Heterocyclization of o-(arylethynyl)arylhydrazines as a new procedure for the synthesis of substituted 1H- and 2H-indazoles and indoles

Procedures for the preparation of 3-substituted 1H- and 2H-indazoles and 2-substituted indoles were developed based on cross-coupling of o-iodoarylhydrazines with copper acetylenides in pyridine or dimethylformamide. An alternative procedure for the synthesis of 3-substituted 1H-indazoles involves cyclocondensation of (2-chloroaryl)acetylenes with hydrazine hydrate in butanol.     

Conversion of Alkyl- and Arylallenes into 1-Alkynes Through Metallated Intermediates

Abstract: A number of acetylenes RCH₂C=CH have been obtained by metallation of the allenes RCH=C=CH₂ or mixtures of acetylenes and allenes with n-BuLi in THF-hexane and hydrolysis after allowing the metallated allenes to rearrange at room temperature or by heating under reflux.     

Cycloaddition Reactions of 3,5-DI-t-Butyl-o-Benzoquinone and Masked 3,5-DI-t-Butyl-o-Benzoquinones with Substituted Acetylenes)

Cycloadditions of 3,5-di-t-butyl-o-benzoquinone with diphenylacetylene, dimethyl acetylenedicarboxylaet, 3-hexyne, phenylacetylene, methyl propiolate, 1-octyne and 3-hydroxy-3-methyl-1-butyne were studied. The reactions occur periselectively across the diene moiety of 3,5-di-t-butyl-o-benzoquinone to give bicyclo[2.2.2]octa-5,7-diene-2,3-diones. In the cases of monosubstituted acetylenes, the reactions take place regioselectively. The selectivities are explained in terms of electronic and steric effects. The cycloadditions of two masked 3,5-di-t-butyl-o-benzoquinones 7 and 8 with monosubstituted acetylenes, phenylacetylene, methyl propiolate, 1-octyne and 3-hydroxy-3-methyl-1-butyne were also examined. Compound 7 reacts with high regioselectivity to give only bicyclo[2.2.2]octa-5,7-diene-2,3-diones 10 upon subsequent hydrolysis; the high regioselectivity was explained as the result of coherent electronic and steric effects. Compound 8 reacts with monosubstituted acetylenes to give either 9 or 10 or both upon subsequent hydrolysis, depending on the nature of the substituents on acetylene. This results from the opposite influences of electronic and steric effects.     

Aminals in the synthesis of 1,3-substituted propargylamines and 3H-2-vinylidene-3-aminobenzofuran derivatives

Aminals of aromatico-hydroxyaldehydes react when heated with terminal acetylenes to form, depending on the reaction conditions and the nature of the starting compounds, 1,3-substituted propargylamines or 3H-2-vinylidene-3-aminobenzofuran derivatives, the structures of which were established by X-ray diffraction.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 455–460, March, 1994.     

Anomalously Large Antiphase Signals from Hyperpolarized Orthohydrogen Using a MOF-Based SABRE Catalyst

Hyperpolarized orthohydrogen (o-H₂) is a frequent product of parahydrogen-based hyperpolarization approaches like signal amplification by reversible exchange (SABRE), where the hyperpolarized o-H₂ signal is usually absorptive. We describe a novel manifestation of this effect wherein large antiphase o-H₂ signals are observed, with ¹H enhancements up to ≈500-fold (effective polarization P_H≈1.6 %). This anomalous effect is attained only when using an intact heterogeneous catalyst constructed using a metal–organic framework (MOF) and is qualitatively independent of substrate nature. This seemingly paradoxical observation is analogous to the “partial negative line” (PNL) effect recently explained in the context of Parahydrogen Induced Polarization (PHIP) by Ivanov and co-workers. The two-spin order of the o-H₂ resonance is manifested by a two-fold higher Rabi frequency, and the lifetime of the antiphase HP o-H₂ resonance is extended by several-fold.     

The thermodynamic properties of 2-ethylhexyl acrylate over the temperature range from <Emphasis Type="Italic">T</Emphasis> → 0 to 350 K

The temperature dependence of the heat capacity C _p ^o= f(T) 2 of 2-ethylhexyl acrylate was studied in an adiabatic vacuum calorimeter over the temperature range 6–350 K. Measurement errors were mainly of 0.2%. Glass formation and vitreous state parameters were determined. An isothermic shell calorimeter with a static bomb was used to measure the energy of combustion of 2-ethylhexyl acrylate. The experimental data were used to calculate the standard thermodynamic functions C _p ^o(T), H ^o(T)-H ^o(0), S ^o(T)-S ^o(0), and G ^o(T)-H ^o(0) of the compound in the vitreous and liquid states over the temperature range from T → 0 to 350 K, the standard enthalpies of combustion Δ_c H ^o, and the thermodynamic characteristics of formation Δ_f H ^o, Δ_f S ^o, and Δ_f G ^o at 298.15 K and p = 0.1 MPa.     

Paradoxes in Thermal Stability of the Liquid-Crystal Phase of Phenylpropargyl Phenyl Ethers: I. Synthesis and Mesogenic Properties of Phenylpropargyl Phenyl Ethers

The ethers PhCCCH₂OC₆H₃RR' were prepared in 51-83% yields by reactions of phenylpropargyl tosylate in alkaline solution with appropriate p- and o-substituted phenols. Below are given R, R', and the ranges of existence of the nematic mesophase (°C): p-I, H, 104-137; p-Cl, H, 65-117; p-F, H, 33-53; p-OMe, H, 79-120; H, H, 44-115; p-(Me)₃C, H, 74-82; p-COOH, H; p-NO₂, H, 77-96; o-NO₂, H, 83-139; o-CHO, H, 75-115; p-Br, o-NO₂, 95-132; p-Cl, o-NO₂, 71-123; p-F, o-NO₂, 79-120; o-Cl, H, none; p-COOPr, H, none; and p-COOPh, H, 116-134. In contrast to the traditional views, the presence of the o-nitro group enhances, rather than distorts, the thermal stability of the mesophase. The stability increases in parallel with the -R effect of the o-substituent.     

The Partial Molar Heat Capacities and Expansions of Inosine, 2′-Deoxyinosine and 2′-Deoxyguanosine in Aqueous Solution at 298.15 K

Solution densities over the temperature range 288.15 to 313.15 K have been measured for aqueous solutions of the nucleosides inosine, 2′-deoxyinosine, and 2′-deoxyguanosine, from which the partial molar volumes of the solutes at infinite dilution, V ₂^o, were obtained. The partial molar expansions for the nucleosides at infinite dilution and 298.15 K, E ₂^o {E ₂^o=(∂ V ₂^o/∂ T) _p }, were derived from the V ₂^o results. The V ₂^o values at 298.15 K for the two sugars D-ribose and 2-deoxyribose also have been determined. The partial molar heat capacities at infinite dilution for all the solutes, C _p,2^o, have been determined at 298.15 K. These V ₂^o,E ₂^o, and C _p,2^o results are critically compared with all of the results available from the literature, and the use of group additivity to evaluate these solution thermodynamic properties for the sparingly soluble nucleoside guanosine is explored.     

TRANSITION METAL,NON-METAL CARBONYL CLUSTRS AS SUPPORTS FOR UNUSUAL ACETYLIDE REACTIVITY

Group 16 elements serve as useful bridging and stabilising single atom ligands in mixed-metal carbonyl complexes and impart unusual reactivity on coordinated acetylenic moieties. Reactions of [Fe ₃ (CO) ₉ (μ ₃ -E) ₂ ] (E = S, or Se) with mononuclear acetylide complexes, [CpM(CO)_3-x(CCR)] (M = Mo or W, x = 0, R = Ph; M = Fe, x = 1, R = Ph or ferrocenyl) under facile conditions yield complexes featuring acetylide coupling, acetylide-flip and formation of oxo and acetylide-bridged complexes. In presence of free acetylenes, unusual ligand systems arising from C─S bond formation are observed and under certain conditions, formation of quinones by coupling of acetylenes with carbon monoxide is facilitated.     

Thermodynamic properties of peptide solutions: 7. Partial molar isentropic pressure coefficients of some dipeptides in aqueous solution

The partial molar isentropic pressure coefficients at infinite dilution, K _S,2 ^o , have been determined for a number of dipeptides in aqueous solution at 25°C. For a series of dipeptides of sequence gly-X, where X is an amino acid with a neutral side chain, the K _S,2 ^o values are all more negative than that for diglycine. The results are discussed in terms of the hydration of the side chains. There are significant differences in the K _S,2 ^o values for sequence isomeric dipeptides. These differences can be rationalized in terms of the mutual interactions between the side chain and the ionic end groups in the dipeptides. Possible relationships between K _S,2 ^o and V ₂ ^o , the partial molar volume at infinite dilution, were investigated. For the dipeptides of sequence gly-X there is an interesting linear relationship between K _S,2 ^o /V ₂ ^o and V ₂ ^o .     

Kinetics of the Complex of Terbium o-methylbenzoate with 1,10-Phenanthroline. Synthesis,decomposition mechanism

The complex of [Tb₂(o-MBA)₆(PHEN)₂] (o-MBA: o-methylbenzoate and PHEN:1,10-phenanthroline) were synthesized and characterized by elemental analysis and IR spectroscopy. The thermal behavior of [Tb₂(o-MBA)₆(PHEN)₂] in dynamic nitrogen atmosphere was investigated by TG-DTG techniques. The thermal decomposition process of the [Tb₂(o-MBA)₆(PHEN)₂] occurred in three consecutive stages at T_p 294, 427 and 512°C. The kinetic parameters and mechanisms of first decomposition stage from analysis of the TG-DTG curves were obtained by the Malek method. This revised version was published online in August 2006 with corrections to the Cover Date.     

Phosphine-Functionalized Syndiotactic Polystyrenes: Synthesis and Application to Immobilization of Transition Metal Nanoparticle Catalysts

The precise control of monomer sequence and stereochemistry in copolymerization is of much interest and importance for the synthesis of high performance materials, but studies toward this goal have met with only limited success to date. The coordination polymerization of diphenylphosphinostyrene (p-StPPh₂ and o-StPPh₂) and its copolymerization with styrene (St) by (C₅Me₄SiMe₃)Sc(CH₂C₆H₄NMe₂-o)₂ have been achieved for the first time to afford a new series of phosphine functionalized syndiotactic polystyrene. By the design of the polymer structure, the copolymer of o-StPPh₂ and St (poly(o-StPPh₂-alt-St)-b-sPS) containing o-StPPh₂ and St atactic alternating copolymer block and syndiotactic polystyrene block (sPS) showed excellent thermal stability and chemical resistance. The simple combination of the triphenylphosphine and syndiotactic polystyrene realized the stable immobilization of metal nanoparticles to afford highly robust metal@poly(o-StPPh₂-alt-St)-b-sPS nanocatalysts at high temperature and various atmospheres. The Cu@poly(o-StPPh₂-alt-St)-b-sPS catalyst can serve as a highly efficient heterogeneous catalyst for the synthesis of quinoline derivatives by acceptorless dehydrogenative coupling of o-aminobenzylalcohol with ketones.     

Synthesis and Structural Studies of Group 2B Transition Metal Complexes with the Bulky Nitrogen Ligand Bis[<Emphasis Type="Italic">N</Emphasis>-(2,6-diisopropylphenyl) imino]acenaphthene

Summary. Group 2B transition metal complexes of bis[N-(2,6-diisopropylphenyl)imino]acenaphthene (o,o-iPr₂C₆H₃-BIAN), namely, [Hg(o,o-iPr₂C₆H₃-BIAN)Cl₂] (1), [Zn(o,o-iPr₂C₆H₃-BIAN)₂](ClO₄)₂ (2), and [Cd(o,o-iPr₂C₆H₃-BIAN)₂](ClO₄)₂ (3) have been synthesized and characterized. In complexes 2 and 3, IR, NMR, and conductivity measurements confirm the coordination of two (o,o-iPr₂C₆H₃-BIAN) ligands to the metal center with two discrete perchlorate anions. X-Ray crystal structure of 1 indicates a distorted tetrahedral geometry with two nitrogen atoms from (o,o-iPr₂C₆H₃-BIAN) ligand and two chloride atoms coordinating to the Hg(II) center.     

Domino synthesis of 2-arylbenzo[b]furans by copper(II)-catalyzed coupling of o-iodophenols and aryl acetylenes

A wide range of 2-arylbenzo[b]furans are synthesized through domino intermolecular C_(aryl)-C_(alkynyl) bond formation followed by intramolecular C_(alkynyl)-O bond forming cyclization via copper(II)-catalyzed coupling of o-iodophenols and aryl terminal acetylenes. This method requires neither expensive palladium catalyst nor oxophilic phosphine ligands, can tolerate different functional groups. The methodology is successfully utilized in formal synthesis of β-amyloid aggregation inhibitor 5-chloro-3-[4-(3-diethylaminopropoxy)benzoyl]-2-(4-methoxyphenyl) benzofuran.     

Synthesis of magnesium catecholate and <Emphasis Type="Italic">o</Emphasis>-semiquinone complexes by oxidation of the metal with 3,6-di-<Emphasis Type="Italic">tert</Emphasis>-butyl-<Emphasis Type="Italic">o</Emphasis>-benzoquinone

Oxidation of amalgamated magnesium metal with 3,6-di-tert-butyl-o-benzoquinone (1) in different aprotic organic solvents afforded magnesium catecholate and bis-o-semiquinolate complexes. The catecholate derivatives of magnesium CatMgL₂ (Cat is the 3,6-di-tert-butyl-o-benzoquinone dianion, L = THF or Py) were synthesized in high yields in pyridine and tetrahydrofuran, respectively. The reactions in diethyl ether or dimethoxyethane produced hexacoordinated metal bis-o-semiquinolates SQ₂MgL_n (SQ is the 3,6-di-tert-butyl-o-benzoquinone radical anion, L = Et₂O, n = 2; L = DME, n = 1). The reaction with the use of toluene as the solvent gave a magnesium bis-o-semiquinolate complex containing the coordinated unreduced o-quinone molecule. The molecular structures of the [CatMgPy₂]₂ and SQ₂Mg·DME complexes were established by X-ray diffraction. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 92–98, January, 2007.     

Synthesis and asymmetric polymerization of a series of methyl‐substituted triphenylmethyl methacrylate

Five novel ortho‐, meta‐, and para‐methyl‐substituted triphenylmethyl methacrylate monomers, such as o‐tolyldiphenylmethyl methacrylate (o‐MeTrMA), di‐o‐tolylphenylmethyl methacrylate (o‐Me₂TrMA), tris‐o‐tolylmethyl methacrylate (o‐Me₃TrMA), tris‐m‐tolylmethyl methacrylate (m‐Me₃TrMA), and tris‐p‐tolylmethyl methacrylate (p‐Me₃TrMA) have been synthesized. The methanolysis rates of these monomers were measured in CDCl₃‐CD₃OD (1:1, v/v) by ¹H NMR spectroscopy at 30 °C. It was found that the order of the methanolysis rates would be TrMA<o‐MeTrMA<o‐Me₂TrMA<o‐Me₃TrMA<m‐Me₃TrMA except p‐Me₃TrMA, which exhibited very good stability to methanolysis. The asymmetric polymerization of these monomers was investigated by chiral anionic complexes as initiators. The results showed that the ability to form a helical chain was effected not only by the types of chiral complex initiators, but also by the position and number of methyl‐substituted groups at the benzene rings of TrMA. The order of the ability of polymerization was o‐MeTrMA >o‐Me₂TrMA>o‐Me₃TrMA and m‐Me₃TrMA> p‐Me₃TrMA>o‐Me₃TrMA. These differences would be attributed to the different sizes and “propeller” steric structures of the bulky side groups. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 430–436, 2001     

Hydroalumination of selenoacetylenes: a versatile generation and reactions of α-aluminate vinyl selenide intermediates in the highly regio and stereoselective synthesis of telluro(seleno)ketene acetals

The hydroalumination of butylseleno acetylenes with DIBAL-H followed by addition of n-butyllithium generated in situ the (Z)-butylseleno vinyl alanates intermediates which were captured with C₄H₉TeBr furnishing the (E)-telluro(seleno)ketene acetals exclusively. The isomers with opposite stereochemistry (Z)-telluro(seleno)ketene acetals were obtained by the reduction of phenylseleno acetylenes with lithium di-(isobutyl)-n-butyl aluminate hydride (Zweifel’s reagent) followed by reaction of (E)-phenylseleno vinyl alanates intermediates with C₄H₉TeBr.     

Synthesis and Structural Studies of Group 2B Transition Metal Complexes with the Bulky Nitrogen Ligand Bis[ N-(2,6-diisopropylphenyl) imino]acenaphthene

Group 2B transition metal complexes of bis[N-(2,6-diisopropylphenyl)imino]acenaphthene (o,o-iPr₂C₆H₃-BIAN), namely, [Hg(o,o-iPr₂C₆H₃-BIAN)Cl₂] (1), [Zn(o,o-iPr₂C₆H₃-BIAN)₂](ClO₄)₂ (2), and [Cd(o,o-iPr₂C₆H₃-BIAN)₂](ClO₄)₂ (3) have been synthesized and characterized. In complexes 2 and 3, IR, NMR, and conductivity measurements confirm the coordination of two (o,o-iPr₂C₆H₃-BIAN) ligands to the metal center with two discrete perchlorate anions. X-Ray crystal structure of 1 indicates a distorted tetrahedral geometry with two nitrogen atoms from (o,o-iPr₂C₆H₃-BIAN) ligand and two chloride atoms coordinating to the Hg(II) center.     

Quinone complexes of aluminum: Synthesis and structures

Reactions of aluminum metal with 3,6-di-tert-butyl-o-benzoquinone (3,6-Q) in various solvents gave aluminum tris-o-semiquinolate and catecholate. The metal catecholate underwent partial hydrolysis in the presence of water. The dimeric complex [(Cat)Al(OH)Bipy]₂ × 4C₂H₄Cl₂ (Cat is the 3,6-Q dianion and Bipy is 2,2-bipyridyne) with bridging OH groups was isolated and characterized by X-ray diffraction. A reaction of aluminum with o-quinone in the presence of molecular iodine yielded the dimeric catecholate iodide [(Cat)₂Al(Et₂O)₂]AlI₂. The structure of the latter was confirmed by X-ray diffraction. An aluminum catecholato-o-semiquinolate complex was obtained by an exchange reaction between [(Cat)₂Al(Et₂O)₂]AlI₂ and thallium o-semiquinolate.     

Effects on Coordination of Thioether Sites. 4. Structural Analysis of η3-Tripodal Ligand Manganese(I) Complexes

Crystal structures of a series of manganese(I) complexes containing tripodal ligands were determined. For [η³-{CH₃C(CH₂PPh₂)₂(CH₂SPh)-P,P′,S}Mn(CO)₃]PF₆ ( 1 ): a = 10.856(3) Å, b = 19.698(3) Å, c = 17.596(5) Å, β = 96.17(2)°, monoclinic, Z = 4, P2₁/c, R(F_o) = 0.068, R_w(F_o) = 0.055 for 3617 reflections with I_o > 2σ(I_o). For [η³-{CH₃C(CH₂PPh₂)(CH₂SPh)₂-P,P′,S}Mn(CO)₃]PF₆ ( 2 ): a = 9.890(2) Å, b = 20.403(4) Å, c = 10.269(3) Å, β = 117.44(2)°, monoclinic, Z = 2, P2_l, R(F_o) = 0.050, R_w(F_o) = 0.037 for 1760 reflections with I_o > 2σ(I_o). For [η³-{CH₃C(CH₂PPh₂)₂(CH₂S)-P,P′,S}Mn(CO)₃] ( 4 ): a = 8.191(7) Å, b = 10.495(3) Å, c = 19.858(6) Å, α = 99.61(2)°, β = 96.17(2)°, γ = 92.70(4)°, triclinic, Z = 2, P-I, R(F_o) = 0.048, R_w(F_o) = 0.039 for 2973 reflections with I_o > 2σ(I_o). There is no significant difference in the bond lengths of Mn-S bonds among three species in their crystal structures [2.325(2) Å in 1; 2.358(4) in 2; 2.380(2) in 4], but the better donating ability of thiolate in complex 4 appears on the lower frequencies of its carbonyl stretching absorptions.