Recent Advancements and New Strategies in the Synthesis, Reactivity, and Biological Activity of Indolo[2,3-b] Quinoxaline Derivatives

Indole and quinoxaline are important alkaloids that make up a significant subset of natural products. Many of these alkaloids exhibit biological activity due to their nitrogen-containing structures, which demonstrate notable antiviral, antitumor, antimicrobial, antimalarial, herbicidal, and anti-plasmodial properties. This review focuses on the preparation of heterocycles and bioactive compounds related to indolo[2,3-b] quinoxaline derivatives. It also discusses multiple synthesis methods and their associated biological activities. We cover a wide range of compounds and reagents used in the synthesis of indolo[2,3-b] quinoxaline and its derivatives, with a particular emphasis on their yields. Over 140 compounds are discussed in this review, supported by more than 85 references. Additionally, we explore various chemical reactions, including condensation, cyclization, Suzuki-Miyaura cross-coupling reaction, substitution, alkylation, multi-component reactions, hydrolysis, oxidation, reduction, Mannich base formation, and the Vilsmeier–Haack reaction, and others. Given the significant biological activities of indolo[2,3-b] quinoxaline derivatives, which are found in certain medications, such as the aza-analogues of the cytotoxic agents ellipticine and cryptoleptine, these synthetic methods enable the efficient production of these compounds. This advancement will foster further research into their potential applications in the pharmaceutical industry.