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The appropriate 1-arylhydrazinecarbonitriles 1a&ndash, c are subjected to the reaction with 2-chloro-4,5-dihydro-1H-imidazole (2), yielding 7-(4,5-dihydro-1H-imidazol-2-yl)-2-aryl-6,7-dihydro-2H-imidazo[2,1-c][1,2,4]triazol-3(5H)-imines 3a&ndash, c, which are subsequently converted into the corresponding amides 4a&ndash, e, 8a&ndash, c, sulfonamides 5a&ndash, n, 9, ureas 6a&ndash, I, and thioureas 7a&ndash, d. The structures of the newly prepared derivatives 3a&ndash, c, 4a&ndash, e, 5a&ndash, n, 6a&ndash, i, 7a&ndash, d, 8a&ndash, c, and 9 are confirmed by IR, NMR spectroscopic data, as well as single-crystal X-ray analyses of 5e and 8c. The in vitro cytotoxic potency of these compounds is determined on a panel of human cancer cell lines, and the relationships between structure and antitumor activity are discussed. The most active 4-chloro-N-(2-(4-chlorophenyl)-7-(4,5-dihydro-1H-imidazol-2-yl)-6,7-dihydro-2H-imidazo[2,1-c][1,2,4]triazol-3(5H)-ylidene)benzamide (4e) and N-(7-(4,5-dihydro-1H-imidazol-2-yl)-2-(p-tolyl)-6,7-dihydro-2H-imidazo[2,1-c][1,2,4]triazol-3(5H)-ylidene)-[1,1&prime, biphenyl]-4-sulfonamide (5l) inhibits the growth of the cervical cancer SISO and bladder cancer RT-112 cell lines with IC50 values in the range of 2.38&ndash, 3.77 &mu, M. Moreover, N-(7-(4,5-dihydro-1H-imidazol-2-yl)-2-phenyl-6,7-dihydro-2H-imidazo[2,1-c][1,2,4]triazol-3(5H)-ylidene)-4-phenoxybenzenesulfonamide (5m) has the best selectivity towards the SISO cell line and induces apoptosis in this cell line.

The reaction of bidentate 1-(pyridin-2-yl)-2,3,7,8-tetrahydro-1H-imidazo[2,1-b][1,3,5]triazepin-5(6H)-one ligands (3a–g) with copper(II) chloride, carried out at ambient temperature in aqueous EtOH or DMF, led to the formation of corresponding complexes 4 of type [Cu(L)(Cl)2], which in the presence of water and excess of Cu2+ ions provided copper(II) complexes (5) of tridentate N1-[1-(pyridin-2-yl)imidazolidin-2-ylidene]ethane-1,2-diamine ligands of the formula {[Cu(L)(μ-Cl)]2Cl2}n. Structures of the selected complexes 4 and 5 were confirmed by single crystal X-ray crystallography. The mechanism of the observed copper(II)-assisted hydrolysis of cyclic ureas 3 was elucidated with the aid of quantum chemical calculations.

We have used isoxazolo[3,4-b]pyridin-3(1H)-one and isoxazolo[3,4-b]quinolin-3(1H)-one as "masked" heterocyclic hydroxylamines to generate Paal-Knorr intermediates of the Trofimov pyrrole synthesis. The previously inaccessible intermediates, trapped by ethyl propiolate, were obtained by reacting corresponding isoxazolones with 4-fold excess of ethyl propiolate under basic conditions at ambient temperature, and characterized by means of IR and NMR spectroscopic data as well as by single crystal X-ray analysis. Quantum chemical calculations of a [3,3]sigmatropic rearrangement of the N,O-divinyl hydroxylamines to corresponding imino-aldehydes (Paal-Knorr intermediates) revealed that this reaction proceeds via chairlike transition state and is exothermic.

The pyrithione derivative, bis{2-[(1-oxidopyridin-2-yl)sulfanyl]-4,5-dihydro-1H-imidazol-3-ium} tetrachlorocuprate(2-) (1a) has been obtained by the reaction of one equivalent of 2-[(4,5-dihydro-1H-imidazol-2-yl)thio]pyridine 1-oxide hydrochloride with one and a half equivalents of copper (II) chloride dihydrate in methanol in a very good yield. The structure of this product was confirmed by X-ray crystallography, infrared spectroscopy, and elemental analysis.

The guanidine derivative N-{[(7-(4,5-dihydro-1H-imidazol-2-yl)-2-(p-tolyl)-6,7-dihydro-2H-imidazo[2,1-c][1,2,4]triazol-3(5H)-ylidene)amino](phenylamino)methylene}benzamide (3) has been obtained by the reaction of one measure of N-{[7-(4,5-dihydro-1H-imidazol-2-yl)-2-(p-tolyl)-6,7-dihydro-2H-imidazo[2,1-c][1,2,4]triazol-3(5H)-ylidene]carbamothioyl}benzamide (2) with one measure of aniline in the presence of mercury(II) chloride and triethylamine in anhydrous dimethylformamide. The structure of product 3 was confirmed by 1H and 13C-NMR, infrared spectroscopy, and elemental analysis.

A series of 2-imino-2H-chromen-3-yl-1,3,5-triazine compounds 5&ndash, 12, which are namely hybrids of 2,4-diamino-1,3,5-triazines and 2-imino-coumarins, was synthesized by reacting 2-(4,6-diamine-1,3,5-triazin-2-yl)acetonitriles 1&ndash, 4 with 2-hydroxybenzaldehydes. After this, upon heating in aqueous DMF, 2-imino-2H-chromen-3-yl-1,3,5-triazines 10 and 12 were converted into the corresponding 2H-chromen-3-yl-1,3,5-triazines 13 and 14, which are essentially hybrids of 2,4-diamino-1,3,5-triazines and coumarins. The in vitro anticancer activity of the newly prepared compounds was evaluated against five human cancer cell lines: DAN-G, A-427, LCLC-103H, SISO and RT-4. The greatest cytotoxic activity displayed 4-[7-(diethylamino)-2-imino-2H-chromen-3-yl]-6-(4-phenylpiperazin-1-yl)-1,3,5-triazin-2-amine (11, IC50 in the range of 1.51&ndash, 2.60 &mu, M).