In the present era the use of fused heterocyclic compounds has been showing a considerable value in the development and designing of new drugs. Article flow through the synthetic strategies highlight on the application of metal-free, visible light mediated catalysis for the fusion of six-membered heterocyclic scaffolds containing nitrogen and sulfur heteroatoms. The power stratagem for the synthesis of diverse fused heterocyclic compounds is the sequencing of multicomponent reactions and subsequent cyclization reactions. The heterocyclic compounds containing Nitrogen and Sulphur atoms exhibit unique properties and are used as potential reactive materials in pharmacokinetic systems. These compounds can also be synthesized considering the high yield, low waste and green synthesis. The main aim of this review is to give an outlook about the synthetic feasibility of fused heterocyclic system and to development an innovative heterocyclic synthetic scheme that allow for different bond forming strategies which are having a significant impact in the pharmaceutical industry, especially the pyrimido-thiazine derivatives in the future synthetic heterocyclic chemistry. The future of Heterocyclic chemistry is development of robust synthetic routes which can generate bulk quantity of desired products and accelerate the drug development process.