Visible-Light-Driven Bifunctional Photocatalytic Radical-Cascade Selenocyanation/Cyclization of Acrylamides with KSeCN

Abstract

A visible-light-induced radical-cascade selenocyanation/cyclization of N -alkyl- N -methacryloyl benzamides, 2-aryl- N -acryloyl indoles, and N -methacryloyl-2-phenylbenzimidazoles with potassium isoselenocyanate (KSeCN) was developed. The reactions were carried out with inexpensive KSeCN as a selenocyanation reagent, potassium persulfate as an oxidant, 2,4,6-triphenylpyrylium tetrafluoroborate as a bifunctional catalyst for phase-transfer catalysis, and photocatalysis. A library of selenocyanate-containing isoquinoline-1,3(2 H,4 H )-diones, indolo[2,1- a ]isoquinoline-6(5 H )-ones, and benzimidazo[2,1- a ]isoquinolin-6(5 H )-ones were achieved in moderate to excellent yields at room temperature under visible-light and ambient conditions. Importantly, the present protocol features mild reaction conditions, large-scale synthesis, simple manipulation, product derivatization, good functional group, and heterocycle tolerance.