PhSeSiR3-Catalyzed group transfer radical reactions

A novel design for initiating radical-based chemistry in a catalytic fashio n is described. The design of the concept is based on the phenylselenyl gro up transfer reaction from alkyl phenyl selenides by utilizing PhSeSiR3 (1) as a catalytic reagent. The reaction is initiated by the homolytic cleavage of -C-Se- bond of an alkyl phenyl selenide by the in situ generated alkyls ilyl radical (R3Si.), obtained by the mesolysis of PhSeSiR3](.-) (1(.-)). T he oxidative dimerization of counteranion PhSe- to PhSeSePh functions as ra dical terminator. The generation of 1(.-) is achieved by the photoinduced e lectron transfer (PET) promoted reductive activation of 1 through a photosy stem comprising of a visible-light (410 nm)-absorbing electron rich DMA as an electron donor and ascorbic acid as a co-oxidant (Figure 1). The optimum mole ratio between the catalyst 1 and alkyl phenyl selenides for successfu l reaction is established to be 1:10. The generality of the concept is demo nstrated by carrying out variety of radical reactions such as cyclization ( 10, 15-18), intermolecular addition (25), and tandem annulations (32).