Indane-1,3-dione as a Versatile Intermediate for the Synthesis of 4-azafluorenones

Indane-1,3-dione is a reactive cyclic β-diketone that could be employed for preparing various molecular systems of potential biological applications. Among these, 4- azafluorenones (also known as indeno[1,2-b]pyridines) represent one of the most promising classes of carbocyclic systems. Indeno-fused pyridines possess a wide range of medicinal properties, including anti-proliferative activity and DNA topoisomerase Iα/Iiα inhibitory activity. In this review, we presented all reports from 2000 to 2024 that cover the synthesis of indeno[1,2-b]pyridines and diindeno[1,2-b:2',1'-e]pyridines starting from indane-1,3- dione. The review is classified according to the type of reaction conditions that were applied. Additionally, the reports that are related to the new trends in preparing indenopyridines are indexed in separate sections, including the use of ionic liquids, heterogeneous catalysts, and microwave- and ultrasonic-assisted synthetic routes. Some complex synthetic routes are explained by plausible mechanisms.