I2-Catalyzed three-component synthesis of 3-selenylated pyrazolo[1,5-a]pyrimidines

Abstract

A straightforward protocol has been developed to access 3-selenylated pyrazolo[1,5-a]pyrimidines from readily available amino pyrazoles, chalcones, and diaryl/dialkyl diselenides. This I₂-catalyzed methodology is highly useful for synthesizing a wide range of functionalized 3-(aryl/alkylselanyl)pyrazolo[1,5-a]pyrimidine derivatives. Mechanistic investigation disclosed that iodine catalysis is very important in both the cyclization process as well as in the C–H selenylation step. Moreover, the developed reaction conditions are also applicable for the cyclization of amino pyrazole with enaminone followed by C–H selenylation in one pot. The use of simple reagents and catalyst, wide substrate scope, mild and metal-free reaction conditions, and practical applicability are the attractive facets of this approach.