SYNTHESIS OF 2-[(5-ARYL-2-FURYL)METHYLENE]-5,6-DIPHENYLIMIDAZO[2,1-B][1,3]THIAZOL-3-ONES

Condensed five-membered nitrogen- and sulfur-containing heterocycles continues to attract the attention of synthetic chemists with high reactivity and a variety of chemical transformations. Due to a wide range of biological activity azole derivatives are proposed for use in modern medicine and biotechnology. It is known that compounds which contains imidazole fragment are part of a number of drugs such as: naphthizine, dibasole, metronidazole. 5-Arylfuran derivatives also have the broad spectrum of biological activity. Convenient method for preparation of arylfuran compounds is a catalytic arylation of furan derivatives with arenediazonium salts under the conditions of Meerwein reaction. In this work the initial 5-arylfuran-2-carbaldehyde were obtained by furan-2-carbaldehyde arylation in the presence of CuCl2 as a catalyst. These aldehydes can be involved in three-component reaction with derivatives of azoles which were described above. Tandem and domino reactions, as well as multicomponent reactions, are increasingly used in the practice of organic synthesis. Multicomponent reactions make possible to synthesize target compounds with greater efficiency, atom economy and contribute to the introduction of the concept of "green" chemistry. We investigated the interaction of 5-aryl-2-furancarbaldehydes with chloroacetic acid and 4,5-diphenyl-1,3-dihydro-2H-imidazole-2-thione. Experiments have shown that this reaction occurs when the reagents are heated in glacial acetic acid and in the presence of fused sodium acetate. In these conditions, chloroacetic acid is cyclized with 4,5-diphenyl-1,3-dihydro-2H-imidazole-2-thione. Under the same conditions, the active methylene group of the thiazolidinone ring formed reacts with aldehydes. As a result 2-[(5-aryl-2-furyl)methylene]-5,6-diphenylimidazo[2,1-b][1,3]thiazol-3-ones are formed. Thus, a synthetic way is proposed for the construction of hybrid structures in which the imidazo [2,1-b][1,3]thiazole fragment is coupled with arylfuran, which makes them perspective objects for screening for biological activity.