iron-catalyzed CDC reactions involve C(sp 3 )H bond activation have been reported.…”

“…Transition‐metal‐catalyzed C−H bond functionalization could provide a green and economical solution to synthesize valuable products from simple molecules, has been employed as a powerful warhead in the pharmaceutical and chemical industry [22–34] . C−H/C−H Coupling reactions, which were well‐featured as cross‐dehydrogenative‐coupling reactions (CDC), offered a complementary strategy to construct C−C bonds from two simple C−H bonds directly [35–52] . Among all of the reported transition metals, Fe was brought into focus because of its low toxicity, popular price, and environmentally benign features [53–60] .…”