An unconventional sulfur-to-selenium-to-carbon radical transfer: chemo-and regioselective cyclization of yne-ynamides

An uncommon sulfur → selenium → carbon radical transfer process is employed to develop an unprecedented selenyl radical-mediated regioselective cyclization of yne-tethered-ynamides. Density functional theory studies and HRMS experiments are used to establish a reactivity scale between thiyl and selenyl radicals. The unique features of this transformation include, (1) the chemoselective reactivity of RSe&z.rad; over RS&z.rad;, (2) regioselective RSe&z.rad; attack on alkyne over ynamide, (3) 5- exo -dig cyclization of yne-ynamide to unusual 4-selenyl-pyrroles, and (4) the green synthetic method. The reaction of methyldiselenide with yne-ynamides to methylselenopyrroles is also described. An uncommon sulfur → selenium → carbon radical transfer process is employed to develop an unprecedented selenyl radical-mediated regioselective cyclization of yne-tethered-ynamides.