Ring Systems Incorporating Thiazole

Apart from the considerable industrial interest shown in the benzothiazole system, new methods of synthesis continue to attract the most interest. Noteworthy among those now reviewed is a new condensation of o-aminobenzenethiol with acetylenes, which results in cleavage of the acetylenic bond. 

The 85-year-old controversy concerning the structures of Hector s, Dost s, and HugershofTs bases has been partially resolved by establishing the structures of several Dost s bases and of two Hugershoff s bases. Confusion over the structures of the products obtained from benzothiazole and dimethyl acetylenedi-carboxylate has finally been resolved. 

Other noteworthy advances in benzothiazole chemistry include the use of 3-methylbenzothiazoline-2-thione as a sulphur-transfer reagent (oxirans - thiirans), the isolation of a Meisenheimer-type adduct when 6-nitrobenzothiazole reacts in the 2-position with methoxide ion, Wasserman s work on the reaction of benzothiazoles with singlet oxygen, and the proof that p-benzoquinone is incorporated into the luciferin of live Japanese fireflies. 

Among other condensed thiazole ring systems, imidazo[2,l-6]thiazoles (tetramisole is a member of this class), thiazolo-pyrimidines, and thiazolo-pyridines continue to attract the most interest. Attention is concentrated on synthesis and biological activity. Unexpectedly, dihydrothiazolo[3,2-a]pyridinium bromide is readily brominated when the pyridine ring has a 3-nitro-substituent but not when it has a 3-amino-substituent. 

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F. Kurzer, Condensed Ring Systems Incorporating Thiazole, in D. R. Hogg, A Specialist Periodical Report Organic Compounds of Sulfphur, Selenium and Tellurium, Vol. 1, S.424, Vol. 2, S.653, Vol. 3, S. 617, The Chemical Society, London 1970-1975. 

Condensed Ring Systems Incorporating Thiazole or Selenazole... 

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