Synthesis of 4-(organoselenyl) oxazolones cyclization of -alkynyl ethylcarbamates promoted by organoselenium.

Organoselenyl iodide promoted the intramolecular nucleophilic cyclization of -alkynyl ethylcarbamates in the synthesis of 4-(organoselenyl) oxazolones. The reaction was regioselective, giving the five-membered oxazolone products as the unique regioisomer an initial activation of the carbon-carbon triple bond through a seleniranium intermediate, followed by an intramolecular 5- cyclization mode. The generality of the methodology has been proven by applying the optimized reaction conditions to different organoselenyl iodides and -alkynyl ethylcarbamates having different substituents directly bonded to the nitrogen atom and in the terminal position of the alkyne.