Synthesis of 2,3-dihydropyrido- and 2,3-dihydropyrimido-[1,4]diazepines from triaminopyridine and triaminopyrimidine

The reaction of 2,3,6-triaminopyridine 1 and 4,5,6-triaminopyrimidine 2 with one equivalent of the chal-cones 3, in acetic acid, leads to the formation of the 8-amino-2,3-dihydro-1H-pyrido[2,3-b][1,4]diazepine and 6-amino-2,3-dihydro-1H-pyrimido[4,5-b][1,4]diazepine derivatives 4 and 5 . The products were characterized by NMR techniques such as ¹³C, ¹H, and DEPT including selective ¹³C{¹H} decoupling experiments.     

Gas-phase reactions of 1,4-benzodioxan, 2,3-dihydrobenzofuran,and 2,3-benzofuran with OH radicals and O3

The kinetics of the gas-phase reactions of 1,4-benzodioxan, 2,3-dihydrobenzofuran, and 2,3-benzofuran with OH radicals and O₃ have been studied at 298 ± 2 K and atmospheric pressure of air and the products have also been investigated. 1,4-Benzodioxan and 2,3-dihydrobenzofuran were chosen as volatile model compounds for dibenzo-p-dioxin and dibenzofuran, respectively. The rate constants, or upper limits thereof, for the O₃ reactions were (in cm³ molecule^?1 s^?1 units): 1,4-benzodioxan, <1.2 × 10^?20; 2,3-dihydrobenzofuran, <1 × 10^?19; and 2,3-benzofuran, (1.83 ± 0.21) × 10^?18. Using a relative rate method, the rate constants for the OH radical reactions (in cm³ molecule^?1 s^?1 units) were: 1,4-dibenzodioxan, (2.52 ± 0.38) × 10^?11; 2,3-dihydrobenzofuran, (3.66 ± 0.56) × 10^?11; and 2,3-benzofuran, (3.73 ± 0.74) × 10^?11. Salicylaldehyde was observed as a product of the OH radical-initiated and O₃ reactions of 2,3-benzofuran, with measured formation yields of 0.26 ± 0.05 and 0.13 ± 0.07, respectively.     

Photoaddition of thiocarboxylic acids to 2,3‐diallyltetraazathiapentalenes

Photoirradiation of acetone solutions of 2,3‐diallyl‐6,7‐dihydro‐5H‐2a‐thia(2a‐S^IV)‐2,3,4a, 7a‐tetraazacyclopent[cd]indene‐ 1,4(2H,3H)‐dithione ( 1 ) in the presence of excess thioacetic acid and thiobenzoic acid afforded addition products, 2,3‐bis(3‐acetylthiopropyl)‐ and 2,3‐bis(3‐benzoylthiopropyl)‐6,7‐dihydro‐5H‐2a‐thia(2a‐S^IV)2,3,4a, 7a‐tetraazacyclopent[cd]indene‐1,4(2H,3H)‐dithiones, respectively, in good yields. These photoaddition reactions were facilitated by the addition of oxygen.     

Zur Konformation von 3-Chlormethylsubstituierten 2,3-Dihydro-1,4-benzoxathiinen

The preferential conformation of some 3-substituted 1,4-benzoxathianes has been determined by means of ¹H n.m.r. spectroscopy.     

The nature of associates of 1,4-dinitrobenzene dianion with 1-butyl-3-methylimidazolium and 1-butyl-2,3-dimethylimidazolium cations

Association of 1,4-dinitrobenzene (1,4-DNB) dianion (DA) with 1-butyl-3-methylimidazolium (bmim⁺) and 1-butyl-2,3-dimethylimidazolium (bdmim⁺) cations, whose salts are widely used as ionic liquids, was studied by cyclic voltammetry. In 0.1 M solution of Bu₄NClO₄ in DMF, associates with the number of coordinated cations up to four in the case of bmim⁺ and two in the case of bdmim⁺ are formed. The partial stability constant values for the associates of bmim⁺ are 40, 20, 5, and 3.2 L mol⁻¹, of bdmim⁺ − 24 and 1.9 L mol⁻¹. The higher number of coordinated bmim+ cations is attributed to the formation of, along with ion pairs, hydrogen bonds between 1,4-DNB DA and bmim⁺ due to the labile hydrogen atom at position 2 of the imidazole ring, in contrast to bdmim⁺, which is involved only into the ion-pair interactions.     

1,4-dioxa-2,3-benzofulvalene from thermolysis of 1,2-benzoquinone 2-diazide

Heated in benzene, 1,2-benzoquinone 2-diazide gives 2-hydroxybiphenyl and 1,4-dioxa-2,3-benzofulvalene (3). Heated in xylene, it gives 3 in 36% yield. Though the PMR spectrum gives no indication of it, the ¹³C NMR spectrum and the dipole moment both reveal considerable dipolar character in 3.     

Synthesis of 2,3-dihydro-1,4-dithiinyl nucleosides via Pummerer-type glycosidation

A straightforward procedure for the preparation of nucleoside analogue 1 and its regioisomer 2 containing a dihydro-1,4-dithiin as sugar moiety has been accomplished in four steps by our readily available heterocyclic system 5. Nucleobase insertion was carried out by direct addition of N⁴-acetylcytosine to sulfoxide derivatives via Pummerer-type glycosidation reaction.     

The synthesis and ultraviolet spectra of some N-aryl-2,3-dihydro-3-oxo-4H-1,4-oxazine derivatives

Two new derivatives of the 1,4-oxazine ring system ( 3a and 3b ) derived from p-aminobenz-amides have been synthesized. The uv absorption spectra of sixteen representative 1,4-oxazines all show two high intensity bands (? ～ 10⁵) between 220-400 ran. The positions and intensities of the absorption maxima have been correlated with the steric and electronic effects of the oxazine ring substituents.     

A Benzylation Study of 2,3-Dichloronaphthazarin

Depending on different reaction time and temperature employed, benzylation of 2,3-dichloronaphthazarin (I) using silver oxide as the catalyst can form either exclusively 5,8-dibenzyloxy-6,7-dichloronaphthalene-1,4-dione (II), or exclusively 5-benzyloxy-2,3-dichloro-8-hydroxynaphthalene-1,4-dione (IV); or a mixture of II and 5,8-dibenzyloxy-2,3-dichloronaphthalene-1,4-dione (III). Structures of these compounds were identified by nmr analysis.     

Triphenylpyrylium salt-sensitized photoreactions of 1,4-diaryl-2,3-dioxabicyclo[2.2.2]octanes through competitive single electron-transfer pathway and proton-catalyzed pathway

2,4,6-Triphenylpyrylium tetrafluoroborate (TPPBF₄)-sensitized photoinduced electron-transfer (PET) reactions of 1,4-diaryl-2,3-dioxabicyclo[2.2.2]octanes 5 (a: Ar¹ = Ar² = p-MeOC₆H₄, b: Ar¹ = Ar² = p-MeC₆H₄, c: Ar¹ = Ar² = Ph) underwent novel fragmentation through their radical cations to give 1,4-diarylbutan-1,4-diones 6 accompanied by elimination of ethylene. On the other hand, 4-aryl-cyclohex-3-en-1-ones 7, p-substituted phenols 8, and 4-aryl-4-aryloxycyclohexanones 9 were produced through proton-catalyzed pathways when the PET reactions of 5 were performed in the absence of a certain base such as 2,6-di-tert-butylpyridine (DTBP). Particularly, the formation of 9 is consistent with the novel cationic rearrangement involving nucleophilic O-1,2-aryl shifts and C-1,4-aryl shifts.     

Synthesis of substituted 1-benzyl-2,4,6-triphenyl-2,3-dihydro-pyrazolo [3,4-b] [1,4]diazepines

The acid catalyzed condensation of 4,5-diaminopyrazoles and chalcones gave the hitherto unknown 1-benzyl-2,4,6-triphenyl-2,3-dihydropyrazolo[3,4-b][1,4]diazepines derivatives. The structure of all products was supported by ir, ¹H and ¹³C-nmr and mass spectra.     

The mass spectral fragmentation of some 2,3-dihydro-5-trifluoromethyl-7-(p-R-phenyl)-1,4-diazepines

Summary Electron impact mass spectra of seven 2,3-dihydro-5-trifluoromethyl/methyl-7-(p-R-phenyl)-1,4-diazepinesR=H, CH₃, OCH₃, CF₃, Cl, Br) have been recorded and are discussed. These systems dissociate by scission of the C₂-C₃ bond followed by loss of H^. to give the [M-H]⁺ ion as the base peak. The fragmentation behaviour has been investigated using metastable scanning techniques and accurate mass measurements. The origin of some characteristic fragment ions is discussed.

---

Massenspektroskopische Fragmentierung einiger 2,3-Dihydro-5-trifluormethyl-7-(p-R-phenyl)-1,4-diazepine

Zusammenfassung Die EI-Massenspektren von 7 2,3-Dihydro-5-trifluormethyl/methyl-7-(p-R-phenyl)-1,4-diazepinen (R=CH₃, OCH₃, CF₃, Cl, Br) werden vorgestellt. Diese Verbindungen fragmentieren unter Spaltung der C₂-C₃-Bindung. Anschließende Abspaltung von H^. führt zum Fragment [M-H]⁺, das als Basispeak auftritt. Das Fragmentierungsverhalten wurde mittels metastabiler Methoden und genauer Massenbestimmungen untersucht. Die Herkunft einiger charakteristischer Fragmentionen wird diskutiert.

     

Mössbauer,far-infrared and Raman spectra of tetrachloro[1,4-di(p-methoxyphenyl)-2,3-dimethyl-1,4-diazabutadiene] tin(IV)

Summary The dependence of the logarithm of the area under the tin-119 Mössbauer resonance (A at different temperatures are normalized toA ₇₇) vs. temperature is measured for tetrachloro[1,4-di(p-methoxyphenyl)-2,3-dimethyl-1,4-diazabutadiene] tin(IV). The slope of the plot of lnA vs.T is –2.46·10^–2K^–1, suggesting a monomeric structure. In the vibrational spectra the significant stretching vibrations agree with acis octahedral configuration of C_2v symmetry.

---

Mössbauer-, Fernes-Infrarot- und Raman-Spektren von Tetrachlor[1,4-di(p-methoxyphenyl)-2,3-dimethyl-1,4-diazabutadien]zinn(IV)

Zusammenfassung Die Abhängigkeit des Logarithmus der Fläche unter der Zinn-119-Mössbauer-Resonanz (A in verschiedenen Temperaturen werden zuA ₇₇ normalisiert) von der Temperatur wurde für Tetrachlor[1,4-di(p-methoxyphenyl)-2,3-dimethyl-1,4-diazabutadien]zinn(IV) gemessen. Der Anstieg lnA gegenT von –2.46·10^–2K^–1 spricht für eine monomere Struktur. In den Vibrations-Spektren stimmen die wichtigsten Dehnungsschwingungen mit einercis-oktaedrischen Konfiguration von C_2v-Symmetrie überein.

     

STUDY ON CATIONIC RING-OPENING COPOLYMERIZATION OF 1,4-ANHYDRO-2,3-DI-O-BENZYL-α-D-RIBOPYRANOSE WITH 1,4-ANHYDRO-2,3-O-ISOPROPYLIDENE-α-D-RIBOPYRANOSE

Cationic ring-opening copolymerization of 1, 4-anhydro-2, 3-O-isopropylidene-α-D-ribo-pyranose (AIRP) with 1,4-anhydro-2,3-di-O-benzyl-α-D-ribopyranose (ADBR) preparedfrom D-ribose was studied. Copolymerization using SbCl_5 or BF_3 OEt_2 as catalyst atlow temperature gave stereoregular (1→4)β-D-ribofuranan (C-1 and C-4 ring cleavagesee Scheme 1) or (1→5) α-D-ribofuranan (C-1 and C-5 ring cleavage) respectively. Theeffects of catalysts, reaction time and temperatures on yield and stereoregularity of the ob-tained polymers were studied. Polymers were characterized by molecular weight, ~1HNMR,~(13)CNMR and optical rotation.     

Titanium and zirconium complexes containing the new 2,3-dimethyl-1,4-diphenylcyclopentadienyl ligand. Synthesis, characterization and polymerization behavior

An easy and inexpensive three-step synthesis of new 2,3-dimethyl-1,4-diphenylcyclopentadiene (3) ligand and the titanium and zirconium homometallocene dichlorides [TiCl₂(η⁵-C₅H-2,3-Me₂-1,4-Ph₂)₂] (4), [ZrCl₂(η⁵-C₅H-2,3-Me₂-1,4-Ph₂)₂] (5), and the mixed ligand zirconium complex [ZrCl₂(η⁵-C₅H-2,3-Me₂-1,4-Ph₂)(η⁵-C₅H₅)] (6) prepared thereof are described. The polymerization of ethene using 4-6/MAO catalysts revealed that zirconocene complexes 5 and 6 displayed moderate and high activity, respectively, whereas the titanium catalyst 4/MAO was inactive. The crystal structures of 4 and 5 were determined by X-ray crystallography.     

Mass spectra of 1H-2,3-dihydro-1,4-benzodiazepine-2-thiones

The mass-spectrometric fragmentation of 1H-2,3-dihydro-1,4-benzodiazepine-2-thiones differs substantially from the fragmentation of the corresponding oxo derivatives with respect to the presence of [M - HCN]⁺ and [M - SH]⁺ ions. This is due to the tautomeric transformation of the molecular ions of the thiones to enethiol and eniminothiol tautomeric forms. The approximate percentages of each of the tautomeric forms were estimated.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1412–1417, October, 1976.     

Preparation of titanocene and zirconocene dichlorides bearing bulky 1,4-dimethyl-2,3-diphenylcyclopentadienyl ligand and their behavior in polymerization of ethylene

New metallocene dichlorides [η⁵-(1,4-Me₂-2,3-Ph₂-C₅H)₂TiCl₂] (2), [η⁵-(1,4-Me₂-2,3-Ph₂-C₅H)₂ZrCl₂] (3) and [η⁵-(1,4-Me₂-2,3-Ph₂-C₅H)η⁵-(C₅H₅)ZrCl₂] (4) were prepared from lithium salt of 1,4-dimethyl-2,3-diphenylcyclopentadiene (1) and [TiCl₃(THF)₃], [ZrCl₄] and [η⁵-(C₅H₅)ZrCl₃(DME)], respectively. Compounds 2-4 were characterized by NMR spectroscopy, EI-MS and IR spectroscopy, and the solid state structure of 3 was determined by single crystal X-ray crystallography. The catalytic systems 3/MAO and 4/MAO were almost inactive in polymerization of ethylene at 30-50 °C, however, they exhibited high activity at temperature 80 °C. The catalyst formed from 2 and excess of MAO was practically inactive at all temperatures.     

Hydrogen atom abstraction and electron transfer of triplet 2,3-dihalo-1,4-naphthoquinones studied by the cidep technique and laser flash photolysis

Investigations using CIDEP techniques showed that an H-atom abstraction from phenol and the electron transfer from 1,2,4,5-tetramethoxybenzene to photoexcited 2,3-dibromo-1,4-naphthoquinone (DBNQ) and 2,3-dichloro-1,4-naphthoquinone (DCNQ) in the polar media originated from their triplet states. Nanosecond laser photolysis at 355 nm was carried out to determine the absorption spectra and coefficients of the corresponding triplet states, semiquinone, and anion radicals for a quantitative investigation of the mechanisms involved in the H-atom abstraction and the electron transfer. The steric hindrance of the substituted groups was indifferent to H-atom abstraction. The electronic structures of triplet DBNQ and DCNQ at 295 K were both revealed to be the mixed states of ³(n,π^*) with a ³(π,π^*) character.     

Electron donor-acceptor interaction of 3,4-dimethylaniline with 2,3-dicyano-1,4-naphthoquinone

The electron donor–acceptor (EDA) interaction between 2,3-dicyano-1,4-naphthoquinone (DCNQ) and 3,4-dimethylaniline (3,4-DMA) is studied in chloroform, dichloromethane and 1:1 (v/v) mixture of chloroform and dichloromethane. The rate of formation of the product was measured as a function of time using UV–vis spectrophotometer. The formation constant (K) and molar extinction coefficient (?) values for the formation of EDA complex were evaluated in the temperature range of 20–35 °C. The pseudo-first-order rate constant (k₁) and the second-order rate constant (k₂) for the disappearance of EDA complex and for the formation of product were evaluated. The activation parameters (ΔH^#, ΔS^# and ΔG^#) of the reaction were determined by temperature dependence of rate constants using the Arrhenius plots. The effect of relative permittivity of the medium on the reaction is discussed. The observed results indicate that formation of final product proceeds through initial formation of EDA complex as an intermediate. The product of the reaction was purified by column chromatography method and identified as 3-(N-3,4-dimethyl-phenylamino)-2-cyano-1,4-naphthoquinone by elemental analysis, IR and NMR spectroscopy. On the basis of kinetic, analytical and spectroscopic results, a plausible mechanism for the formation of EDA complex and its transformation into product is proposed.     

Conformational analysis of trans-2,3-diaryloxy-1,4-dioxanes. A tool for discriminating between steric and electronic effects in the position of

The conformation of several $\text{trans}$-2,3-diaryloxy-1,4-dioxanes has been studied using ¹H NMR techniques. $\text{Trans}$-2,3-bis(4-nitrophenoxy)-1,4-dioxane and $\text{trans}$-2,3-bis(4-methoxyphenoxy)-1,4-dioxane have been found to be predominantly ( ≈98%) in diaxial conformation in CDCl₃). On the other hand, $\text{trans}$-2,3-bis(2,6-dimethylphenoxy)-1,4-dioxane exists in the same conditions as a 66:33 mixture of diaxial and diequatorial conformers. An explanation based on the fulfilment of the exo-anomeric effect is provided.