Mercaptoketones, condensation, with

Mercaptoketones, condensation, with nitriles (or a-meicapto acids), 158 2-Mercapto-4-methyl-5-carbethoxythiazole, from ammonium dithiocarbamate and a-chloroacetoacetate, 264 2-Mercapto-4-methylthiazole, from chlor-aoetone yield of, 264... 

The reaction of phosphorus pentasulfide with a-acylamino carbonyl compounds of type Ilia also yields thiazoles. Even more commonly, a mercaptoketone is condensed with a nitrile of type IVa or a-mercaptoacids or their esters with Schiff bases. This ring closure is limited to the thiazolidines. In the Va ring-closure type, /3-mercaptoalkylamines serve as the principal starting materials, and ethylformate is the reactant that supplies the carbon at the 2-position of the ring. These syntheses constitute the most important route for the preparation of many thiazolidines and 2-thiazohnes. In the Vb t3fpe of synthesis, one of the reactant supplies only the carbon at the 5-position of the resultant thiazole. Then in these latter years new modern synthetic methods of thiazole ring have been developed (see Section 7 also Refs. 515, 758, 807, 812, 822). 

Cyanamide (227), Rj = NH2, condensed with a-mercaptoketones gives the corresponding 2-aminothiazoles (527). 

Q-Mercaptoketones were condensed with nitriles under a current of dry hydrogen chloride in benzene solution at 0 C... 

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