2-Methyl-5-phenyl-dithiolylium-4-olate

Dithiolylium-4-olate, 5-methyl-2-phenyl-IR, 6, 818 <76CB740, 78CB2021)... 

Since triplet molecular oxygen behaves like a diradical, an interesting reaction has been observed between triplet oxygen and 5-methyl-2-phenyl-l,3-dithiolylium-4-olate (76). Treatment of (76) in acetonitrile with molecular oxygen at room temperature in the dark results in the formation of (80) in 45% yield. 

From the reactions of l,3-dithiolylium-4-olates, for example, (115), with alkenes like A(-phenyl maleimide, acrylonitrile, ethyl acrylate, azirines, a-methyl-styrene, methyl cinnamate, tetra-cyanoethylene, or 2,3-dimethylbut-2-ene, the stable 1 1 adducts, such as (116), are obtained (Equation (15)) <76JOC1724, 78CB3029, 79HCA1236, 79LA360>. 

The mesoionic dithiolylium-4-olates 43 provide examples of both types of cycloadduct. All but one of the derivatives studied react with o-chloranil to give the [4+2] cycloadducts 44 (14—96% yield) the exception is the 2-methyl-5-phenyl derivative 43 (R =Ph, R =Me), which gives the [4+3] cycloadduct 45 (59% yield) (81ZNB609). 

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