FDA approved six-membered ring fused pyrimidine-based derivatives

Pyrimidine-based derivatives play a vital role in the development of drugs due to their indispensable role in various biological processes. To date, ring fused pyrimidine-based derivatives have been reported to exhibit numerous biological activities including anticancer, antiviral, antianginal, anti-HIV, antifungal, antibacterial, anti-inflammatory, antitubercular and many others. There are numerous synthetic approaches available for the synthesis of fused pyrimidine-based derivatives which provides ample scope in the development of new drugs. Considering these medicinal attributes of fused pyrimidine-based derivatives, we have put forth this book chapter mainly focusing on the FDA approved six-membered ring fused pyrimidine-based derivatives. The present chapter deals with improved synthetic schemes, their biological importance and the adverse effects of FDA approved six-membered ring fused pyrimidine-based drugs. Covering all these aspects may lighten the researchers with the updated literature exploring the best synthetic routes and can think of alternative synthetic routes with less time consuming and non-toxic solvents.