PATHWAYS FOR THE SYNTHESIS OF PYRIMIDINE AND PYRAN BASED HETEROCYCLIC DERIVATIVES: A CONCISE REVIEW

Abstract

Pyrimidines and pyrans are the special class of heterocyclic compounds with a broad spectrum of biological activities such as anticancer, antiviral, antibacterial, antioxidant, antiallergic and antidepressant. The use of pyran derivatives is not only limitted in cosmetics, pigments and biodegradable agrochemicals but also constitute a structural unit of many natural products. Therefore researchers have synthesized these condensed heterocycles through different complex pathways as target structures for biological studies. This review focuses on the various strategies followed for the convenient synthesis of pyrimidine and pyran based heterocyclic compounds. The steps included condensation followed by cyclization or MCR, either in a step-wise manner or in one pot has been achieved successfully to obtain these two classes of heterocycles under different conditions. Diethyl oxalate, diethyl malonate, malononitrile and ethyl cyanoacetate are the most common reagents used for the synthesis of pyrimidines and pyrans appended on different heterocyclic skeletons.