TCCA/RSeSeR-Mediated\nSelenoalkoxy of Allenamides via\na Radical Process: Synthesis of Selanyl-allylic N,O-Aminals

An\nefficient TCCA (trichloroisocyanuric acid)/RSeSeR-mediated selenoalkoxy\nof allenamides for the construction of selanyl-allylic N,OA-aminal\nderivatives was developed. The reaction exhibits good functional group\ntolerance and high efficiency, affording the products in good to excellent\nyields. Mechanistic investigations indicated that a selanyl-allylic\nradical intermediate was first formed via the RSe radical added to\nthe central carbon of allenamides, which subsequently furnished highly\nstable selanyl-allylic carbocation intermediate by abstraction of\nan electron by the chlorine radical. Moreover, this is the first report\nof using selenium reagent (RSeCl) to activate allenamides via a radical\nprocess.