Isothiourea-catalyzed [3 + 3] annulation of α,β-unsaturated esters with sulfoxonium ylides for the synthesis of pyrones.

[Display omitted] A novel isothiourea-catalyzed [3 + 3] annulation of α,β-unsaturated esters with sulfoxonium ylides to synthesize the pyrones has been developed. This transformation could be given the desired product in medium to good yield under mild conditions of reaction. Furthermore, the advantage of this methodology is that have metal free, no base, no oxidant and also no other additives under the conditions. [ABSTRACT FROM AUTHOR]