Natalia V. Obruchnikova

One-pot synthesis of 5-phenylimino, 5-thieno or 5-oxo-1,2,3-dithiazoles and evaluation of their antimicrobial and antitumor activity

We here report the synthesis and biological evaluation of rare 4-substituted-5-phenylimino, 5-thieno- and 5-oxo-1,2,3-dithiazoles. Dithiazoles were selectively obtained in moderate to high yields (25-73%) via a one-pot reaction from various ethanoneoximes with sulfur monochloride, pyridine in acetonitrile followed by treatment by corresponding nucleophiles (aniline, thioacetamide and formic acid). All the synthesized compounds were screened for their antibacterial (against bacteria Escherichia coli, Salmonellaenterica serovar Typhimurium, Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus, Enterococcus faecalis, Bacillus cereus and Listeria inocua), antifungal (against pathogenic strains Candida albicans, Candida glabrata, Candida tropicalis and Issatchenkia orientalis) and antitumor (on human cell lines MCF-7 and MDA-MB-231) activity. 4-(2-Pyridinyl)-5H-1,2,3-dithiazole-5-thione and 4-ethylcarboxyl-5H-1,2,3-dithiazole-5-thione (5d, 5h) that are active against Gram-positive bacteria are significantly active against fungi. 4-(2-Benzofuranyl)-5-phenylimino-5H-1,2,3-dithiazole (4e) exerts antiproliferative activity.

A MILD CONVENIENT SYNTHESIS OF HETEROCYCLIC TRIPHENYLPHOSPHINE IMINES

Abstract A series of heterocyclic phosphine imines (1,3,5-triazines, pyrazines, pyridines, furazans and furoxans) have been readily prepared by direct action of N-trimethylsilyl-P,P,P-triphenylphosphine imines on chloro-or nitroderivatives.

Syntheses with nitrile oxides. 2. Reaction of aromatic nitrile oxides with bis(trimethylsilylcarbodiimide)

The reaction of aromatic nitrile oxides with bis(trimethylsilylcarbodiimide) gives 5-amino-3-aryl-1,2,4-oxadiazoles.

Syntheses based on nitrile oxides. 1. Reaction of aromatic nitrile oxides with N-cyanimides

The reaction of trialkylaminocyanimides with aromatic nitrile oxides leads to trialkylamino-(3-aryl-1,2,4-oxadiazol-5-yl)imides, while the corresponding reactions with sulfylcyanimines and phosphincyanimides do not take place. Using x-ray structural analysis the principal structural features of the 1,2,4-oxadiazole products have been elucidated.

Synthesis of 4,8-dihydro-7H-[1,2]dithiolo[3,4-b][1,2,5]oxadiazolo-[3,4-e]pyrazine-7-thione as a new heterocyclic system

Sulfur monochloride and its complexes with tertiary amines are important sources of sulfur in the synthesis of novel heterocyclic systems.1—4 This available and inex pensive reagent allows such transformations to be com pleted in one step.5 With 3,4 diaminofurazan and 4 ami no 3 nitrofurazan as examples, we have discovered an ear lier unknown transformation of the 1,2,5 oxadiazole ring into the 1,2,5 thiadiazole ring under the action of sulfur monochloride.6,7 By analyzing the results obtained, we concluded that the furazan ring should contain an NH substituent for this transformation to be successful. For a further study of reactions of 1,2,5 oxadiazoles with sulfur mono chloride, we used 3,4 bis(alkyl amino)furazans 1 (R = Et, Pri) as new starting materials. Earlier, we have found that the N ethyl8 and N isopropyl9 groups can also interact with S2Cl2, so the reaction pathway for com pounds 1 was unpredictable. It turned out that 3,4 bis(alkylamino)furazans 1 (R = Et (a), Pri (b)) both react with S2Cl2 in hot dimethyl formamide (100—105 C) over 2 h. The reaction with bis(ethylamino) derivative 1a gave an inseparable mixture of products, from which we failed to isolate individual compounds. The reaction with 3,4 bis(isopropylamino) furazan 1b yielded a product containing only one isopro pyl group (NMR data). Data from elemental analysis, 1H and 13C NMR spectroscopy, IR spectroscopy, and mass spectrometry suggest two possible tricyclic structures for this product: oxadiazolodithiolopyrazinethione 2 or thia diazolodithiolopyrazinone 3 (Scheme 1). X ray diffraction provided conclusive evidence for structure 2 (Fig. 1, Table 1). The formation of product 2 can be explained by a trans formation9,10 of the N isopropyl group of furazan 1b into R = Et (a), Pri (b)

Syntheses based on nitrile oxides

Interaction of aromatic nitrile oxides with bis-trimethylsilylthiodiimide results in 2-amino-4-aryl-1,2,3,5-oxathiadiazoles, the first representatives of a new class of heterocyclic compounds.