Cross‐Dehydrogenative Alkynylation: A Powerful Tool for the Synthesis of Internal Alkynes

Abstract

Scheme 1. Selected examples of natural products with triple bonds. Scheme 2. Synthesis of internal alkynes by Sonogashira-coupling and reverse Sonogashira-coupling. Scheme 3. Formation of chemical bonds by cross-dehydrogenative coupling.

Sonogashira coupling of arenediazonium salts: discovery and developments

“…Although the cross-dehydrogenative coupling (CDC), [70][71][72] cross-coupling hydrogen evolution reaction(CCHER), [73][74][75][76] and electrochemical oxidative cross-coupling [77][78][79][80][81] reactions are growing strategies for © AUTHOR(S) direct C-H alkynylation, application of diazonium salts for Sonogashira coupling provides a good alternative for the easy and user-friendly synthesis of diarylacetylenes.…”

Mechanochemically Induced Cross Dehydrogenative Coupling Reactions under Ball Milling

“…Among all types of CÀ H functionalization/activation reactions, the cross dehydrogenative coupling (CDC) reactions have gained much interest in the last decade [39][40][41][42][43][44][45] since their introduction by Li. [43,46] As discussed, this type of coupling reaction allows the construction of a CÀ C bond [43] or CÀ X bond [47] directly from CÀ H-containing substrates in the presence of an oxidant via formal removal of a H 2 molecule.…”

Palladium-Catalyzed Decarbonylative Sonogashira Coupling of Terminal Alkynes with Carboxylic Acids

“…The requirement for presynthesizing those starting materials also greatly decreases the step efficiency and the total atom utilization. Recently, the oxidative C–H alkynylation with terminal alkynes emerges as an alternative method (Scheme B) . However, besides the relatively narrow substrate scope, the oxidative conditions usually lead to the severe homocoupling issues of terminal alkynes.…”

“…In conclusion, we have disclosed an efficient palladium-catalyzed decarbonylative Sonogashira coupling. This is a redox neutral reaction, thus avoided the production of byproduct 1,3-diynes encountered under the oxidative reaction conditions. ,− The substrate scope was also general, i.e., a variety of carboxylic acids and terminal alkynes can be used in this reaction. We believe this reaction is a new relatively general method for preparing internal alkynes from the readily available and environment friendly chemicals.…”