Thiazolo benzo thio pyrans

Thiazolo[5,4-c]benzo(thio)pyrans.—[C3NS-C5X-C8]. Heterocyclic a-bromo-ketones (326) react with thioureas or thiosemicarbazides in alcoholic acetate-buffered solution to produce 2-substituted 4jEf-thiazolo[5,4-c]-benzo(thio)pyrans (327 X = O or S) in 30—55% yield.  

Naphtho[l,2- /]thiazoles.—[CsNS-Ce-Ce]. Examples of this ring system have been synthesized by an adaptation of conventional methods (see p. 658). 

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