Effects of neutral and charged substituents on the infrared carbonyl stretching frequencies in phenyl and alkyl benzoates in DMSO

The carbonyl infrared stretching frequencies for 57 meta‐, para‐ and ortho‐substituted phenyl benzoates, C₆H₅CO₂C₆H₄‐X and alkylbenzoates, C₆H₅CO₂R, containing besides neutral substituents the charged substituents in phenoxy and alkoxy part in dimethyl sulfoxide (DMSO) have been recorded. The carbonyl stretching frequencies, ν_CO, for meta‐ and para‐substituted phenyl esters of benzoic acids in the case of neutral substituents were found to correlate well with the substituent constants, σ°. The ν_CO values for ortho derivatives correlated with the inductive substituent constants, σ_I, only. The values of constants for charged substituents, σ°_±, calculated on the basis of the ν_CO and the ¹³C NMR chemical shifts, δ_CO, in DMSO agree well with the σ°_± values for the corresponding ion pairs reported by Hoefnagel and Wepster and those determined from the log k values of the alkaline hydrolysis in 4.4 M NaCl solution at 50 °C. Thus, the values of substituent constants for ion pairs of charged substituents estimated on the basis of aqueous data could be successfully used in non‐aqueous solution (DMSO) simultaneously with neutral substituents in case the charged substituents were not completely ionized and are in ion pair form. Copyright © 2016 John Wiley & Sons, Ltd.     

新型直链淀粉类手性固定相的制备与手性拆分性能

通过对糖单元2-位进行选择性酯化以及6-位保护与去保护,运用区域选择性方法合成了5种新型直链淀粉类衍生物,分别为直链淀粉-2-苯甲酸酯-3-(4-氯苯基氨基甲酸酯)-6-(3,5-二甲基苯基氨基甲酸酯)、直链淀粉-2-苯甲酸酯-3-(4-氯苯基氨基甲酸酯)-6-(3,5-二氯苯基氨基甲酸酯)、直链淀粉-2-苯甲酸酯-3,6-二(4-氯苯基氨基甲酸酯)、直链淀粉-2-(4-氯苯甲酸酯)-3,6-二(3,5-二氯苯基氨基甲酸酯)和直链淀粉-2-(4-氯苯甲酸酯)-3,6-二(环己基氨基甲酸酯),并将其涂覆在氨丙基硅胶表面制备了HPLC手性固定相。利用核磁共振-氢谱(¹H-NMR)和傅里叶变换红外光谱(FT-IR)技术对所合成衍生物的结构进行了表征和分析,并用HPLC法评价所合成衍生物的手性识别能力。与具有单一取代基直链淀粉类手性固定相的对比分析表明,所合成的新型直链淀粉类手性固定相对于某些对映体具有更为优异的拆分结果。进一步分析表明,2-、3-和6-位取代基的性能和引入位置对直链淀粉衍生物的手性识别能力均有较大的影响。     

Selective synthesis of 2-(5-oxo-1-arylhex-1-yn-3-yl)phenyl benzoates via FeCl3-mediated cascade reactions of propargylamines with β-enamino ketones

A mild and efficient FeCl₃-mediated cascade reaction of ortho-hydroxyl propargylamines with β-enamino ketones has been developed. This protocol provided a practical and selective method to synthesize 2-(5-oxo-1-arylhex-1-yn-3-yl)phenyl benzoates via in situ generated alkynyl o-quinone methides following a cascade intermolecular 1,4-conjugate addition/intramolecular nucleophilic addition/reverse Claisen condensation/hydrolysis pathway. Furthermore, a series of 2-(3-oxo-1-arylbutyl)phenyl benzoates with good functional group tolerance were prepared in good to high yields under these reaction conditions.     

氯化铵三氧化铬在干反应中对苄醚的选择性氧化

本文报道氯化铵三氧化铬(ACC)是具有高选择性的氧化剂, 在无溶剂的干反应中, 可以把苄醚氧化成相应的苯甲酸酯, 且顶点满意的产率.     

Exceptionally high in vitro antitumor activity of substituted triphenyltin benzoates including salicylates against a human mammary tumor,MCF-7, and a colon carcinoma,WiDr

Nine new substituted triphenyltin benzoates of the type Ar₃Sn? OOC? C₆H₂XYZ [X = Y = H, Z = 2-OCH₃ and 4-F; X = H, Y = 3-F, Z = 5-F; X = H, Y = 2-OH, Z = 5-Cl, 5-NH₂, 5-OCH₃ and 5-SO₃H; X = 2-OH, Y = 3-CH(CH₃)₂ and Z = 5-CH(CH₃)₂] were prepared and possess considerable in vitro antitumor activity against two human tumor cell lines (MCF-7, a mammary tumor, and WiDr, a colon carcinoma) comparable with that of mitomycin C.     

Influence of ortho substituents on 17O NMR chemical shifts in phenyl esters of substituted benzoic acids

¹⁷O NMR spectra for 29 phenyl esters of ortho‐, para,‐ and meta‐substituted benzoic acids, X‐C₆H₄CO₂C₆H₅, at natural abundance in acetonitrile were recorded. The δ(¹⁷O) values of carbonyl and the single‐bonded oxygens for para derivatives gave good correlation with the σ⁺ constants. The δ(¹⁷O) values for meta derivatives correlated well with the σ_m constants. The influence of ortho substituents on the δ(¹⁷O) values of carbonyl oxygen and the single‐bonded oxygens was analyzed using the Charton equation containing the inductive, σ_I, resonance, σ⁺_R, and steric, E, substituent constants. For ortho derivatives, excellent correlations with the Charton equation were obtained when the data treatment was performed separately for derivatives containing electron‐donating +R and electron‐attracting ?R substituents. The electron‐donating substituents in ortho‐, meta‐, and para‐substituted esters resulted in shielding of the ¹⁷O signal and the electron‐withdrawing groups caused deshielding. In phenyl ortho‐substituted benzoates, the substituent‐induced positive inductive (ρ_I > 0), resonance (ρ_R > 0), and steric (δ_orthoE > 0) effects were found. The steric interaction of ortho substituents with ester group was found to produce a deshielding effect on the carbonyl and single‐bonded oxygens. For ortho derivatives with ?R substituents, the resonance term was insignificant and the steric term was ca. twice weaker as compared to that for derivatives with +R substituents. The δ(¹⁷O) values for ortho‐substituted nitrobenzenes, acetophenones, and benzoyl chlorides showed a good correlation with the Charton equation as well. In ortho‐substituted nitrobenzenes the inductive, resonance and steric effect were found to be ca. 1.7 times stronger as compared to that for phenyl ortho‐substituted benzoates. Copyright © 2010 John Wiley & Sons, Ltd.     

Novel mesogenic asymmetric diacylhydrazines: synthesis,mesomorphic behaviour and X‐ray study

The synthesis and liquid crystalline properties of a new series of diacylhydrazine derivatives (2a–g) are reported. All compounds of series 2 exhibit a smectic C (SmC) phase. The first homologues (2a, 2b) display a monotropic SmC mesophase, whereas the highest homologues (2c–g) exhibit an enantiotropic SmC phase. The liquid crystalline properties were investigated by differential scanning calorimetry, polarizing optical microscopy and X‐ray measurements.     

Effect of exchange of terminal substituents on the mesophase behaviour of some azo/ester compounds

Six homologous series of 4-(4′-alkoxy phenylazo) phenyl 4″-substituted benzoates (In_a-f) were prepared in which, within each homologous series, the length of the terminal alkoxy chain varies between 6, 8, 10, and 12 carbons, while the other terminal substituent, X, is a polar group that alternatively changed from CH₃O, CH₃, H, Br, NO₂ and CN. Compounds prepared were characterised by spectroscopic methods, and their mesophase behaviour investigated by differential scanning calorimetry (DSC) and polarised optical microscopy (POM). The results were discussed in terms of mesomeric and polarisability effects. In each group of compounds, bearing the same alkoxy substituent, the nematic-to-isotropic transition temperatures (T_C) were successfully correlated with the polarisability anisotropy of bonds to the substituent X. A comparative study was made between the investigated compounds and their previously prepared isomers, namely, 4-(4′-substituted phenylazo) phenyl 4″-alkoxybenzoates (IIn_a-f) in which the two terminal (alkoxy- and X) groups are exchanged.     

Effect of lateral substitution on supramolecular liquid crystal associates induced by hydrogen-bonding interactions between 4-(4′-pyridylazo-3-methylphenyl)-4′′-alkoxy benzoates and 4-substituted benzoic acids

Five laterally methyl-substituted pyridine-based derivatives of the title compounds (I 8–I 16), with molecular formula 4-C_nH_2n+1O-C₆H₄COOC₆H₃(3-CH₃)-N=N-C₅H₄N were prepared and their molecular formulae elucidated via elemental analyses, infrared, nuclear magnetic resonance and mass spectra. The number of carbon atoms in the alkoxy chain (n) varies between 8, 10, 12, 14, and 16 carbons. The newly prepared pyridine-based derivatives were investigated for their mesophase behaviour by differential scanning calorimetry and polarised optical microscopy; most of them were found to possess monotropic smectic C (SmC) mesophase. Two groups (A and B) of the 1:1 hydrogen-bonded associates, formed between each of the derivatives I 8– I 16 and two types of 4-substituted benzoic acids (II), were prepared and similarly characterised to investigate the effect of lateral methyl substitution on the central phenylene ring, as well as terminal polar substituents and alkoxy-chain length on the stability of the mesophases induced by intermolecular hydrogen bonding. In Group A complexes, mesomorphic 4-alkoxy benzoic acids, that carry the terminal n-alkoxy group of varying chain length, were used. The other series of complexes (Group B) is composed from the same pyridine-based derivatives and each of the non-mesomorphic 4-substituted benzoic acids that carries small compact polar groups, varying between CH₃O, CH₃, H, Cl, Br, and CN. All complexes prepared were investigated for their mesophase behaviour by differential scanning calorimetry and polarised optical microscopy and found to be purely smectogenic, possessing SmC as the only mesophase observed. The formation of the hydrogen-bonded complexes was confirmed by constructing their binary phase diagrams, which cover the whole range of concentration of the two complements.