Microwave Synthesis of Guanine and Purine Analogs

Microwave radiation, an electromagnetic radiation, is widely used as a source of heating in organic synthesis. Since the discovery of the microwave heating approach, microwave-assisted reaction has emerged as a new green-method in organic synthesis as it provides fast, higher yields, and higher product purities, and it reduces pollution of the environment. The purine ring system possesses undisputed biological importance and it is considered to be one of the most important heterocyclic rings in nature. Therefore, organic chemists have been engaged in extensive efforts to produce these compounds following various greener techniques, primarily to circumvent growing environmental concerns. This topic has received increasing interest owing to the wide variety of purine analogs as biologically significant drugs, and products for industrial application. In this review, we discuss only the microwave-assisted synthesis of purine and guanine analogs, and includes the syntheses of (i) imidazopyrimidines, (ii) pyrazolopyrimidines, (iii) imidazopyridines, and pyrazolopyridines (iv) via microwave.