Voltammetric study of interfacial electron transfer between bis(cyclopentadienyl)iron in organic solvents and hexacyanoferrate in water.

The electron-transfer reaction between bis(cyclopentadienyl)iron(II) ([Fe(II)(C5H5)2]) in nitrobenzene and a hexacyanoferrate redox couple ([Fe(II/III)(CN)6](4-/3-)) in water at the nitrobenzene / water interface was studied using normal pulse voltammetry. The voltammetric results indicate that the electron-transfer reaction takes place by way of a so-called ion-transfer (IT) mechanism, of which the forward and backward rate constants of the homogeneous electron-transfer reaction between [Fe(II/III)(C5H5)2](0/+) and [Fe(II/III)(CN)6](4-/3-) in the water phase have been determined. The electron-transfer reaction between [Fe(II)(C5H5)2] in 1,2-dichloroethane and [Fe(II/III)(CN)6](4-/3-) in water at the 1,2-dichloroethane / water interface was shown to also take place by the IT-mechanism.     

Generation of arylnitrenium ions by nitro-reduction and gas-phase synthesis of <Emphasis Type="Italic">N</Emphasis>-Heterocycles

Nitro-reduction by the vinyl halide radical cation CH2 = CH-X+* (X = Cl or Br) converts nitroaromatics into arylnitrenium ions, significant intermediates in carcinogenesis, and the present study reports on the scope and regioselectivity of this versatile reaction. The reaction is general for different kinds of substituted nitroaromatics; para/meta substitutents have little effect on the reaction while ortho substitutents result in low yields of arylnitrenium ions. The phenylnitrenium ion PhNH+ can be generated by chemical ionization (CI) of nitrobenzene using 1,2-dichloroethane as the reagent gas or by atmospheric pressure chemical ionization (APCI) of 1,2-dichloroethane solution doped with nitrobenzene. The chemical reactivities of the arylnitrenium ions include one-step ion/molecule reactions with nucleophiles ethyl vinyl ether and 1,3-dioxolanes, respectively, involving the direct formation of new CN bonds and synthesis of indole and benzomorpholine derivatives. The indole formation reaction parallels known condensed phase chemistry, while the concise morpholine-forming reaction remains to be sought in solution. The combination of collision-induced dissociation (CID) with novel ion/molecule reactions should provide a selective method for the detection of explosives such as TNT, RDX and HMX in mixtures using mass spectrometry. In addition to the reduction of the nitro group, reduction of methyl phenyl sulfone PhS(O)2Me to the thioanisole radical cation PhSMe+* occurs using the same chemical ionization reagent 1,2-dichloroethane. This probably involves an analogous reduction reaction by the reagent ion CH2 = CH-Cl+*.     

Sustainable Access to Acridin-9-(10H)ones with an Embedded m-Terphenyl Moiety Based on a Three-Component Reaction

A Ce(IV)-catalyzed three-component reaction between chalcones, anilines and β-ketoesters followed by a microwave-assisted thermal cyclization afforded 1,3-diaryl-1,2-dihydroacridin-9(10H)-ones. Their microwave irradiation in nitrobenzene, acting both as solvent and oxidant, afforded fully unsaturated 1,3-diarylacridin-9(10H)-ones, which combine acridin-9-(10H)one and m-terphenyl moieties. Overall, the route generates three C-C and one C-N bond and has the advantage of requiring a single chromatographic separation.     

In‐situ cryocrystallization of 1,2‐dimethyl‐3‐nitrobenzene and 2,4‐dimethyl‐1‐nitrobenzene

The crystal structures of 1,2‐dimethyl‐3‐nitrobenzene, C₈H₉NO₂, and 2,4‐dimethyl‐1‐nitrobenzene, C₈H₉NO₂, which are liquids at room temperature, have been obtained through in‐situ cryocrystallization. Weak C—H...O and also π–π interactions are present in both crystal structures.     

1,2-migration of 2'-oxoalkyl group and concomitant synthesis of 2-C-branched O-, S-glycosides and glycosyl azides via 1,2-cyclopropanated sugars

Treatment of 2'-oxoalkyl 2-O-Ms(Ts)-alpha-C-mannosides (4, 5, and 6) with base resulted in 1,2-cyclopropanation via an intramolecular SN2 reaction due to their 1,2-trans-diaxial configurations. The 1,2-cyclopropanated sugars (10 and 13) were reacted with various alcohols, thiols, and sodium azide to produce 2-C-branched O- and S-glycosides and glycosyl azides (11, 14-28) in good to excellent yields. In contrast, 1,2-cis 2'-oxoalkyl 2-O-Ms(Ts)-alpha-C-glucoside 9 formed an acyclic conjugated aldehyde (31) under basic conditions, which occurred by 1'-enolation followed by beta-elimination. An intramolecular Michael addition from 31 produced 2-O-Ms-beta-C-glucoside 30 as a major product. However, due to the electron-withdrawing effect exerted by 2-O-Ms compound 31 also undergoes a C2 epimerization to form 32. Thereafter, the intramolecular Michael addition led to the formation of both 1,2-trans 2'-oxoalkyl 2-O-Ms-alpha-C-mannoside 4 and its beta-anomer (33). Because beta-elimination/Michael addition and C2 epimerization are reversible reactions, equilibriums among 9, 31, 30, 32, 33, and 4 were established, which included the transformation of 1,2-cis C-glucoside 9 into 1,2-trans C-mannoside 4. The subsequent 1,2-cyclopropanation of 4 was an irreversible reaction yielding 1,2-cyclopropanated 10 and further conversion to 1,2-migration products (11 and 12).     

Synthesis of pyrrolo[1,2-a]quinoxalines by 1,3-dipolar cycloaddition reaction. An additional reaction mechanism via an aziridine intermediate

The reaction of the 2-substituted 6-chloroquinoxaline 4-oxides 1a or 1b with 2-fold molar amount of methyl propiolate resulted in the 1,3-dipolar cycloaddition reaction to give 8-chloro-1,3-bismethoxycarbonyl-4-(piperidin-1-yl)pyrrolo[1,2-a]quinoxaline 4a or 8-chloro-1,3-bismethoxycarbonyl-4-(morpholin-4-yl)pyrrolo-[1,2-a]quinoxaline 4b , respectively. Compound 4a or 4b was transformed into 8-chloro-3-methoxycarbonyl-4-(piperidin-1-yl)pyrrolo[1,2-a]quinoxaline 5a or 8-chloro-3-methoxycarbonyl-4-(morpholin-4-yl)pyrrolo[1,2-a]-quinoxaline 5b , respectively. The structure of 4a,b was confirmed by the NOE measurement among the C₁ -H , C ₂-H and C ₉-H proton signals of 5a,b . An additional reaction mechanism was proposed for the ring transformation of isoxazolo[2,3-a]quinoxalines into pyrrolo[1,2-a]quinoxalines.     

Synthetic strategies to a telomere-targeted pentacyclic heteroaromatic salt

Three routes have been explored to synthesise the telomere-targeted agent 3,11-difluoro-6,8,13-trimethyl-8H-quino[4,3,2-kl]acridinium methosulfate . Application of a 6-(2-azidophenyl)phenanthridine precursor gave an entry to the indazolo[2,3-f]phenanthridine ring system not the required quino[4,3,2-kl]acridine. A six step synthesis starting from 2,6-dibromo-4-methylbenzonitrile via a 1-arylacridin-9(10H)-one intermediate, or , gave the required in low overall yield (<10%). The most efficient route entailed the one-pot (five step) conversion of 1,2-dimethyl-6-fluoroquinolinium methosulfate to in 33% yield employing triethylamine as base and nitrobenzene as solvent.     

Synthesis, reactivity and structural studies of carboranyl thioethers and disulfides

The equimolar reaction of 1-SH-2-R-1,2-closo-C2B10H10(R=Me, H, Ph) with KOH in ethanol produces the thiolate species [1-S-2-R-1,2-closo-C2B10H10]-. These react with iodine to give the disulfide bridged dicluster (1-S-2-R-1,2-closo-C2B10H10)2(R=H, Me, Ph) compounds as analytically pure, white and air-stable solids in high yield. Synthesis of monothioether bridged species is synthetically more difficult. In fact three procedures have been tested to obtain the thioether bridged dicluster compounds (2-R-1,2-closo-C2B10H10)2S (R=Me, H, Ph) but only (2-Me-1,2-closo-C2B10H10)2S was successfully synthesized and characterized. Attempts to produce mixed compounds (1-R-1,2-closo-C2B10H10)S(1-R'-1,2-closo-C2B10H10), R not=R', were unsuccessful. Deboronation reaction of this dicarboranylthioether lead, depending on the reaction conditions, to monoanionic [(2-Me-1,2-closo-C2B10H10)S(8-Me-7,8-nido-C2B9H10)]- or dianionic [(8-Me-7,8-nido-C2B9H10)2S]2- sulfur bridge anions. Deboronation of carboranyl disulfides gave the corresponding dianionic [(7-S-8-R-7,8-nido-C2B9H10)2]2-(R=H, Me, Ph) species. This reaction was very dependent, however, on the reaction conditions. With slight variation of the reaction conditions, splitting of the S-S bond leading to the thiolate species with retention of the closo cluster was also found. Carboranyl disulfides (1-S-2-R-1,2-closo-C2B10H10)2(R=H, Me, Ph) do not lead to thiosulfinates R-S(O)-S-R' by oxidation with H2O2 or I2 as organic disulfides do. This behaviour is attributed to the presence of the sulfur atom directly bonded to the carbon cluster that produces electronic transfer from the filled orbitals on the sulfur atom into the cage LUMO (largely located on the cage Cc-Cc bond). This causes a depletion of electron density on the sulfur, thence impairing sulfur oxidation, and facilitating S-S breaking. Crystal structures of monothioethers (2-Me-1,2-closo-C2B10H10)2S, [NMe4][(2-Me-1,2-closo-C2B10H10)S(8-Me-7,8-nido-C2B9H10)](the first example reported in the literature of a two cluster compound incorporating the closo C2B10 and the nido[C2B9]- moieties linked by a one member spacer) and disulfides (1-S-1,2-closo-C2B10H11)2, (1-S-2-Me-1,2-closo-C2B10H10)2, (1-S-2-Ph-1,2-closo-C2B10H10)2 are reported which support the behaviour of these species.     

Reduction of Nitrobenzene to Aniline with Carbon Monoxide and Water in the Presence of the PdCl2/Fe/I2 System

A study of modified catalyst systems composed of palladium or its chloride and a co-catalyst such as metallic Fe-powder, iodine, and pyridine was used in the reduction of nitrobenzene to aniline with carbon monoxide and water at 180°C and 2.5-4 MPa pressure. The reaction is complete in 2 h with a nitrobenzene conversion of 98-100% and a 100% selectivity with respect to aniline.     

Condensation of 1-Substituted 1,2,3,9a-Tetrahydro-9H-imidazo[1,2-a]indol-2-one Derivatives with Aromatic Aldehydes

Condensation of 1-alkyl-, 1-allyl-, and 1-benzyl-1,2,3,9a-tetrahydro-9H-imidazo[1,2-a]indol-2-ones with benzaldehydes in acetic acid and subsequent treatment of the reaction mixture with potassium hydroxide afforded 1-substituted 9a-(2-phenylethenyl)-1,2,3,9a-tetrahydro-9H-imidazo[1,2-a]indol-2-one derivatives. 1-Methyl- and 1-ethyl-9a-[2-(4-dimethylaminophenyl)ethenyl]-1,2,3,9a-tetrahydro-9H-imidazo[1,2-a]indol-2-ones were synthesized by alkylation of 9a-[2-(4-dimethylaminophenyl)ethenyl]-1,2,3,9a-tetrahydro-9H-imidazo[1,2-a]indol-2-one with methyl- and ethyl iodides in DMF in the presence of a strong base.     

The properties of the new Mn(II)–Co(II)–Mn(II)-type hetero-trinuclear oxime metal complexes with N4 and N4O2 ligands

1,3- and 1,2-calix[4]crown-7 and calix[4]crown-9 cone conformers were synthesized in acceptable yields by sequential introduction of two distal or proximal polyethylene glycolic chains with terminal hydroxyls at the lower rim, monotosylation, and intramolecular ring closure reaction. According to the two-phase extraction experiment, the title compounds showed mediocre affinity for alkali and alkaline earth metal picrates. The 1,2-calix[4]crown-9 extracted Sr²⁺ selectively among other alkaline earth metal cations.     

Bis(o-phenylenebis(acetylacetonato))dicopper(II): a strained copper(II) dimer exhibiting a wide range of colors in the solid state

The bis(β-diketone) o-pbaH(2) (o-phenylenebis(acetylacetone), 1) reacts readily with Cu(2+). Although this reaction was expected to yield a trimeric product (2) on geometric grounds, the binuclear complex Cu(2)(o-pba)(2) (3) is obtained instead. Materials containing Cu(2)(o-pba)(2) adopt a variety of colors, depending on the solvents used in preparation: dark green (microcrystalline, 3a), golden-brown (ansolvous, 3b), green-brown (CHCl(3)-C(6)H(6) solvate, 4), dark blue (nitrobenzene solvate, 5), or violet (toluene solvate, 6). Complexes 5 and 6 contain 1D chains of Cu(2)(o-pba)(2) molecules joined by weak Cu···O interactions. Crystalline adducts [Cu(2)(o-pba)(2)L](n) (7 and 8) containing 1D polymeric chains are also obtained upon reaction of 3 with bridging ligands (L = 1,2-bis(4-pyridyl)ethane or 4,4'-bipyridine, respectively). All of the new metal complexes except for 3a have been characterized by X-ray analysis.     

Synthesis of acenaphtho[1,2-x]heterocycles and spiro[acenaphthylene 1-isoxazoles]

Methyl (Z)-(1,2-dihydro-2-oxo-1-acenaphthylenylidene)acetate 1 gives with hydroxylamine the oximes 2 and the pyrrole derivative 4 , whereas with hydrazines affords the pyridazinones 5 and 6 . A pyridazine derivative 8 is also isolated from the reaction of (1,2-dihydro-2-oxo-1-acenaphthylenylidene)acetone 7 with hydrazine hydrate. Reaction between the spiro-derivative 9 and hydroxylamine hydrochloride gives oxime 10 , whereas Wittig olefination of 9 with ylide 11 yields compound 12 which by reaction with 2,4,6-trimethylbenzonitrile oxide ( 13 ) affords the dispiro-derivatives 14 . Finally from the reaction of acenaphthylene-1,2-quinone ( 17 ) with the bisylide 16 the acenaphtho[1,2-c]thiophene ( 18 ) is formed.     

Synthesis and reactivity of 1,2-bis(chlorodimethylgermyl)carborane and 1,2-bis(bromodimethylstannyl)carborane

The 1,2-bis(chlorogermyl)- (1) and 1,2-bis(bromostannyl)carborane (2) have been prepared by the reaction of dilithio-o-carborane with Me(2)GeCl(2) and Me(2)SnBr(2), respectively. Compounds 1 and 2 are found to be good precursors for the synthesis of a variety of cyclization compounds. The Wurtz-type coupling reaction of 1 and 2 using sodium metal afforded the four-membered digerma compound 3 and five-membered tristanna compound 4, respectively. The salt elimination reactions of 1 and 2 using Li(2)N(t)Bu and Li(2)PC(6)H(5) afforded the cyclic products [structure: see text]. The 1,2-bis(dimethylgermyl)carborane 9 and 1,2-bis(dimethylstannyl)carborane 10 were prepared by the reaction of 1 and 2 with sodium cyanoborohydride. The reactions of 9 and 10 with Pd(PPh(3))(4) afforded the bis(germyl)palladium 12 and bis(stannyl)palladium 13 complexes, respectively.     

Synthesis of some novel fused oxo‐ and thiopyrimidines via an intramolecular friedel‐crafts reaction

1H‐Indeno[1,2‐d]pyrimidine‐2,5(3H,9bH)‐dione derivatives 2(a‐i) and 2,3‐dihydro‐2‐thioxo‐1H‐indeno[1,2‐d]pyrimidine‐5(9bH)‐ones 2(j‐q) were synthesized via an intramolecular Friedel‐Crafts reaction between the aryl and ester group of ethyl 6‐methyl‐4‐aryl‐2‐oxo‐1,2,3,4‐tetrahydropyrimidine‐5‐carboxylates 1a‐i , and their thioxo analogs using AlCl₃ and acetyl chloride in nitrobenzene. Yields of the products, after washing with THF, were of the order of 45‐69%. IR and NMR spectroscopy together with elemental analysis were used for identification of these compounds.     

Investigation of the reaction of quinoline with bromine in nitrobenzene

The reaction of quinoline with bromine in nitrobenzene solvent is investigated using the properties of isomolar series. These properties, viscosity, conductivity, density, depression of the freezing point, are determined using a constant molar concentration of C₉H₇N +Br₂, 0.05 per mole of C₆H₅NO₂. It is shown that the nitrobenzene solution of quinoline forms with bromine a complex with the composition C₉H₇N · Br₂. The molecular conductivity of this complex in nitrobenzene solvent increases with dilution.     

乙酰丙酮钌催化硝基苯氢转移氢化制苯胺

以自制的乙酰丙酮钌配合物（Ru(acac)3）为催化剂,甲酸钠为氢供体,十六烷基三甲基溴化铵为乳化剂,研究了水溶液中催化硝基苯氢转移氢化制苯胺的工艺。 确定了适宜反应条件为：甲酸钠和硝基苯摩尔比为2∶1,反应温度80 ℃,反应时间4.0 h,Ru(acac)3用量为硝基苯质量的4%。 硝基苯的转化率和苯胺产率分别为100%和96.65%,表明Ru(acac)3对硝基苯氢转移氢化制苯胺具有优异的催化作用。     

Synthesis of Fluoroalkylated Heterocycles via the Reaction of 3-(1-Hydropolyfluoroalkenyl)-1-oxo-2,4,1-benzoxazines with Dinucleophilic Reagents

The reaction of 3-(1-hydropolyfluoroalkenyl)-1-oxo-2,4,1-benzoxazines 1 with some dinucleophiles was inves-tigated.7-Fluoroalkyl-2,3-dihydro-1,4-diazepine[1,2-d]quinazolin-11-ones 2,2-fluoroalkylisoxazolo[3,2-b]quin-azolin-9-ones 3 and 2-fluoroalkylbenzoimidazoles 4 were obtained from the reaction of 1 with 1,2-diaminoethane,hydroxylamine hydrochloride and 1,2-diaminobenzene respectively.     

Applications of the dicarbollylcobaltate(III) anion in the water/nitrobenzene extraction system

The fundamental properties of the polyhedral sandwich dicarbollylcobaltate(III) anion {[pi-(3)-1,2-B(9)C(2)H(11)](2)Co(III)}(-) are given, together with results for extraction of alkali-metal, alkaline-earth metal and some other cations (e.g., H(+), Pb(2+), Pd(2+) and Ce(3+)) into nitrobenzene and corresponding analytical applications. Considerable attention is paid to charge-transfer through the water-nitrobenzene interface in the presence of this hydrophobic anion.