Synthesis methodology microwave-assisted chemistry

The fourth chapter Quinazoline Alkaloids and Related Chemistry by Shoji Eguchi provides a perspective review focusing on developements of the synthetic methodologies and their synthetic applications. A brief historical background, aza-Wittig methodology, microwave-assisted synthesis, solid-phase... 

Over the last few decades, a wide range of methodologies have been developed for the preparation and manipulation of pyrimidine derivatives. Recently, a microwave-assisted approach to the synthesis of pyrazolo[l,5-n]pyrimidines was reported (Scheme 2.4). Equimolar amounts of the pyrazole and chromen-4-one were heated for 2 min without added solvent. This afforded pyrimidine derivatives that were fairly pure directly from the reaction vessel. Recrystallization from ethanol gave pure materials in excellent yield (88-93%). Since the chemistry was performed neat, the only solvent used was a small amount of ethanol in the purification step, this representing a very clean and straightforward way to generate these valuable materials. 

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