Initiated pseudo-[3+2] cycloaddition of mixed phosphonium-iodonium ylides to acetonitrile

The oxazole fragment is involved as a structural unit in some biologically active compounds. A large number of oxazole containing compounds were isolated from vari ous natural sources, particularly, of the sea origin. Many of these compounds exhibit different activities, for example, antiviral, antifungal, and antibacterial activities.1,2 An analysis of the published data shows that there are no general approaches to the synthesis of 2,4 and 2,4,5 substituted oxazoles.3—5 Iodonium ylides hold prom ise as reagents for the synthesis of oxazoles.6,7 Recently, we have found that mixed phosphonium iodonium ylides 1 have different reactivities associated primarily with the existence of the enolate resonance form.8—10 An analysis of the structural features of ylide suggests that this compound can be used as a 1,3 dipole in the synthesis of furans 2 according to Scheme 1.