5-ethyl-2-mercaptothiazole

The cyclization of a-mercaptoketones with ammonium thiocyanate leads to the corresponding 2-mercaptothiazoles (144). For example, 2-mercapto-3-pentanone in ethereal solution with sulfuric acid gives 4-ethyl-5-methyl-2-mercaptothiazole (10), Ri = SH, R2 = Et, R3 = Me, when allowed to stand for 3 hr without heating with ammonium thiocyanate. 

The reaction of carbon oxysulphide with a-aminonitriles results in 5-amino-2-hydroxy thiazoles these are structurally similar to the 2-mercaptothiazoles but are found to be less stable, readily undergoing cleavage or rearrangement to give 4-thiohydantoins. Thus the reaction between ethyl aminocyanoacetate and carbon oxysulphide 31 in ether afforded 5-amino-2-hydroxy-4-carbethoxythiazole 32, which in the presence of aqueous ammonia was converted into 5-carbethoxy-4-thiohydantoin 33. When using sodium... 

Ethyl thiazole-4-carboxylate has been prepared by hy-drogenolysis of ethyl 2-bromothiazole-4-carboxylate with Raney nickel in ethanol, by desulfurization of ethyl 2-mercaptothiazole-... 

Chemical Properties of 1,3,4-Thiadiazoles. Thermal decomposition of cis-(288) proceeds at 50°C to give ( , -Bu C=NN=CHBu, but decomposition of fra s-(288) proceeds only at 145 C, giving (jE )-Bu HC=NNHCOBu and SO, which disproportionates to S and SO2. Several reactions of substituted 2-mercaptothiazoles with chloroacetamides, chlorodiaminotriazines, and ethyl bromoacetate-hydrazine-substituted benzaldehydes, and of 2,5-... 

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