Dehydrohalogenations of cis- and trans-1-bromo-2-flourocyclohexanes

Reactions of both diastereomeric vicinal bromofluorocyclohexanes with sodamide, sodium methoxide, potassium tert-butoxide, and triethylamine were studied. cis-1-Bromo-2-fluorocyclohexane eliminated almost exclusively hydrogen bromide giving mainly 1-fluorocyclohexene and a small amount of 3- fluorocyclohexene. trans-1-Bromo-2-fluorocyclohexane eliminated preferentially hydrogen fluoride on treatment with sodamide. Potassium tert- butoxide eliminated hydrogen bromide and yielded 3-fluorocyclohexene and a small amount of 1,3-cyclohexadiene, whereas sodium methoxide converted trans-1-bromo-2-fluorocyclohexane to 3-fluorocyclohexene and 3-methoxycyclohexene. Possible mechanisms and stereochemistry of the preferential elimination of hydrogen fluoride are discussed and new interpretations are offered.     

The Structures of Uncommon Cationic N‐alkenyl Purine and Pyrimidine Bases

The structures of 1,3 bis‐(allyl)cytosinium bromide ( 1 ), 7,9 bis‐(allyl)adeninium bromide hydrate ( 2 ) and 3‐(butenyl)adeninium bromide ( 3 ) have been determined. 1 is dimeric via N―H…Br hydrogen bonds, which further associate into ribbons via weaker C―H…Br interactions. 2 is also dimeric, now from N―H…N hydrogen bonds, which build up further through a complex array of hydrogen bonds involving both the anion and water of crystallization (O―H…N, O―H…Br, C―H…Br). 3 does not dimerise but forms polymeric sheets via a series of N―H…N, C―H…N and C―H…Br hydrogen bonds.     

Synthesis and molecular and crystal structure of 1-allyl-4-[2-cyano-2-(indan-1,3-dione-2-ylidene)ethylidene] -1, 4-dihydroquinoline

The reaction of 1-allyl-4-methylquinolinium bromide with 2-dicyanomethyleneindan-1,3-dione in the presence of a two-fold excess of triethylamine affords 1-allyl-4-[2-cyano-2-(indan-1,3-dione-2-ylidene) ethylidene]-1,4-dihydrogtiinoline, a representative of a new class of merocyanines. The structure of this compound has been established by X-ray structural analysis. A substantial intramolecular charge transfer and a hydrogen bond between the vinyl hydrogen atom and the indandione oxygen atom have been found.Dedeased in 1995Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 173–176, January, 1996.     

Efficient Procedures for 1-Bromo-1,3-Butadiene and 2-Bromo-1,3-Butadiene

Mixtures of Z- and E-1-bromo-1,3-butadiene in which the E- or Z- isomer predominates have been obtained in good yields by treating a mixture of Z- and E- 1,4-dibromo-2-butene (90% Z-isomer) or pure E-1,4-dibromo-2-butene, respectively, with powdered potassium hydroxide in high-boiling petroleum. 2-Bromo-1,3-butadiene was obtained in high yields by stirring a mixture of vinylacetylene, concentrated aqueous hydrogen bromide and copper(I) bromide.     

Dibenzylimidazolium halides: from complex molecular network in solid state to simple dimer in solution and in gas phase

1,3-Dibenzylimidazolium bromide has been synthesized and the nature of the interactions between cations and anions has been studied in the solid state, in solution and in the gas phase. The cohesion of the crystal is ensured by a combination of hydrogen bonds, and aromatic stacking interactions. In solution and in the gas phase, the supramolecular structural organization due to T-stacking is maintained to a great extent.     

1,4-Benzodiazepines and their derivatives

A series of compounds of the merocyanine dye type was obtained by the reaction of 1-acetyl-1,3-dihydro-2H-1,4-benzodiazepin-2-ones and 1,3-dihydro-2H-1,4-benzodiazepine-2-thiones with 2-methylmercapto-3-ethylbenzothiazolium tosylate, 2-methylmercapto-3,4,5-trimethylthiazolium bromide, 2-methylmercapto-3-methyl-5-phenyloxazolium methosulfate, and 1,3,3-trimethyl-2-formylmethyleneindoline. The hydrogen atoms of the methylene group of the 1-unsubstituted and 1-alkyl-substituted 1,3-dihydro-2H-1,4-benzodiazepin-2-ones are of low mobility, and the indicated compounds do not undergo condensation reactions with electrophilic agents.See [6] for communication VI.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 992–994, July, 1971.     

A mild and environmentally acceptable synthetic protocol for chemoselective α-bromination of β-keto esters and 1,3-diketones

A wide variety of unsubstituted β-keto esters can be brominated chemoselectively to the corresponding α-monobromo-β-keto esters by using a combination of vanadium pentoxide, hydrogen peroxide and ammonium bromide in a biphasic system, dichloromethane-water at 0-5 °C. In addition, α-mono substituted β-keto esters, cyclic β-keto-esters and 1,3-diketones can also be brominated selectively using the same protocol.     

Pincer Receptors for Anions Based on Triazolyl Bile Acids

Copper-catalyzed 1,3-dipolar cycloaddition of azides to acetylenes successfully afforded pincer bistriazolium receptor containing two lithocholic acid fragments and phenylphosphonic diamide bridge. The obtained receptor showed high complexing power toward fluoride ions and organic acid anions, which decreased in the series fluoride > succinate ≥ malonate > oxalate ≥ lithocholate > benzoate > acetate > hydrogen sulfate > bromide.     

Enhanced Reactivity of Chelating Ortho Esters and Dithio-Ortho Esters Towards Grignard Reagents

2-Alkoxy-1,3-dithianes, 2-alkoxy-1,3-benzdithioles and bis(2-alkoxy-1,3-dioxolanes) react substantially faster with phenylmagnesium bromide and phenylethynylmagnesium bromide when the 2-alkoxy group can act as a chelating system for magnesium(II).     

Interaction of benzimidazole-2-thione with propargyl bromide and 1,3-dibromopropyne

Interaction of benzimidazole-2-thione with propargyl bromide under found conditions permitted the direct synthesis of 2-(2-propynylsulfanyl)-3H-1,3-benzimidazolium bromide, the base 2-(2-propynylsulfanyl)-1H-1,3-benzimidazole, stable crystalline 2-(1,2-propadienylsulfanyl)-1H-1,3-benzimidazole, and 3-methyl[1,3]thiazolo[3,2-a][1,3]benzimidazole. The reaction of benzimidazole-2-thione with 1,3-dibromopropyne in chloroform or absolute methanol gave 2-(3-bromo-2-propynylsulfanyl)-3H-1,3-benzimidazolium bromide, and in absolute methanole in the presence of a twofold excess of sodium methoxide the reaction proceeded stereo-and regioselectively to give 3-[(Z)-bromomethylidene][1,3]thiazolo[3,2-a][1,3]benzimidazole. Presented to Academician B. A. Trofimov on his 70^th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, 1399–1405, September, 2008.     

Carbon−Fluorine Bond Formation via a Five-Coordinate Fluoro Complex of Ruthenium(II), Preliminary Communication

The 16-electron, five-coordinate fluoro complex [RuF(dppp)₂]PF₆ ( 1a ; dppp=propane-1,3-diylbis[diphenylphosphine] smoothly reacts with 1,3-diphenylallyl bromide (=1,1′-(3-bromoprop-1-ene-1,3-diyl)bis[benzene]) in dry CDCl₃ to give 1,3-diphenylallyl fluoride and [RuBr(dppp)₂]⁺ in nearly quantitative yield. Under similar conditions, bromide (or chloride)/fluoride exchange also occurs with chlorotriphenylmethane, bromodiphenylmethane, and tert-butyl bromide. The crystal structure of 1a is reported.     

Adamantylation of Imidazoles and Benzimidazole

For the first time is reported on substitution of a hydrogen atom in position 4 of the imidazole ring with an aliphatic substituent occurring in reaction between 1-bromoadamantane and imidazoles. The reaction proceeds alongside the substitution in position 1 at heating in excess imidazole. In o-dichlorobenzene solution adamantylation of benzimidazole afforded 1-(1-adamantyl)benzimidazole and 1,3-di(1-adamantyl)benzimidazolium bromide. The specific features of the reactions course are described. The structure of compounds obtained is proved by ¹H NMR spectroscopy.     

两亲性四硫富瓦烯衍生物的合成及其性质研究

二-(1,3-二硫环戊烯-2-硫酮-4,5-二硫)合锌酸四乙基铵盐(Zincate盐)分别与溴代十四烷和溴代十八烷在乙腈中回流,合成相应的1,3-二硫环戊烯-2-硫酮2a和2b.以亚磷酸三乙酯为偶联剂,其分别和4,5-二氰基乙硫基-1,3-二硫环戊烯-2-酮(3)发生交叉偶合反应合成四硫富瓦烯(TTF)衍生物4a和4b.在氢氧化铯的存在下,4a和4b分别与2-碘乙氧基乙醇反应生成含羟基的四硫富瓦烯(TTF)衍生物5a和5b.以三乙胺为缚酸剂,其与对甲基苯磺酰氯反应,生成含活化羟基的TTF衍生物6a和6b.在氢氧化钠的存在下,6a和6b分别与巯基噻二唑反应生成含有疏水长链烷烃和亲水醚键连接的噻二唑两亲性TTF衍生物7a～7d,并对其进行了1H NMR,13C NMR,IR,MS的表征以及初步电化学行为和Langrnuir-Blodgett膜性能研究.     

HIV-1 RT抑制剂研究I.1,3-二苄基-6-(3,4-环氧丁基)尿嘧啶的合成

报道了1,3-二苄基-6-(3,4-环氧丁基)尿嘧啶的合成新方法.以6-甲基尿嘧啶(1)为起始物,经1,3-二苄基-6-甲基尿嘧啶(2)及未见文献报道的1,3-二苄基-6-(3-丁烯基)尿嘧啶(3)和1,3-二苄基-6-(3-羟基-4-溴丁基)尿嘧啶(4),首次高收率合成了1,3-二苄基-6-(3,4-环氧丁基)尿嘧啶(5),并对其化学结构进行了表征.     

Zirconium-mediated cross-coupling of terminal alkynes and vinyl bromides: selective synthesis of cyclobutene and 1,3-diene derivatives

A diastereoselective synthesis of 1,3-butadiene or cyclobutene derivatives by a zirconium-mediated reaction of alkenyllithium compounds and vinyl bromides is reported. The key steps involve the generation of zirconocene-alkyne complexes from haloalkenes and subsequent coupling with alkenyl bromides. Thus, formally the process supposes the cross-coupling reaction between a terminal alkyne and an alkenyl bromide. Moreover, the use of butyl vinyl ether instead of vinyl bromide as the unsaturated system allows an alternative access to different 1,3-butadiene regioisomers.     

Condensed 1,3-benzothiazinones. 1. Facile synthesis of 2-amino-1,2,4-triazolo[5,1-b][1,3]-benzothiazin-9-one

Treating 2-mercaptobenzohydrazide ( 1a ) with cyanogen bromide gave 3-amino-2-imino-3,4-dihydro-2.H-1,3-benzothiazin-4-one ( 2a ). This compound underwent further cyclocondensation with a second molecule of cyanogen bromide or S-methylisothiourea sulfate to afford the biologically interesting 2-amino-1,2,4-triazolo-[5,1-b][1,3]benzothiazin-9-one ( 3c ). Compound 3c could also be prepared directly from 1a by treating with excess amount of cyanogen bromide in more satisfactory yield.     

5-叔丁基-5-(1'-羟基-2'-甲基丙基)-2,2-二甲基-1,3-二氧六环的合成研究

为得到3,4-二取代双环硫化磷酸酯的中间体5-叔丁基-5-(1'-羟基-2'-甲基丙基)-2,2-二甲基-1,3-二氧六环, 通过5-叔丁基-5-甲酰基-2,2-二甲基-1,3-二氧六环与异丙基溴化镁反应没有得到目标化合物, 而得到了还原产物, 改用异丙基锂代替异丙基溴化镁反应后得到目标化合物, 通过超声波辅助反应, 大幅度提高了反应收率.     

Synthesis and reactions of (E)- and (Z)-1,3-dibromo-2-methoxypropene

(Z)-1,3-Dibromo-2-methoxypropene is prepared in 90% yield by dehydrohalogenation of 1,2,3-tribromo-2-methoxypropane with diisopropylamine in dichloromethane. The E-isomer can be obtained as the only product in almost quantitative yield by UV irradiation of the Z-isomer. Nucleophilic displacement reactions of the allylic bromide and palladium-catalyzed coupling reactions of the vinylic bromide in (E)- and (Z)-1,3-dibromo-2-methoxypropene have been studied.     

Hydrolysis of 6,6-dimethyl-4,8-dioxo-5,7-dioxaspiro[2.5]octane-1,1,2,2-tetracarbonitrile

Hydrolysis of 6,6-dimethyl-4,8-dioxo-5,7-dioxaspiro[2.5]octane-1,1,2,2-tetracarbonitrile in aqueous dioxane in the presence of hydrogen bromide gave a mixture of 2,2,3,3-tetracyanocyclopropane-1-carboxylic acid and ammonium 3-cyano-4-dicyanomethylidene-5-oxo-4,5-dihydro-1H-pyrrol-2-olate. Hydrolysis of the same compound in the presence of sulfuric acid was accompanied by nitrogen migration and led to the formation of (1R*,2S*,3S*)-1,3-dicyanocyclopropane-1,2-dicarboxamide whose structure was proved by X-ray analysis.     

Determination of low concentrations of hydrogen halides and halogens in the gas phase: removal from a mixture of gases and quantitative estimation

A method has been developed for the removal of hydrogen chloride, and mixtures of bromine and hydrogen bromide, from gaseous mixtures by absorption on various solids. The efficiency of removal of bromine and hydrogen bromide has been determined and the substances have been estimated potentiometrically. The technique is extended to include the other halogens and hydrogen halides.