Photoinduced Group Transfer Radical Addition of Carbamotelluroates to Acetylenes

[reaction: see text] Te-Phenyl carbamotelluroates 1 add to acetylenes under irradiation of visible light to yield beta-telluroacrylamides 2 regioselectively. This reaction would be initiated by homolytic cleavage of the carbamoyl carbon-tellurium bond, producing carbamoyl and PhTe radicals. The addition reaction proceeds via a radical chain mechanism comprising two processes: (i) addition of carbamoyl radicals at the terminal carbon of the triple bond, giving vinylic radicals, and (ii) S(H)2 reaction on the Te atom caused by the attack of the vinyl radicals to 1.