2-Alkylisothiazolium salts

Alkylisothiazolium salts (61) undergo N—S bond cleavage when treated with hydrogen sulfide or thiophenol to form acyclic products (62), but 2-aryl compounds give 1,2-dithioles (63 or 64 Scheme 9) (75SST(3)54l, 77SST(4)339). 

Alkylisothiazolium salts 27,45 and 75 were prepared by N-alkylation of isothiazoles 74 with a very wide range of alkyl bromides and iodides, methyl -toluene-sulfonate, methyl trifluoromethansulfonate, methyl fluorosulfonate, dimethylsulfate... 

Isothiazoles react more slowly with nucleophiles than isoxazoles. They are not affected by alkali hydroxides or alkoxides. 2-Alkylisothiazolium salts are more reactive. By the action of aqueous alkali hydroxide, ring-opening occurs with formation of polymeric products. Carbanions cause ring-opening by nucleophilic attack on the S-atom [109], e.g. ... 

The benzenethiolate anion acts primarily as a reducing ag nt with 2-alkylisothiazolium salts (59) simple aliphatic thiols did not react. ... 

The reaction of isothiazolium salts with sulphur in hot pyridine has been studied in detail. If the nitrogen atom carries an aryl substituent, the products can include l,2-dithiole-3-imines. 2-Alkylisothiazolium salts lacking a substituent in the 3-position react with aqueous hydrogen sulphide to... 

Alkylisothiazolium salts are generally stable to oxidizing agents such as hydrogen peroxide and sodium periodate. They are rapidly decomposed by warm alkalis, but no identifiable products were isolable from the resulting tars. They are particularly sensitive towards nucleophilic attack. ... 

Complex Formation.—Suitably substituted 2-alkylisothiazolium salts yield crystalline complexes with heavy-metal salts, including mercury(ii) chloride, lead nitrate, and antimony trichloride. ... 

The interaction of isothiazolium salts and sulphur in boiling pyridine, previously examined in isolated cases, has been studied more systematically. 5-Unsubstituted isothiazolium salts (55) appear to give the corresponding isothiazoline-5-thiones (56). 3-Unsubstituted N-alkylisothiazolium... 

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