Russian Chemical Bulletin, International Edition, Vol. 60, No. 5, pp. 882—888, May, 2011 882 Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 862—868, May, 2011. 1066-5285/11/6005-882 © 2011 Springer Science+Business Media, Inc. Synthesis of imidazolyl dithiocarbamates and their reactions with phenacyl bromides* O. S. El´tsov, V. S. Mokrushin, M. V. Smirnova, and M. Z. Shafikov Ural Federal University named after the first President of Russia B. N. Yeltsin, 19 ul. Mira, 620002 Ekaterinburg, Russian Federation. Fax: +7 (343) 374 5483. E-mail: oleg-eltsov@yandex.ru The reactions of ethyl (5-carbamoyl-3H-imidazol-4-yl)dithiocarbamate with phenacyl bromides afford the S-alkylation products as a mixture of E/Z-isomers, which undergo cycliza- tion to 5-(2-oxo-4-arylthiazol-3-yl)-1H-imidazole-4-carboxamides under the action of a base. Key words: imidazolyldithiocarbamates, alkylation, intramolecular heterocyclization, 5-(2-oxo-4-arylthiazol-3-yl)-1H-imidazole-4-carboxamides. Earlier, we have shown that 5-aminoimidazole amides 1a,b afford S-ethyldithiocarbamates 3a,b in high yields upon sequential treatment with carbon disulfide and ethyl iodide without isolation of the intermediate imidazolyl-5- dithiocarbamic acid salt 2 (Scheme 1). The latter trans- form easily into the corresponding thioureas under the action of amines and results in imidazo[1,5-c][1,3,5]- thiadiazines in the reactions with dimethyl acetylenedi- carboxylate. 1,2 Scheme 1 R 1 = H (a), Me (b) It is known that the reaction of 5-amino-4-imid- azole(pyrazole)carboxamides with carbon disulfide results in the mercaptopurine 3 and pyrazolopyrimidine deriva- tives, 4 respectively, or pyrazolyldithiocarbamic acids, which undergo subsequently heterocyclization without their isolation. 5 The present work is aimed at the synthesis and study of the reactions of 1H-imidazol-4-yldithiocarbamate 2a and esters 3a,b with phenacyl bromides. Results and Discussion Performing the reaction of 5-aminoimidazoles 1a,b with carbon disulfide under mild conditions allowed isola- tion of triethylammonium 5-carbamoyl-1H-imidazol-4- yldithiocarbamate (2a) in a high yield (see Scheme 1), whose alkylation with ethyl iodide resulted in S-ethyl dithiocarbamate 3a. We synthesized also the analogous methylamide derivative 3b, but without isolation of the intermediate salt of imidazolyldithiocarbamic acid 2b. The presence of several nucleophilic centers in the mol- ecule of substrate 2a contemplates ambiguousness of the reaction pathway with aromatic haloketones. In the reaction of triethylammonium 5-imidazolyl- dithiocarbamate 2a with bromoacetophenones, the for- mation of several products with close chromatographic mobilities was observed, which made impossible the use of chromatography for separation and purification of sub- stances. In attempting to crystallize compounds, they de- composed. The reactions of 5-aminoimidazoles 1a,b with car- bon disulfide and aromatic haloketones as alkylating agents were performed analogously to the reaction with ethyl iodide. However, these reactions resulted in no alkylation products or subsequent cyclization products; after dilu- tion of the reaction mixture with water, the symmetric aromatic disulfides 4a,b (according to the data from 1 H, 13 C NMR, and mass spectrometry and elemental analy- * Dedicated to Academician V. N. Charushin on the occasion of his 60th birthday.