Facile access to 4-aryl-6-oxycarbonyl-2-pyrones from α-halothioesters with β,γ-unsaturated α-keto esters is achieved via a DBU-promoted Michael addition/lactonization/elimination cascade reaction. The reaction mechanism is tentatively elucidated by control experiments and high-resolution...

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An efficient method for targeting a variety of symmetrical and asymmetrical α‐substituted dithiomalonates (DTMs) is described, utilizing 1H‐imidazole‐1‐carbothioates as reactive acylating agents and MgBr2⋅OEt2/DBU or LiHMDS for soft or hard enolization conditions of thioesters, respectively. The utility of this methodology was demonstrated through the synthesis of the pyridopyrimidine mesoionic insecticides: triflumezopyrim and dicloromezotiaz.