Recent advancement in the synthesis of diverse spiro-indeno[1,2-b]quinoxalines: a review

Abstract

The nitrogen-containing indeno[1,2-b]quinoxaline ring is a privileged structurally fused active system and has notable applications in various fields of chemistry. For the past several years, it has been recognized as an important building block in organic synthesis. This review summarizes the reactions of indeno[1,2-b]quinoxalinone as a key construction block for producing a variety of indeno[1,2-b]quinoxaline-based spiro-heterocyclic frameworks by means of a wide range of chemical reactions. Most of the reactions described here are multicomponent ones with readily available starting materials that produce complex molecular spiro architectures. Some of the synthesized spiro-indenoquinoxalines exhibit interesting biological activities and have promise for the generation of new drug candidates. Spiro compounds in which two cyclic rings are fused at a common carbon atom are promising interesting skeletal systems in drug discovery due to their unique conformational features, structural complexity and rigidity. The present review aims to highlight the reactions, synthetic strategies and pharmaceutical applications of diverse spiro-indeno[1,2-b]quinoxalines to date.