Recent advances in the synthesis of chromenone fused pyrrolo[2,1-a]isoquinoline derivatives

Both chromenone and pyrrolo[2,1-a]isoquinolines (containing ring-junction nitrogen) are privileged scaffolds in the field of synthetic as well as medicinal chemistry. These fused hybrid moieties are found to be present in diverse natural products like lamellarins and in many biomaterials. Here, we summarize some synthetic methodologies in connection with the synthesis of 2- and 4-chromenones fused to the five-membered ring of pyrrolo[2,1-a]isoquinolines in diverse orientations and their biological significance as reported in the relevant research articles. Several methods for the synthesis of various such fused compounds have been reported in the literature by way of construction of either pyrrole, pyridine, isoquinoline, coumarin (2H-chromen-2-one), 4H-chromen-4-one or more rings simultaneously by the use of eco-friendly classical methods or transition metal-catalyzed methods.