Theoretical Investigation of the Additivity of Structural Substituent Effects in Benzene Derivatives

The additivity of substituent effects in 1,3- and 1,4-disubstituted C₆H₄X₂, and 1,3,5-trisubstituted C₆H₃X₃ (X=F, Cl, CN, NO₂, CH₃, CF₃, NH₂, OH) benzene derivatives on the ring geometry has been investigated. The analysis is based on ab initio calculations at the MP2/6-31G** level of theory. The substituent impacts on the benzene ring are generally in good agreement with the results reported in earlier experimental and lower level theoretical studies. The impacts determined in the monosubstituted benzenes were used to estimate the ring distortions in the di- and trisubstituted derivatives. The estimated ring CC bond distances agree generally within 0.001 Å and the estimated CCC bond angles within 0.3 degree, with the optimized ones. The best agreement (deviations up to only 0.0003 Å and 0.03 deg.) between the estimated and optimized geometrical parameters was obtained for the CH₃ derivatives. Generally, the para-disubstituted derivatives showed the best compliance with additivity, somewhat poorer agreement characterized the meta derivatives while the trisubstituted derivatives showed angular distortions of up to about 0.4°.     

A comparative,vapor-phase (G.L.C.-M.S.) study of various derivatives of prostaglandins A and B

The isomeric prostaglandins, A and B, can be readily distinguished by differences in the mass spectra of their derivatives. The mass spectra of the PGA₁- or PGA₂-methyl ester (ME)-trimethyl silyl (TMS) ether derivatives have a prominent ion at [M ? 71]⁺ or [M ? C₅H₁₁]⁺ while those of the PGB₁- or PGB₂-ME-TMS derivatives have a predominant ion at [M ? 99]⁺ or [M ? C₆H₁₁O]⁺ in addition to that at [M ? 71]⁺. Ions of similar origin characterize the spectra of the PGA₁- or PGA₂-TMS ether-TMS ester and PGB₁- or PGB₁-TMS-TMS derivatives, respectively. The fragmentation of other derivatives of PGA₁, PGA₂, PGB₁ and PGB₂ such as the ME-t-Bu-DMS (t-butyl-dimethylsilyl ether); ME-MO (methoxime)-TMS; ME-MO-Ac (acetate), and ME-Ac are also described comparatively. The composition of important ions was confirmed by deuterium labeling and/or high resolution mass spectroscopy, where appropriate. The potential advantages and limitations of the derivatives for quantitative analysis of prostaglandins by the specialized technique of multiple ion detection (MID) are described.     

Preparation of tetrahydrocyclopenta[b]indoloquinones

The nitration of N-acyl-7-methyl-1,3a,4,8b-tetrahydrocyclopenta[b]indole with a mixture NH₄NO₃-(CF₃CO)₂O afforded 5-nitro derivatives whose reduction with Fe(OH)₂ in H₂O led to the formation of 5-amino derivatives. The oxidation of the 5-amino derivatives with Fremy’s salt gave the corresponding indoloquinones.     

CoFe2O4@SiO2-PA-CC-guanidine nanoparticles: A novel,efficient, and recyclable catalyst for the synthesis of 3,5-disubstituted-2,6-dicyanoaniline derivatives

A new and efficient procedure for the synthesis of 3,5-disubstituted-2,6-dicyanoaniline derivatives by CoFe₂O₄@SiO₂-PA-CC-guanidine magnetic nanoparticles (MNPs) was reported. 3,5-Disubstituted-2,6-dicyanoaniline derivatives were synthesized from malononitrile, aldehydes, and β-nitrostyrene derivatives in good yields. MNPs used for the synthesis of aniline derivatives were easy to recover and reuse. The CoFe₂O₄@SiO₂-PA-CC-guanidine MNPs were characterized by Fourier-transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, thermogravimetric analysis, and vibration sample magnetometry techniques.     

Extended conjugated mesogens: synthesis and mesomorphic properties of H-shaped mesogens based on 3,3ʹ,5,5ʹ-tetrasubstituted 2,2ʹ-bithiophene with oligo(1,4-phenyleneethynylene) arms

A new class of extended conjugated mesogens, namely H-shaped mesogens based on 3,3?,5,5?-tetrasubstituted 2,2?-bithiophene with oligo(1,4-phenyleneethynylene) arms, have been synthesised, and the relationships between molecular structures and mesomorphic properties investigated. Tetraalkyl, tetraalkoxy and dialkyldialkoxy derivatives, [R¹C₆H₄CCC₆H₂(C₂H₅)₂CC]₂[R²C₆H₄CCC₆H₂(C₂H₅)₂CC]₂C₈H₂S₂ where R¹ and R² = alkyl and alkoxy chains of different lengths, exhibit nematic phases. The length, number and position of the terminal chains strongly affect the mesomorphic properties. The tetraalkyl derivatives in which R¹ = R² = pentyl to heptyl exhibit enantiotropic mesophases, whereas the derivatives with octyl or nonyl chains exhibit monotropic mesophases. The tetraalkoxy derivatives in which R¹ = R² = pentyloxy to nonyloxy all exhibit enantiotropic nematic phases. The mesophase range increases with increasing alkoxy chain length, except that the octyloxy and nonyloxy derivatives have almost the same temperature range. The dialkyldialkoxy derivatives in which R¹ = alkyl; R² = alkoxy and in which R¹ = alkoxy; R² = alkyl (R¹ and R² = heptyl, nonyl, hexyloxy or nonyloxy) exhibit enantiotropic mesophases. The derivatives in which R¹ = alkoxy have a significantly lower crystal–nematic transition temperature than the corresponding derivatives (R² = alkoxy), although the two types of derivatives have a similar nematic–isotropic transition temperature.     

A highly sensitive and fast responsive fluorescent probe for SO2 derivatives and its application in living cell imaging

Abstract

A new fluorescence probe 1 for sulfur dioxide derivatives has been developed which acts through nucleophilic addition of the derivatives and shows high stability, specificity, and sensitivity. In the presence of SO₂ derivatives, the fluorescence intensity of probe 1 significantly decreases within a short time period of 40?s, along with a low detection limit of 0.32?µM. Fluorescence imaging capability of probe 1 was also investigated, showing clear detection of SO₂ derivatives in living cells. The results indicate that this probe has a great potential for the detection of SO₂ derivatives in broad biological and relevant samples.     

Facile synthesis of some novel pyrrole and pyridazinoquinazolone derivatives

3-Dicyanomethylene-3-phenylpropionitrile coupled with diazotized aromatic amines (Ar-NH₂) to afford hydrazono derivatives. The latter (Ar = C₆H₅, 4-CH₃C₆H₄, 4-CH₃OC₆H₄, and 4-ClC₆H₄) were readily cyclized upon reflux in aqueous NaOH to 3(2H) pyridazinimine derivatives, which were readily transformed into their corresponding pyridazinone derivatives on reflux in ethanolic HCl. The pyridazinimines undergo reductive cleavage and recyclization via loss of ammonia to afford the corresponding N-aryl pyrroles on reflux in glacial acetic acid with Zn dust. The pyridazinone derivatives, however, undergo the same reaction but with loss of the aromatic amine moiety to afford only one pyrrolone derivative. The hydrazono derivative (Ar = 2-NCC₆H₄) was cyclized into pyridazino[3,2-b]quinazolin-6-imine, which is easily converted into pyridazino[3,2-b]quinazolin-6-one on reflux in ethanolic HCl. The latter compound is also obtained from the hydrazo derivatives (Ar = 2-HOOCC₆H₄ and 2-MeOOCC₆H₄) by reflux in aqueous NaOH.     

2-Pyridone and 3-oxo-1,2,6-thiadiazine-1,1-dioxide derivatives: a new class of hydrogen bond equivalents of uracil

Hydrogen bond complex stability between adenine (A) and hydrogen bond equivalents of uracil: 2-pyridone derivatives (U^X _X2O) and 3-oxo-1,2,6-thiadiazine-1,1-dioxide derivatives (U^X _SO2) was studied, and as the result, the hydrogen bond energy of U^X _X2O-A and a complex of UX^X _SO2-A, was about 1.5 kcal/mol more stable than that of the corresponding adenine-uracil derivatives complex, respectively. The energy difference between the imide tautomer and enol tautomer was smaller than those of uracil derivatives. U^F _SO2 can form a stable complex with A, and its imide tautomer is stable.     

Highly selective hydroarylation of propiolic acid derivatives using a PtCl2/AgOTf catalytic system

Hydroarylation of propiolic acid derivatives with arenes in trifluoroacetic acid efficiently proceeded in the presence of PtCl₂/AgOTf catalyst to give cis-cinnamic acid derivatives in good to high yields. This PtCl₂/AgOTf-catalyzed reaction did not afford any 4-arylbuta-1,3-diene-1,3-dicarboxylic acid derivatives formed by Pd(OAc)₂-catalyzed hydroarylation. The specific optimization of the catalytic hydroarylation and application to electron-rich arenes are reported.     

Photobase generation from amineimide derivatives and their use for curing an epoxide/thiol system

The structural effects of amineimide derivatives on photobase generation and the use of the resultant base for thermal curing of an epoxide/thiol system are investigated. The results of UV spectral change and gas chromatographic‐mass spectrometric analysis indicated that amineimide derivatives undergo photolysis by UV irradiation and generate bases. The order of conversion of the photolysis for the functional groups introduced to amineimide derivatives was NO₂ > N(CH₃)₂ > CN > OCH₃ > H. By using aminimide derivatives with NO₂ and N(CH₃)₂ groups, the curing of the epoxide/thiol system was shifted to lower temperature after UV irradiation. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 4045–4052, 2002     

Photoelectron spectroscopy study of the triphenyl derivatives of the group IV elements

The photoelectron He(I) spectra of several phenyl derivatives of the Group IV elements are reported, and the first few bands are assigned to the corresponding MO's. A sizable interaction among the π orbitals of the rings has been found for the carbon derivatives HCPh₃, HC(mesityl)₃ and H₂CPh₂, but not for the Si, Ge and Sn triphenyl derivatives. The exceptional behaviour of the carbon compounds has been attributed to the short central atom—ring distance, by analogy with findings for the Group V triphenyl derivatives.The charge transfer from the rings towards the Si atom is substantially reduced compared with that in H₃SiPh.     

Theoretical investigations on structure,density, detonation properties,and sensitivity of the derivatives of PYX

The ? NH₂, ? NO₂, ? N₃, ? NHNO₂, and ? ONO₂ substitution derivatives of PYX (2,6‐bis(picrylamino)‐3,5‐dinitropyridine) were studied at the B3LYP/6‐31G** level of density functional theory. The sublimation enthalpies and heats of formation (HOFs) in gas phase and solid state of these compounds were calculated. The theoretical predicted density (ρ), detonation pressure (P), and detonation velocity (D) showed that these derivatives have better detonation performance than PYX. The effects of substituent groups on HOF, ρ, P, and D were discussed. The order of contribution of various groups to P and D was ? ONO₂ > ? NO₂ > ? NHNO₂ > ? N₃ > ? NH₂. Sensitivity was evaluated using the frontier orbital energies, bond orders, bond dissociation enthalpies (BDEs), and characteristic heights (h₅₀). The trigger bonds in the pyrolysis process for these PYX derivatives may be Ring‐NO₂, NH? NO₂, or O? NO₂ varying with the substituents. The h₅₀ of most compounds are larger than that of CL‐20, and those of ? NH₂, ? NO₂, and most ? ONO₂ derivatives are larger than that of RDX. The BDEs of the trigger bonds of all but the ? ONO₂ derivatives are sufficiently large. Taking both detonation performance and sensitivity into consideration, some derivatives of PYX may be good candidates of explosives. © 2012 Wiley Periodicals, Inc.     

Chemistry of C84: Separation of Three Constitutional Isomers and Optical Resolution of D2-C84 by Using the “Bingel–Retro-Bingel” Strategy

The pure enantiomers of D ₂ -C ₈₄ as well as a third constitutional isomer of this higher fullerene were produced by a retro-Bingel reaction on the first organic derivatives of C₈₄ (see scheme). These derivatives were synthesized by Bingel cyclopropenation of C₈₄, separated, and unambiguously structurally characterized.     

13C NMR study of polarizations and polarization ranges of vinylene groups in seven series of related compounds

Polarizations, polarization ranges and ratios of polarization ranges for vinylene groups in seven series, namely chalcone derivatives, ferrocene analogues of chalcone, stilbene derivatives, ferrocene analogues of stilbene, and styrene derivatives, were studied. The polarization ranges spanning the intervals between ¹³C NMR chemical shifts of the derivatives substituted by p-NO₂ and p-NMe₂ groups are compared in these related compounds. The influence of the side-chain groups in the vinylene moiety and of the sign of the polarization on the substituent-effect are discussed.     

Degradation of phenylarsonic acid and its derivatives into arsenate by hydrothermal treatment and photocatalytic reaction

The degradation of phenylarsonic acid (PA) and its derivatives by hydrothermal treatment (HTT) was examined, especially focusing on the effect of adding H₂O₂ upon the degradation efficiency. The degradation was assessed by the generation of arsenate resulting from the cleavage of As C bonds in the PA derivatives. When PA (without substituents) was subjected to an HTT with H₂O₂ (H₂O₂‐HTT; 0.5–1% H₂O₂) at 175–200 °C, PA was almost completely degraded into arsenate, whereas an HTT with NaOH (NaOH‐HTT; 3 M NaOH) at the temperatures provided almost no degradation. The H₂O₂‐HTT also worked well for the degradation of PA derivatives with hydroxy and/or nitro groups on the phenyl ring. However, the degradation of aminophenylarsonic acids was not favorably performed by the H₂O₂‐HTT. The effect of the structure of PA derivatives upon the degradation susceptibility was discussed. A photocatalytic reaction using TiO₂ was also attempted for the degradation of PA derivatives. Copyright © 2005 John Wiley & Sons, Ltd.     

Electrochemical properties of palladium(0) complexes coordinated by quinone derivatives

The polagrophic and cyclic voltammetric behavior of quinone derivatives (Q) and their palladium(0) complexes, (Q)₁ or ²Pd(PPh₃)₂, has been studied. All free quinone derivatives except 5,8,9,10-tetrahydro-1,4-naphthoquinone (THNQ) showed two reversible waves, and all palladium(0) complexes showed irreversible waves. The reduction half-wave potentials for free quinone derivatives lie in the following order:7,7,8,8-tetracyanoquinodimethane (TCNQ) ? p-benzoquinone (BQ) ? 5,8-dihydro-1,4-naphthoquinone (DHNQ) ? 1,4-naphthoquinone (NQ) ? THNQ. The reduction potentials for quinone derivatives shifted toward the negative or coordination to palladium(0). The extents of the shifts depended on the electron-withdrawing ability of the free quinone derivatives. On the other hand, the oxidation potentials for the central palladium(0) in their complexes showed more positive values in comparison with the potential for Pd(PPh₃)₄. However, the oxidation potentials were almost constant for all complexes of the quinone derivatives. On the basis of these facts, the phenomena of charge transfer in the complexes are discussed.     

C(1)-Phenethyl Derivatives of [closo-1-CB11H12]− and [closo-1-CB9H10]− Anions: Difunctional Building Blocks for Molecular Materials

C(1)-vinylation of [closo-1-CB₉H₁₀]⁻ ( A ) and [closo-1-CB₁₁H₁₂]⁻ ( B ) with 4-benzyloxystyryl iodide followed by hydrogenation of the double bond and reductive deprotection of the phenol functionality led to C(1)-(4-hydroxyphenethyl) derivatives. The phenol functionality was protected as the acetate. The esters were then treated with PhI(OAc)₂ and the resulting isomers were separated kinetically (for derivatives of anion A ) or by chromatography (for derivatives of anion B ) giving the difunctionalized building blocks in overall yields of 9 % and 50 %, respectively. A similar series of reactions was performed starting with anions A and B and 4-methoxystyryl bromide and iodide. Significant differences in the reactivity of derivatives of the two carborane anions were rationalized with DFT computational results. Application of the difunctionalized carboranes as building blocks was demonstrated through preparation of two ionic liquid crystals. The extensive synthetic work is accompanied by single crystal XRD analysis of six derivatives.     

SYNTHESIS OF FUSED AND SPIRO HETEROCYCLIC COMPOUNDS DERIVED FROM 3,5-PYRAZOLIDINEDIONE DERIVATIVES

Abstract

The reaction of compound 1 with triethyl orthoformate afforded 2, which in turn reacted with CS₂ and active methlyene compounds or malononitrile to give dithiolane and 4-malononitrile methylene derivatives 3,4, respectively. Treatment of compound 4 with active methylene compounds afforded spiro cyclopentene derivatives 5_a-c. Compound 1 was reacted with bromomalononitrile or CS₂ and halocompounds to afford furo-. thieno- and dithiolano-pyrazole derivatives 6–11, respectively. The reaction of compound 12 with phenacyl bromide or benzylidenemalononitrile furnished oxathiol-2-ylidene and pyridinethione derivatives 13,14, respectively. The dibromo derivative 16 was reacted with CS₂ and active methylenes or malononitrile to obtain spiro dithietanes 17a-e and 4-dicyano-methlyene derivative 22, respectively. Compounds 17 underwent a cycloaddition reaction with thioglycolic acid, N-phenylbenzohydrazindoyl bromide, 2,5-dimethylfuran and 1-phenyl-3,5-pyrazolidinedi one to give cycloadducts 18–21, respectively. Treatment of > o-aminothiophenol or o-phenylenediamine with the dicyano compound 22 leads to the formation of spiro thiazepine or spiro diazine derivatives 23_a,b . The arylidene derivatives 24 was reacted with S,S-acetals, N,S-acetals or ammonium dithiocarbamate to afford dithiane, oxazine or pyrazolodithiocarbamate derivatives 25–29, respectively. Chemoselective cyclization of compound 29 with H₂SO₄, NaOH or MeI gave compounds 30–32, respectively. Benzopyrano derivatives 34,36 were obtained through the reaction of compound 1 with a mixture of thiourea, triethyl orthoformate and ethyl cyanoacetate or with cyanoketene S,S diacetals, respectively.     

Synthesis of [60]fullerene-glycopyranosylaminopyrimidin-4-one conjugates

The synthesis of several C₆₀ derivatives containing a 6-(β-d-glycopyranosylamino)pyrimidin-4-one unit and a C₆₀-uridine conjugate is described. The fullerene derivatives bearing a 4-(β-d-glycopyranosylamino)pyrimidin-4-one moiety were synthesised by 1,3-dipolar cycloaddition reactions of C₆₀ with azomethine ylides generated in situ from the corresponding 5-formylpyrimidin-4-one derivatives and N-methylglycine. The synthesis of the C₆₀-uridine conjugate involved the selective protection of the 2′- and 3′-hydroxyl groups of uridine, esterification, cyclopropanation of C₆₀ and, finally, the deprotection of the hydroxyl groups. One of the fullerene-glycopyranosylaminopyrimidin-4-one conjugates was characterised by single-crystal X-ray crystallography. Differentiation between pairs of diastereoisomers, for several fullerene derivatives, was achieved through the study of their gas-phase fragmentations.     

Phosphine-substituted ruthenium carbonyl carboxylates

The behaviour of the [Ru₂(CO)₄(CH₃COO)₂]_n/tributylphosphine/acetic acid system has been investigated as a function of reaction conditions and molar ratios of reactants. Tricyclohexylphosphine and triethylphosphite were also used as ligands and investigation was extended to the related oxalic, malonic, succinic, glutaric and adipic acid derivatives. These derivatives were isolated and characterized in view of their possible role as catalysts in the homogeneous hydrogenation of carboxylic acids in the presence of phosphine- or phosphite-substituted ruthenium carbonyl derivatives.