Visible light induced boryl radical and its application in reduction of unsaturated XO (X = C, N, S) bonds

Abstract

Studies on photoinduced radical reactions have recently flourished. Many strategies have been discovered for radical generation and application in the radical initiated reactions with visible light and without transition metals and organic dyes. A boryl radical is generated by light illumination from 4-cyanopyridine and B₂cat₂ and confirmed by transient absorption (TA) spectroscopy and density functional theory (DFT) studies. The electron donor–acceptor (EDA) complex formed with these two molecules can be excited by visible light and photocleavage of the B–B bond is induced, thus yielding a boryl radical with a long lifetime in aqueous solution. This kind of radical plays a very important role in visible light induced reduction of compounds with an unsaturated double bond X=O (X = C, N, S). A series of neat, fast, and efficient reactions have been well developed as notable methodologies in organic synthesis.