4- Phenyl-l,2,3,5-dithiadiazolium chloride

Amidines dissolved in dichloromethane at 0°C and under an atmosphere of nitrogen can be in combined with sulfur dichloride (SC12) or disulfur dichloride (S2C12) to easily generate the dithiadiazolium chlorides. Equation (6) illustrates the overall transformation to give 4-phenyl-l,2,3,5-dithiadiazolium chloride 23. Since HC1 is generated... 

The role of nitriles is pivotal to the synthesis of 1,3,2,4-dithiadiazoles, as outlined later in this chapter (Section 6.11.8.2.1). However, it is also possible to make use of this functionality in the 1,2,3,5-series. 4-Trichloromethyl-1,2,3,5-dithiadiazolium chloride 19, 4-phenyl-l,2,3,5-dithiadiazolium chloride 23, and 4- / -butyl-l,2,3,5-dithiadia-zolium chloride 18 can all be prepared from the related nitrile building blocks <1979J(P1)1192>. 

Amidines react with sulfur dichloride or disulfur dichloride in the presence of base to produce the dithiadiazolium chlorides, as illustrated by the preparation of 4-phenyl-l,2,3,5-dithiadiazolium chloride 763 (Scheme 329) <1989CC1134, CHEC-III(6.11.8.1)507>. 

The reaction of benzonitrile with trichlorocyclotrithiazene (732) gives 4-phenyl-l,2,3,5-dithiadiazolium chloride (733)/ Treatment of the sulpho-di-imide Me3SiN=S=NSiMe3 with ClCOSCl yields 5-oxo-5H-l,3A, 2,4-dithiadiazole (734). The action of thionyl chloride on amidoximes (735) affords 1,2,3,5-oxathiadiazole 5-oxides (736) these compounds decompose to sulphur dioxide and carbodi-imides (737) on heating. ... 

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