-Hydroxylative -Cyclization of -arylpropiolamide.

A facile protocol for the tunable synthesis of 10-hydroxy-1-azaspiro[4.5]deca-3,6,8-trien-2-ones and benzo[]pyrrolo[2,1-][1,4]oxazin-3-ones is described. A tunable synthesis has been realized by the use of ZnBr/oxone and tetra--butylammonium bromide (TBAB)/oxone. The reaction proceeds smoothly with high efficiency and a broad substrate scope. Mechanistic studies indicate that an -protecting group-assisted ortho-trapping reaction is involved. In the transformation, the reaction undergoes α-addition, -cyclization, and ortho-trapping of the resulting spirocyclic species.