Pyrazolo[1,5-a]pyrimidines are a notable class of heterocyclic compounds with potent protein kinase inhibitor (PKI) activity, playing a critical role in targeted cancer therapy.
A chemodivergent approach has been developed for the synthesis of 3-formylpyrazolo[1,5-a]pyrimidines and methylene-bridged bis(pyrazolo[1,5-a]pyrimidines) employing safe and inexpensive DMSO as a C1 synthon and persulfate as an oxidant.
An efficient and mild approach has been developed for the regio-selective direct C3 halogenation of pyrazolo[1,5-a]pyrimidines employing readily available potassium halide salts and a hypervalent iodine(III) reagent at ambient temperature.
A highly enantioselective Rh-catalyzed reductive dearomatization of pyrazolo[1,5-a]pyrimidines has been realized for the first time by two strategies to afford chiral 4,5,6,7-tetrahydropyrazolo[1,5-a]pyrimidines with excellent enantioselectivities, up to 98% ee.
This review highlights recent developments in the microwave-assisted organic synthesis of N- and O-containing heterocycles with specific examples of pyrazolopyrimidines-, coumarin-, quinoline-, and isatin-based scaffolds and their associated biological activities.