N. O. Yarosh

Alkylation of imidazole and benzimidazole derivatives with 1-(iodomethyl)-1,1,3,3,3-pentamethyldisiloxane – a new method for the preparation of organocyclosiloxane iodides

The reaction of imidazole and benzimidazole derivatives with 1-(iodomethyl)-1,1,3,3,3-pentamethyldisiloxane resulted in N1,3-alkylation, cleavage of siloxane bonds by the evolved hydrogen iodide, and the formation of cyclic organosilicon iodides and triiodides.

Alkylation of 2-methylimidazole with iodomethyl ketones of the aliphatic, aromatic, and heteroaromatic series

A classical procedure for the synthesis of N-alkylimidazoles is based on the reaction of imidazole with alkyl halides under pressure at 100–150°C [8]. Reactions of imidazoles with alkyl halides, α-bromo(chloro) ketones, and chloroalkyl formates in the presence of bases or phase-transfer catalysts give both N-mono[2, 3, 9] and N,N-dialkylation products [10]. Alkylation of imidazole derivatives with α-iodo ketones in the absence of a base and catalyst has not been reported so far. There are grounds to believe that α-iodo ketones can be successfully used in the synthesis of diazolyl ketones in one preparative step due to high reactivity of the C–I bond therein. For this purpose, we examined the reactions of 2-methyl-1H-imidazole (I) with 1-iodopropan-2-one (IIa), 1-(biphenyl-4-yl)-2-iodoethanone (IIb), and 2-iodo-1-(2-thienyl)ethanone (IIc) in acetone at 40°C. These reactions led to the formation of mixtures of 2-methyl-1,3-bis(2-oxopropyl)-3H-imidazol-1-ium, 1,3-bis[2-(biphenyl-4-yl)-2-oxoethyl]-2-methyl-3Himidazol-1-ium, and 2-methyl-1,3-bis-[2-oxo-2-(2thienyl)ethyl]-3H-imidazol-1-ium iodides IIIa–IIIc with the corresponding triiodides IVa–IVc. The ratio of iodides III and triiodides IV is determined by the ability of iodo ketones IIa–IIc to undergo reduction with hydrogen iodide liberated as a result of first alkylation. Triiodide ion is formed via addition of iodide ion to molecular iodine arising from the reduction of ketones IIa–IIc with hydrogen iodide.

Alkylation of 1,3-bis(benzotriazol-1-yl)propan-2-one with α-iodo ketones

Functionalized bis-azoles can be obtained by alkylation. However, published data on such reactions are few in number, presumably because of low reactivity of bis-azoles toward conventional alkylating agents. It is only known that the alkylation of bis(benzotriazolyl)arenes with bis(bromomethyl)arenes leads to the corresponding cyclophanes in 30–50% yield [5]. Alkylation of 1,3-bis(benzotriazol-1-yl)propan-2-one with α-iodo ketones was not described.

Synthesis of the first organylcyclosiloxane containing a benzimidazole fragment in the cycle

Cyclosiloxanes are monomers for the preparation of corrosion-resistant sealants, lubricants, hydraulic fluids, and rubbers operating over a wide temperature range [1, 2]. Main procedures for the synthesis of cyclosiloxane derivatives are based on catalytic rearrangement of polysiloxanes [3], cyclooligomerization of acetoxysilanes [4], and hydrolytic polycondensation of fluoropropylmethyl[5], polyfluorocyclobutyl[6], methylphenyl[7], and hydrogen-containing dichlorosilanes [8] with subsequent thermocatalytic treatment of the hydrolysis products. We now propose a new one-step procedure for the preparation of organylcyclosiloxane III via reaction of benzimidazole (I) with 1,3-bis(iodomethyl)-1,1,3,3tetramethyldisiloxane (II). The reaction was carried out in melt (190°C, 1 h) and is likely to involve N,N-alkylation of diazole I with disiloxane II through insertion of intermediate silanones into intermediate A molecule. In keeping with the α-elimination concept [9–11], the formation of silanone may be expected to result from coordination of the oxygen atom in siloxane II to proton of hydrogen iodide and subsequent decomposition of the complex thus formed. The structure of cyclosiloxane III was proved by elemental analyses and IR, H, C, N, and Si NMR, and mass spectra. The H and C NMR spectra of ISSN 1070-4280, Russian Journal of Organic Chemistry, 2014, Vol. 50, No. 9, pp. 1377–1379.

The synthesis of the first acetylenic silyl derivatives of 2-methylimidazole and benzimidazole

The earlier unknown acetylenic silyl iodides of linear and cyclic structure form in the reaction of 2-methylimidazole and benzimidazole with bis[dimethyl(iodomethyl)silyl]ethyne. The synthesized compounds are characterized by the data of elemental analysis, 1Н, 13С, 15N, 29Si NMR, IR, Raman and UV spectroscopy.

Synthesis of the First Siloxane Derivatives of Triazoles

We studied the interaction of triazole and its derivatives with 1,3-bis(iodomethyl)-1,1,3,3-tetra-methyldisiloxane, resulting in a mixture of organyl cyclosiloxanes and ionic liquids in a ratio depending on the properties of the base used as starting material.

Synthesis of first heterocyclic disulfonium dications from 1,3-benzothiazole-2-thiol and 1-iodopropan-2-one

Derivatives of 1,3-benzothiazole-2-thiol (1, 2-mercaptobenzothiazole, Captax) constitute an important class of organic compounds which exhibit biological activity and are used in industry. They possess antibacterial, antifungal, antitumor, antispasmodic, antiinflammatory, antioxidant, and antiallergic activity and accelerate vulcanization of rubber [1–4]. Obviously, studies of these compounds could reveal their unexpected properties and new potential applications.

New approach to the synthesis of imidazolophanes

Development of selective procedures for building up imidazolophanes possessing an inner cavity is very promising from the viewpoint of the design of specific receptors and sensors [1], molecular containers [2], catalysts [3], ionic liquids [4], and medical agents exhibiting antibiotic and antitumor properties [5]. Up to now, two-step methods for the preparation of imidazolophanes have been reported; these methods are based on intermolecular quaternization of bisimidazoles {obtained by reaction of imidazole with bis[chloro(bromo)methyl]-substituted aliphatic and aromatic compounds in the presence of NaH or NaOH} with various dihalo derivatives [4–7]. We now propose a one-step synthesis of imidazolophanes via alkylation of 2-methylimidazole (I) with 1,3-diiodopropan-2-one (II). The reaction was carried out under mild conditions (20–25°C, 3 h) in the absence of a catalyst. According to the H, C, and N NMR data, the first step was quaternization of the more nucleophilic N atom in I [8] with diiodoketone II, and next followed N-autoalkylation of intermediate imidazolium salt A. The structure of the first representative of imidazolophanes with 2-oxotrimethylene spacers was proved by elemental analysis and IR, H, C, and N NMR, and mass spectra. The H and C NMR spectra of III lacked signals assignable to terminal iodomethyl group. In the two-dimensional N NMR spectrum of III we observed a cross peak due to interaction between methylene protons and equivalent nitrogen atoms in the imidazole rings. These findings indicated symmetrical cyclic structure of molecule III. The described reaction provides a novel approach to the synthesis of imidazolophanes, which opens new prospects in the design of cyclophanes with various spacers. The mechanism of this reaction and its scope will be the subjects of our further studies. Imidazolophane (III). A solution of 1.24 g (4 mmol) of 1,3-diiodopropan-2-one (II) in 2 ml of acetone was added dropwise under stirring in an argon atmosphere to a solution of 0.33 g (4 mmol) of 2-methyl-1H-imidazole (I) in 3 ml of acetone. The mixture was stirred for 3 h, and the precipitate was filtered off, washed with acetone and diethyl ether, and dried under reduced pressure. Yield 0.65 g (62%), yellow powder, mp 198–200°C. IR spectrum, ν, cm: 1748 (C=O), 2912, 1418 (CH2). H NMR spectrum, δ, ppm: 2.53 s (3H, CH3), 5.64 s (4H, CH2), 7.61 s (2H, 4-H, 5-H). C NMR spectrum, δC, ppm: 9.97 (CH3), 54.95 (CH2), 122.47 (C, C), 147.16 (C), 194.33 (C=O). N NMR spectrum: δN –211.9 ppm. Mass spectrum: m/z 537 [M – HI – I]. Found, %: C 31.52; H 3.71; I 47.02; N 10.57. C21H27I3N6O3. Calculated, %: C 31.84; H 3.44; I 48.06; N 10.60. ISSN 1070-4280, Russian Journal of Organic Chemistry, 2013, Vol. 49, No. 10, pp. 1546–1547.

Alkylation of C- and N-aminotriazoles with α-iodoketones

C- and N-Amino-1,2,4-triazoles react with 1-iodopropan-2-one in the absence of bases and phasetransfer catalysts (40°C, 9-12 h) to furnish 3-amino-1,4-bis(2-oxo-propyl)-4H-1,2,4-triazolium triiodide and 4-amino-1-(2-oxopropyl)-4H-1,2,4-triazolium iodide. The alkylation of 1,2,4-triazol-4-amine with 1-iodopropan-2-one and 1,3-diiodopropan-2-one in the presence of elemental iodine led to the formation of 4-amino-1-(2-oxopropyl)-4H-1,2,4-triazolium triiodide and 2-oxopropane-1,3-diylbis(4-amino-4H-1,2,4-triazolium) bis(triiodide). Triiodides are oily fluids possessing electric conductivity of 1.1 × 10−3 Ω m−1 opening the route to new types of electroconducting ionic liquids.

S- and N-alkylation of 2,2′-(alkane-α,ω-diyldisulfanediyl)-bis(1,3-benzothiazoles) with 1-iodopropan-2-one in the presence of iodine

The alkylation of 2,2′-(methylenedisulfanediyl)- and 2,2′-(ethane-1,2-diyldisulfanediyl)bis-(1,3-benzothiazoles) with 1-iodopropan-2-one involves exclusively the exocyclic sulfur atoms. The presence of an electron-withdrawing carbonyl group between the bridging methylene units in 1,3-bis(1,3-benzothiazol-2-ylsulfanyl)propane-2-one forces the alkylation to occur at the endocyclic nitrogen atoms.