Pyrazine Sulfoxides and Sulfones

DIPYRAZINYL DISULFIDES AND PYRAZINESULFONIC ACID DERIVATIVES (H202) 

The fonnation of such pyrazines by primary synthesis has been covered in Chapters 1 and 2 the meagre literature on their formation by oxidation of pyrazinethiones or pyrazinethiols is mentioned in Section 6.1.2. 

Treatment of 2(l//)-pyrazinone (63) with thionyl chloride and triethylamine appears to give both 2-oxo-l, 2-dihydro-l -pyrazinesulfinyl chloride (64) and 5-oxo- 

A few such pyrazine derivatives have been made by primary synthesis (see Chapters 1 and 2) but the main preparative route is by oxidation of alkylthiopyrazines, discussed in Section 6.2.2.1. 

The remaining minor routes appear to be represented in recent literature only by the reaction of ethyl 2-pyrazinecarboxylate (67) with prelithiated dunethyl sulfoxide (DMSO) in THF at 20°C during 3 h to afford 2-(methylsulfinylacetyl)pyrazine (68) (30%) and by the reaction of chloropyrazines (69) with sodium p-acetamidoben-zenesulfinate to give the corresponding p-acetamidophenylsulfonylpyrazines (70).  

Reactions of alkylsulfinyl- and alkylsulfonylpyrazines also have limited representation in recent literature. Their alcoholysis or phenolysis is covered in Section 5.3.1 other reactions are illustrated in the following examples  

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