Photocatalyst-Free Visible-Light-Promoted C–H Selenylation of Pyrazolo[1,5-a]pyrimidines

Abstract A new method has been developed for the C–H selenyl­ation of pyrazolo[1,5-a]pyrimidine derivatives under the irradiation of visible light. This photocatalyst-free strategy is applicable to a wide range of pyrazolo[1,5-a]pyrimidines with broad functionalities. The salient features of the method are mild reaction conditions, use of bench-stable oxidant, high regioselectivity, and scalability.