PIDA mediated oxidative annulation of aryl methyl ketones: a facile approach for the chemoselective synthesis of 5-substituted oxazoles.

We have developed a simple and efficient protocol for the chemoselective synthesis of 5-substituted oxazoles via oxidative annulation of substituted acetophenones with NH4OAc and DMSO using PIDA as an effective oxidant. NH4OAc and DMSO act as less toxic one nitrogen and one carbon synthons, respectively. It is a metal-free, step and atom economical approach with good functional group tolerance and chemoselectivity.