2,3-Dichloroquinoxaline in Cross-coupling Reactions: A Single Substrate, Many Possibilities

Transition metal-catalyzed cross-coupling reactions represent one of the most powerful tools in modern organic chemistry. Due to the relevance of nitrogen heterocyclic compounds for many areas, the development of new and effective methods to afford coupled products from these reagents has become very attractive for organic synthesis. Quinoxaline derivatives encompass one of the most privileged classes of heterocycles, being part of several biologically and technologically relevant compounds. Cross-coupling reactions involving the building block 2,3-dichloroquinoxaline (DCQX) emerge as a promising approach from several synthetic approaches reported for the synthesis of quinoxaline derivatives. The present article consists of a literature review regarding the substrate DCQX as a partner for C-C and C-N cross-coupling reactions. Examples of classical Suzuki- Miyaura, Heck and Sonogashira cross-coupling reactions are presented, as well as other synthetic transformations that lead to the formation of fused polycyclic compounds through heterocyclization processes. Some mechanistic insights are also presented. Notably, most of the publications addressing the subject presented herein are from the last decade, and several of the synthesized compounds are relevant due to their applications in many fields. These features emphasize the relevance of DCQX as a substrate for cross-coupling reactions for organic synthesis.