Copper-Mediated One-Pot Transformation of 2-N-Sulfonyl- aminoaryl Diselenides into Benzo[b][1,4]selenazines

A simple procedure for the one-pot transformation of 2-N-tosylamino diselenides into benzo[b][1,4]selenazines has been established. The data collected indicate that the six-membered heterocyclic ring is the result of a [4+2] cycloaddition reaction of a transient electron-poor o-iminoselenoquinone, acting as diene, with an electron-rich alkene, performing as dienophile. The key step of the synthesis is a 1,4-elimination at selenium of a selenolate ion, leading to the generation of the heterodiene, that requires catalytic amounts of copper(II) trifluoromethanesulfonate, for the activation of the selenium-selenium bond