ZnBr 2 /Oxone-mediated ipso -cyclization of N -(3-phenylprop-2-yn-1-yl)aniline.

In this work, a selective synthetic strategy towards 1-azaspiro[4.5]deca-3,6,9-trien-8-ones from N -tosyl- N -(prop-2-yn-1-yl)aniline is developed. The transformation proceeds smoothly in a mixed solvent including acetonitrile and water when ZnBr 2 and Oxone are employed. Mechanism studies show that the reaction proceeds in a regioselective manner via a radical ipso -cyclization pathway.