Synthesis of bridged azabicycles from isoquinolines via a tandem of allylboration and intramolecular metathesis

A method for the synthesis of bridged azabicyclic compounds from isoquinolines was developed. The method is based on a combination of allylboration and ruthenium-catalyzed intramolecular metathesis. Reductive 1,3-diallylation of bromoisoquinolines with triallylborane gave trans-1,3-diallyl-1,2,3,4-tetrahydroisoquinolines. When heated with triallylborane, these compounds yielded mixtures of cis-and trans-isomers in the ratio ∼1: 1. The structure of cis-1,3-diallyl-5-bromo-1,2,3,4-tetrahydroisoquinoline was confirmed by X-ray diffraction analysis. In a similar way, trans-3-allyl-1-vinyl-1,2,3,4-tetrahydroisoquinoline synthesized by sequential vinylation (with vinyllithium) and allylboration of isoquinoline, yielded a mixture of cis-and trans-isomers in the ratio 1.6: 1. Intramolecular metathesis reactions of N-Boc derivatives of cis-isomers in the presence of the Grubbs catalyst (2.0–2.5 mol.%) afforded 7,8-benzo-10-azabicyclo[4.3.1]dec-2-enes or 7,8-benzo-9-azabicyclo[3.3.1]non-2-ene in nearly quantitative yields. Dedicated to Academician V. A. Tartakovsky on the occasion of his 75th birthday. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1510–1515, August, 2007.     

Synthesis and tautomeric transformations of 2-(tert-butyl)-1,2,4-benzotriazine-3(2H)-thiones

Treatment of 2-(tert-butyl)-1,2,3,4-benzotetrazinium tetrafluoroborates with sodium thiocyanate afforded 2-(tert-butylazo)phenyl isothiocyanates 3, which exist in equilibrium with 2-(tert-butyl)-1,2,4-benzotriazine-3(2H)-thiones 3′. The equilibrium depends on the substituents R in the benzene ring: the percentage of the open isomer 3 is about 20% for R = H or Me; for R = Cl or Br, the equilibrium is completely shifted to cyclic isomer 3′. The equilibrium is slow on the time scale of the ¹H and ¹³C NMR experiments. For compounds 3a/3′a (R = H), the spectra at 24 °C show two sets of signals, while those at 0 °C contain only signals for isomer 3′a. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1192–1195, July, 2006.     

1H,13C NMR spectral data for α-, β-, and γ-lewisites and identification ofcis,trans, trans-γ-lewisite as a new isomer

The¹H and¹³C NMR spectral parameters of α-, β-, and y-lewisites1–5 were obtained and a new isomer,cis,trans,trans-γ-lewisite5, was isolated and identified on the basis of chemical shifts, relative intensities of the signals, and the intra-chain (³ J _hh ,³ J _ch ) and interchain (³ J _casch ) coupling constants. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1833–1835, October, 1993.     

Use of polyurethane foam and 3-hydroxy-7,8-benzo-1,2,3,4-tetrahydroquinoline for determination of nitrite by diffuse reflectance spectroscopy and colorimetry

Polyurethane foam (PUF) has been suggested as a solid polymeric reagent for determination of nitrite. The determination is based on the diazotization of end toluidine groups of PUF with nitrite in acidic medium followed by coupling of polymeric diazonium cation with 3-hydroxy-7,8-benzo-1,2,3,4-tetrahydroquinoline. The intensely colored polymeric azodye formed in this reaction can be used as a convenient analytic form for the determination of nitrite by diffuse reflectance spectroscopy (c _min = 0.7 ng mL⁻¹). The possibility of using a desktop scanner, digital camera, and computer data processing for the numerical evaluation of the color intensity of the polymeric azodye has been investigated. A scanner and digital camera can be used for determination of nitrite with the same sensitivity and reproducibility as with diffuse reflectance spectroscopy. The approach developed was applied for determination of nitrite in river water and human exhaled breath condensate.     

Synthesis and photochromic properties of 4-[2-(anthracen-9-yl)-5-methyloxazolyl] fulgide

New photochromic fulgide, viz., 4-{1-[2-(anthracen-9-yl)-5-methyloxazol-4-yl]ethylidene}-3-isopropylidenetetrahydrofuran-2,5-dione, with fluorescent properties was synthesized. Studies by electronic, IR, and ¹H NMR spectroscopy and X-ray diffraction demonstrated that this fulgide exists in the Z form. Light irradiation of its solutions at a wavelength of 365 nm causes Z/E isomerization giving rise to the thermally stable cyclic form. The latter is transformed into the starting E isomer under light irradiation at λ = 436 nm. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 97–101, January, 2006.     

Synthesis and characterization of trichlorogermyl dioic acids: crystal structures and complementary hydrogen bonding motifs in 3-(trichlorogermyl) pentanedioic acid and 2-[(trichlorogermyl)methyl]butanedioic acid

A series of trichlorogermyl-substituted dicarboxylic acids of general formula HOOC–R′–COOH where R′=–CH₂CH(GeCl₃)CH₂– 1, –CH(CH₂GeCl₃)CH₂– 2, –CH(GeCl₃)CH₂– 3 and –CH(CH₃)CH(GeCl₃)– 4 were synthesized by the hydrogermylation reaction of unsaturated acids, such as trans-glutaconic (2-pentenedioic acid), itaconic (methylenebutanedioic acid), fumaric (2-butenedioic acid), and citraconic (2-methyl-2-butenedioic acid) acids with HGeCl₃, which was produced in situ by the reaction of GeO₂ with 37% HCl in presence of NaH₂PO₂ · H₂O. All these compounds were characterized by melting point, CHN analysis, FTIR, and multinuclear NMR (¹H; ¹³C; H,H-COSY). X-Ray crystal structures of 1 and 2 were analyzed to show supramolecular structures in which central Ge atom in each of these structures is four-coordinated with a slightly distorted tetrahedral geometry. Structurally, both compounds adopt supramolecular forms via strong intermolecular O–H–O interactions through 8-membered and 22-membered hydrogen bonded rings. Supplementary material to this paper is available in electronic form at Correspondence: Muhammad Mazhar, Department of Chemistry, Quaid-i-Azam University, Islamabad 45320, Pakistan.     

Antioxidant properties of 2,4-diphenyl-7,8-benzo-5,6-dihydro(4H)selenochromene and 2-<Emphasis Type="Italic">para</Emphasis>-chlorophenyl-4-phenyl-7,8-benzo-5,6-dihydro(4H)selenochromene

The antioxidant properties of 2,4-diphenyl-7,8-benzo-5,6-dihydro(4H)selenochromene and 2-para-chlorophenyl-4-phenyl-7,8-benzo-5,6-dihydro(4H)selenochromene were studied using the initiated oxidation of ethylbenzene and propan-2-ol as model reactions. The antioxidant activity of these compounds was quantitatively characterized by the apparent rate constant of inhibition, fk _in. Addition of 2,4-diphenyl-7,8-benzo-5,6-dihydro(4H)selenochromene to ethylbenzene being oxidized increases the chemiluminescence intensity.     

Synthesis of dihalo derivatives of the 7,8-dimethyldecahydro-7,8-dicarba-nido-undecaborate anion

Treatment of potassium 7,8-dimethyldecahydro-7,8-dicarba-nido-undecaborate with N-chloro-and N-bromosuccinimides in acetonitrile or with an excess of iodine in methanol gave the corresponding dihalo derivatives [9,11-X₂-7,8-Me₂-7,8-C₂B₉H₈]⁻ (X = Cl, Br, or I), which were isolated as alkylammonium salts. The compound (Me₃NH)⁺[9,11-I₂-7-Me-7,8-C₂B₉H₉]⁻ was synthesized by a reaction of K⁺[7-Me-7,8-C₂B₉H₁₁]⁻ with an excess of iodine in methanol. The compounds obtained were characterized by IR and NMR (¹H, ¹¹B, and ¹¹B-¹¹B COSY) spectroscopy. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 888–891, May, 2007.     

Synthesis of Nonsymmetric Dibenzoyldihydromonobenzotetraazacyclo[14]annulenes as Transition Metal Hosts: X-ray Structure of 13,14-Benzo-3,10-di(p-chlorobenzoyl)-5, 8-dihydro-2,4,9,11-tetramethyl-1,5,8,12-tetraazacyclotetradeca-1,3,9,11-tetraene

13,14-Benzo-5,8-dihydro-2,4,9,11-tetramethyl-1,5,8,12-tetraazacyclotetradeca-1,3,9,11-tetraene and 13,14-benzo-3,10-di(p-[X]benzoyl)-5,8-dihydro-2,4,9,11-tetramethyl-1,5,8,12-tetraazacyclotetradeca-1,3,9,11-tetraene, wherein X = CH₃, H, Cl, NO₂ and OCH₃, were synthesized and characterized. IR spectra of the benzoylated compounds showed an intense band assigned to the stretching modes of C==O in the region 1632 ~ 1638 cm⁻¹. Hammett plot of the energies of π → π^* for the compounds was linear with a positive slope (+0.923). ¹H NMR signals exhibited a deshielding effect due to benzoyl groups, while methyl protons only exhibited the shielding effect by the magnetic anisotropy of the group. The substituent effect on ¹³C NMR was similar to that on proton NMR. The cyclic voltammograms of the compounds mostly showed two one-electron irreversible oxidation peaks and one or two reduction waves between −0.280 and −2.500 V depending on the substituents. Hammett plots of 1st and 2nd oxidation potentials (E_op(1) and E_op(2)) were linear with slopes of +0.036 and +0.045, respectively. The structure of the compound 4 (monoclinic, C2/c, a = 26.0059 (19), b = 6.9058 (5), c = 33.082 (2), β = 109.5930°, Z = 8) was determined using X-ray diffraction method.     

Joint X-ray spectroscopic and quantum-chemical study of the electronic structure of pentafluorophenylalkyl ethers

The high resolution X-ray emission O-Kα spectra of pentafluorophenylalkyl ethers C₆F₅OR (R=Et, Prⁱ, and Bu^t) exhibit differences related to a change in the electronic structure of the compounds as R is varied. The search for stable conformers was performed by the semiempirical PM3 method. The most probable structures of C₆F₅OR were determined by the comparison of the experimental and theoretical X-ray spectra plotted for each conformer usingab initio calculations in the 6–31 G basis set. Substituent R in pentafluorophenylalkyl ethers is situated outside of the ring plane. The fluorination of the benzene ring changes the energy level of the lone electron pair of oxygen relative to the levels of orbitals of the ring and substituent R and leads to an increase in the efficiency of interactions in the σ-system. Deceased. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2443–2450, December, 1998.     

A novel series of nickel(II)-dppe-arylazoimidazole complexes. Synthesis and spectroscopic characterization

Reaction of [Ni(dppe)Cl₂/Br₂] with AgOTf in CH₂Cl₂ medium following ligand addition leads to [Ni(dppe)(OSO₂CF₃)₂] and then [Ni(dppe)(RaaiR)](OSO₂CF₃)₂ [RaaiR′ = p–R–C₆H₄–N=N–C₃H₂–NN-1–R′,(1–3), abbreviated as N,N′-chelator, where N(imidazole) and N(azo) represent N and N′, respectively; R = H (a), Me (b), Cl (c) and R′ = Me (1), CH₂CH₃ (2), CH₂Ph (3), OSO₂CF₃ is the triflate anion]. ³¹P{¹H}-NMR confirm that stable bis-chelated square planar Ni(II) azoimine–dppe complex formation with one sharp peaks. The ¹H NMR spectral measurements suggest azoimine link is present with lot of phenyl protons in the aromatic region. Considering all the moities there are a lot of different carbon atoms in the molecule which gives many different peaks in the ¹³C(¹H)-NMR spectrum. In the ¹H-¹H COSY spectrum in the present complexes and contour peaks in the ¹H-¹³C-HMQC spectrum in the present complexes, assign the solution structure and stereoretentive conformation in each complexes.     

Determination of nitrite ions using test strips based on 3-hydroxy-7,8-benzo-1,2,3,4-terahydroquinoline

RIB-Nitrite-Test and Sorbfil-Nitrite-Test strips were developed for determining nitrite ions in water samples and foodstuffs by a reaction similar to the Griess reaction. Stable and noncarcinogenic 3-hydroxy-7,8-benzo-1,2,3,4-tetrahydroquinoline was used as an azo component adsorbed in the reagent paper zone on a polymeric support or on a Sorbfil plate sealed in a transparent polymeric film. Performance characteristics were evaluated by a statistical method for visual test procedures for the detection and determination of NO ₂ ^? using two different test strips. The determination limit was 0.54 and 0.09 mg/L, and the detection limit was 0.50 and 0.08 mg/L, respectively.     

Gold(I)-diphenylphosphinomethane–arylazoimidazole: synthesis and multinuclear NMR investigation

Reaction of [Au₂(dppm)Cl₂] with AgOTf in CH₂Cl₂ medium followed ligand addition and leads to [Au₂(dppm)(RaaiR′)](OTf) [RaaiR′ = p-R–C₆H₄–N = N–C₃H₂–NN–1–R′, (1–3), abbreviated as N,N′-chelator, where N(imidazole) and N(azo) represent N and N′, respectively; R = H (a), Me (b), Cl (c) and R′ = Me (1), CH₂CH₃ (2), CH₂Ph (3), OSO₂CF₃ is the triflate anion, and dppm is the diphenylphosphinomethane-ring]. The ¹H-n.m.r. spectral measurements suggest methylene, –CH₂–, in RaaiEt gives a complex AB type multiplet while in RaaiCH₂Ph it shows AB type quartets with coupling constant of avg. 6 Hz. Considering all the moities there are a lot of different carbon atoms in the molecule which gives a lot of different peaks in the ¹³C-n.m.r spectrum. In the ¹H–¹H-COSY spectrum of the present complexes and contour peaks in the ¹H–¹³C-HMQC spectrum in the present complexes, assign the solution structure and stereoretentive transformation in each step.     

Impact of Transition Metal Substituents on Polysilane Properties: Iron versus Ruthenium

Summary. The previously unknown ruthenio disilanes Rp–Si₂Me₄–C₆H₄X (Rp = η⁵-C₅H₅Ru(CO)₂; X = H, Br, –CHO, CH=C(CN)₂) were synthesized from ClSi₂Me₄C₆H₄X (X = H, Br) and Rp⁻ using conventional chemical methods. Trends in the UV/Vis absorption spectra indicate strong electronic coupling within the Rp–Si–Si–C_aryl fragment and, therefore, closely resemble the ones observed for the corresponding iron complexes. The four compounds however, were shown to be less sensitive towards UV irradiation. The crystal structure of Rp–Si₂Me₄–C₆H₄CH=C(CN)₂ was determined by X-ray diffraction and exhibits an all-trans-array of the Ru–Si–Si–C_aryl moiety, what is a basic requirement for optimal through-bond interaction.     

A novel series of gold(III)-bis-triphenylphosphine-arylazoimidazole complexes: synthesis and spectroscopic and redox study

Reaction of [Au(PPh₃)₂(tht)₂](OSO₂CF₃)₃ with RaaiR′ in CH₂Cl₂ medium following ligand addition leads to [Au(PPh₃)₂(RaaiR′)](OTf)₃ [RaaiR′ = p-R–C₆H₄–N=N–C₃H₂–NN–1–R′, (1–3), abbreviated as N,N′-chelator, where N(imidazole) and N(azo) represent N and N′, respectively; R = H (a), Me (b), Cl (c) and R′ = Me (1), CH₂CH₃ (2), CH₂Ph (3), PPh₃ is triphenylphosphine, OSO₂CF₃ is the triflate anion, tht is tetrahydrothiophen]. The maximum molecular peak of the corresponding molecule is observed in the ESI mass spectrum. The ¹H-nmr spectral measurements suggest methylene, –CH₂–, in RaaiEt gives a complex AB type multiplet while in RaaiCH₂Ph it shows AB type quartets. ¹³C-nmr spectrum suggests the molecular skeleton. In the ¹H–¹H COSY spectrum as well as contour peaks in the ¹H–¹³C heteronuclear multiple-quantum coherence (HMQC) spectrum assign the solution structure. Electrochemistry assign ligand reduction part rather than metal oxidation.     

Lithium 5-(2-diphenylphosphinoethyl)-1,2,3,4-tetramethylcyclopentadienide: Regioselectivity of alkylation of the tetramethylcyclopentadienide anion

Treatment of a mixture of isomeric (2-chloroethyl)-1,2,3,4-tetramethylcyclopentadienes with lithium diphenylphosphide leads to novel 4,5,6,7-tetramethylspiro[2,4]hepta-4,6-diene among the reaction products. The reaction of spiroheptadiene obtained with excess LiPPh₂ at elevated temperature affords lithium 5-(2-diphenylphosphinoethyl)-1,2,3,4-tetramethylcyclopentadienide in almost quantitative yield. the regioselectivity of alkylation of the tetramethylcyclopentadienide anion is estimated from quantum-chemical calculations performedab initio for C₅Mc₄H⁻. The full charges on the ring carbon atoms are determined within the framework of Bader's theory of atomic fragments in molecules. Translated fromIzvestiya Akademii Nauk. Seriya, Khimicheskaya, No. 5, pp. 986–989, may, 1998.     

Synthesis and Structure of Derivatives of 9-(2-Oxopropyl)-1,5-dinitro-7,8-benzo-3-azabicylo[3.3.1]non-7-en-6-ones

A number of 3-R-9-(2-oxopropyl)-1,5-dinitro-7,8-benzo-3-azsbicyclo[3.3.1]non-7-en-6-ones was synthesized by Mannich reaction involving Yanovsky adduct of 2,4-dinitronaphthol. It was established by molecular spectroscopy and X-ray diffraction analysis that the piperidine ring in these compounds was in the chairconformation with a diequatorial position of the substituent attached to the heteroatom and 2-oxo-propyl group, and the cyclohexenone fragment was in sofaform. By an example of 3-methyl-9-(2-oxopropyl)-1,5-dinitro-7,8-benzo-3-azsbicyclo[3.3.1]non-7-en-6-one the dissociative ionization of bicyclononanes under the electron impact was investigated.     

Tellurium-chlorine secondary interactions in palladium(II) complex of MeOC6H4TeCH2CH2NHCH(CH3)C6H4-2-OH resulting in self-assembled bimolecular aggregates with short palladium-palladium distances

A non-Schiff base (Te, N, O) ligand MeOC₆ H₄TeCH₂CH₂NHCH(CH₃)C₆H₄–2–OH (LH) having a chiral center and its palladium(II) complex [PdClL]·CH₂Cl₂ (1) have been synthesized. Both have characteristic ¹H and ¹³C NMR spectra. The single crystal structure of the complex 1 has been determined by X-ray diffraction methods. The monoclinic crystals of 1 (space group P2₁/n) have a=14.581(5) Å, b=13.160(5) Å and c=20.249(5) Å, β=99.398(5)°. The Te $\cdots A non-Schiff base (Te, N, O) ligand MeOC₆ H₄TeCH₂CH₂NHCH(CH₃)C₆H₄–2–OH (LH) having a chiral center and its palladium(II) complex [PdClL]·CH₂Cl₂ (1) have been synthesized. Both have characteristic ¹H and ¹³C NMR spectra. The single crystal structure of the complex 1 has been determined by X-ray diffraction methods. The monoclinic crystals of 1 (space group P2₁/n) have a=14.581(5) ?, b=13.160(5) ? and c=20.249(5) ?, β=99.398(5)°. The TeCl secondary interactions [3.303(2)–3.352(2) ?] between two nearly square planar palladium complex molecules results in a bimolecular aggregate having a PdPd distance 3.203(1) ?. The Pd–Te, Pd–N and Pd–O bond lengths are 2.5005(7)/2.4914(7), 2.060(4)/2.061(4) and 2.054(3)/2.044(3) ?, respectively.     

Synthesis,Spectra and Electrochemistry of Dinitro-bis-{1-alkyl-2-(arylazo) imidazole} Ruthenium(II). Nitro-nitroso Derivatives and Reactivity of the Electrophilic {Ru-NO}<Superscript>6</Superscript>System

Ag⁺ assisted aquation of blue cis-trans-cis-RuCl₂(RaaiR′)₂ (4–6) leads to the synthesis of solvento species, blue-violet cis-trans-cis-[Ru(OH₂)₂(RaaiR′)₂](ClO₄)₂ [Raai R′=p-R-C₆H₄ N=N–C₃H₂–NN–1–R′, (1–3), abbreviated as N,N′-chelator, where N(imidazole) and N(azo) represent N and N′, respectively; R = H (a), OMe (b), NO₂ (c) and R′ = Me (1/4/7/10), CH₂CH₃ (2/5/8/11), CH₂Ph (3/6/9/12)] that have been reacted with NO₂⁻in warm EtOH resulting in violet dinitro complexes of the type, Ru(NO₂)₂(RaaiR′)₂ (7–9). The nitrite complexes are useful synthons of electrophilic nitrosyls, and on triturating the compounds, (7b–9b) with conc. HClO₄ nitro-nitrosyl derivatives, [Ru(NO₂)(NO)(OMeaaiR′)₂](ClO₄)₂ (10b–12b) are isolated. The solution structure and stereoretentive transformation in each step have been established from ¹H n.m.r. results. All the complexes exhibit strong MLCT transitions in the visible region. They are redox active and display one metal-centred oxidation and successive ligand-based reductions. The redox potentials of Ru(III)/Ru(II) (E_1/2^M) of (10b–12b) are anodically shifted by ∼ ∼0.2 V as compared to those of dinitro precursors, (7b–9b). The ν(NO) >1900 cm⁻¹ strongly suggests the presence of linear Ru–NO bonding. The electrophilic behaviour of metal bound nitrosyl has been proved in one case (12b) by reacting with a bicyclic ketone, camphor, containing an active methylene group and an arylhydrazone with an active methine group, and the heteroleptic tris chelates thus formed have been characterised.     

Li+/H+ ion exchange in Li3 ? 2xNbxM2 ? x(PO4)3 (M = In, Fe) materials with a NASICON structure

H_{3 − 2x} Nb _x M_{2 − x} (PO₄)₃ (M = In, Fe) acid phosphates have been obtained by ion exchange from their lithium forms and X-ray powder diffraction, impedance measurements, and ⁷Li and ¹H NMR spectroscopy. The parameters of the hexagonal unit cell of the proton-exchanged forms differ only slightly from those of the initial lithium compounds. According to ¹H NMR data, the proton in the acid phosphates is not hydrated. The conductivity of the acid phosphates at high temperatures depends weakly on their composition and is ∼1.7 × 10⁻⁷ S cm⁻¹ at 620 K. The activation energy of conduction is 30–33 kJ/mol (430–770 K).