Phenylsulfinylselenyl chloride (PhSO ₂ SeCl): a new reagent for the formation of C–Se and N–Se bonds. Generation and in situ Diels–Alder trapping of selenonitrosoarene intermediates (Ar–NSe)

The novel electrophilic selenium transfer reagent phenylsulfinylselenyl chloride, PhSO2SeCl, 3 has been prepared and reacted with enolisable carbonyl compounds to yield α-selenoketones and diselenides; reaction of reagent 3 with arylamines in the presence of triethylamine and dimethylbutadiene affords 1,2-selenazine derivatives, providing the first evidence for Diels–Alder trapping of selenonitroso intermediates, Ar–NSe.