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.

Oxone® Mediated Regioselective C(sp2)−H Selenylation and Thiocyanation of Pyrazolo[1,5‐a]pyrimidines at Room Temperature

“…They also achieved white light‐mediated selenylation of pyrazolo[1,5‐ a ]pyrimidines employing erythrosine‐B as photocatalyst in presence of molecular oxygen (Scheme 1b) [16] . Further this group also demonstrated a photocatalyst‐free white‐light driven protocol for selenylation of pyrazolo[1,5‐ a ]pyrimidines using potassium peroxodisulfate (K 2 S 2 O 8 ) (Scheme 1c) [17] . Recently, our group has also elucidated a blue light‐mediated direct C−H chalcogenation and thiocyanation strategy for 4 H ‐pyrido[1,2‐ a ]pyrimidin‐4‐ones at room temperature in presence of K 2 S 2 O 8 (Scheme 1d) [18] .…”