Chiral separation of 1,1'-bi-2-naphthol and its analogue on molecular imprinting monolithic columns by HPLC

Two molecular imprinting polymer (MIP) monolithic columns with (S)-(-)-1,1'-bi-2-naphthol and (R)-(+)-5,5',6,6',7,7',8,8'-octahydro-1,1'-bi-2-naphthol as the templating molecules, respectively, have been prepared by in situ polymerization using 4-vinylpyridine and ethylene dimethacrylate as functional monomer and cross-linker, respectively. The columns with good flow-through properties were obtained by changing the molar ratio of the functional monomer and the template molecule. The effects of mobile-phase composition on separation of enantiomers were systematically investigated. The results indicate that hydrophobic interaction in aqueous solution and hydrogen-bonding interaction in ACN between the enantiomers and polymers could play important roles in the retention and resolution. The effects of chromatographic conditions, such as flow rate, column temperature, sample loading, on the enantioseparation were also studied. Further, these two MIP columns show a cross-reactivity.     

Anticancer activity of novel 3-azaxanthenes

Novel 3-azaxanthenes have been synthesized via acid-catalyzed one-pot Friedel–Crafts reaction of pyridoxal/pyridoxal-5'-phosphate with naphthols followed by dehydration of the intermediate bis(2-hydroxyaryl)-(pyridin-4-yl)methane derivatives. The cytotoxicity of the obtained 3-azaxanthenes against M-HeLa and HuTu-80 tumor cell lines is comparable to that of tamoxifen, whereas the cytotoxicity against normal cell line is absent in the tested concentrations range, which makes this class of compounds interesting for further studies.     

Two validated chromatographic determinations of an antifungal drug,its toxic impurities and degradation product: A comparative study

Tolnaftate, a thionoester anti‐fungal drug, was subjected to alkaline hydrolysis to produce methyl(m‐tolyl)carbamic acid and β ‐naphthol (tolnaftate impurity A). N‐Methyl‐m‐toluidine, tolnaftate impurity D, was synthesized and structurally elucidated along with tolnaftate alkaline degradation products using IR, H¹NMR and MS. Two stability‐indicating HPTLC and RP‐HPLC methods were developed and validated, for the first time, for determination of tolnaftate, its alkaline degradation products and toxic impurities in the presence of methyl paraben, as a preservative in Tinea Cure^® cream. The proposed HPTLC method depended on separation of the studied components on TLC silica gel F₂₅₄ plates using hexane–glacial acetic acid (8:2, v/v) as a developing system and scanning wavelength of 230 nm. The proposed RP‐HPLC method was based on separation of the five components on an Eclipse plus C₁₈ column. The mobile phase used was acetonitrile–water containing 1% ammonium formate (40:60, v/v), with a flow rate of 1 mL/min and detection wavelength of 230 nm. The proposed methods allowed the assay of tolnaftate toxic impurities, β ‐naphthol and N‐methyl‐m‐toluidine, down to 2%, allowing tracing of β ‐naphthol that could be absorbed by the skin causing systemic toxic effects, unlike tolnaftate, indicating the high significance of such determination. International Conference on Harmonization guidelines were followed for validation.     

Synthesis,characterization and application of 3‐methyl‐1‐sulfonic acid imidazolium tetrachloroferrate as nanostructured catalyst for the tandem reaction of β‐naphthol with aromatic aldehydes and amide derivatives

3‐methyl‐1‐sulfonic acid imidazolium tetrachloroferrate {[Msim]FeCl₄} was prepared and fully characterized by fourier transform infrared spectroscopy (FT‐IR), X‐ray diffraction (XRD), thermal gravimetric analysis (TGA), differential thermal gravimetric (DTG), field emission scanning electron microscopy (FESEM), energy dispersive X‐ray analysis (EDX) and vibrating sample magnetometer (VSM) and used, as an efficient catalyst, for the tandem reaction of β‐naphthol with aromatic aldehydes and benzamide at 110 °C under solvent‐free conditions to give 1‐amidoalkyl‐2‐naphthols in high yields and very short reaction times.     

壳聚糖/乙炔黑修饰电极上萘酚异构体的电化学行为及同时测定

制备了壳聚糖/乙炔黑复合修饰电极(CS-AB/GCE),采用SEM和交流阻抗法对其进行表征。并利用循环伏安法(CV)研究了萘酚异构体(α-N和β-N)在该修饰电极上的电化学行为,对实验条件进行了优化。结果表明,在p H 7.0的PBS缓冲液中,α-N和β-N在该修饰电极上均出现一不可逆氧化峰,且在20~200m V/s范围内,其峰电流与扫速呈线性关系,表明电极过程是受吸附控制的不可逆过程。计算了电极过程的部分动力学参数,优化了差分脉冲伏安法(DPV)的实验参数,并对α-N和β-N进行同时测定,发现二者的微分氧化峰电流值与其浓度在2.5×10-6~1.0×10-4mol/L范围内呈良好的线性关系(rα-N=0.996;rβ-N=0.998)。α-N和β-N的检出限(S/N=3)分别为3.4×10-7mol/L和2.4×10-7mol/L。采用该法对实际水样进行检测,得到α-N和β-N的加标回收率分别为96.7%~105.1%和98.8%~103.9%。     

Syntheses and gas transport properties of polyarylates based on isophthalic and terephthalic acids and mixtures of bisphenol A and 1, 1 bi‐2‐naphthol

Polyarylates based on isophthalic (IA) and terephthalic (TA) acids and an equimolar mixture of the diols Bisphenol A (BPA) and 1,1 bi‐2‐naphthol (BN) were synthesized to produce BPA‐BN/IA and BPA‐BN/TA polymers and to measure their gas permeability coefficients, P(i), at several pressures and 35 °C, to the gases O₂, N₂, CH₄, and CO₂. For the BPA‐BN/IA membranes, at a 2 atm up‐stream pressure, the P(O₂) and P(CO₂) are 0.93 and 4.0 Barrers with O₂/N₂ and CO₂/CH₄ ideal separation factors of 6.7 and 27. For the BPA‐BN/TA, at a 2 atm up‐stream pressure, the P(O₂) and P(CO₂) are 2.0 and 9.9 Barrers with O₂/N₂ and CO₂/CH₄ ideal separation factors of 5.6 and 21. Comparing the selectivity–permeability balance of properties shown by the BPA/TA membranes with that shown by the copolymer BPA‐BN/TA, the balance moves in the direction of higher selectivity and lower permeability because of the incorporation of BN, which is a more rigid monomer than BPA. However, when the balance of properties for the pair O₂/N₂ shown by BPA‐BN/TA is compared with the one shown by other membranes such as those based on mixtures of diols and diacids, that is the bisphenol A‐naphthalene/I‐T polymers reported in the literature, the balance moves up and to the right of the typical selectivity–permeability trade‐off observed in the BPA‐polyarylate family. Thus, simultaneous incorporations of flexible and rigid monomers in both the diols and the diacids lead to more productive and more selective membranes. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 256–263, 2006     

Iridium‐Catalyzed Intermolecular Asymmetric Dearomatization of β‐Naphthols with Allyl Alcohols or Allyl Ethers

An Ir‐catalyzed intermolecular asymmetric dearomatization reaction of β‐naphthols with allyl alcohols or allyl ethers was developed. When an iridium catalyst generated from [Ir(COD)Cl]₂ (COD=cyclooctadiene) and a chiral P/olefin ligand is employed, highly functionalized β‐naphthalenone compounds bearing an all‐carbon‐substituted quaternary chiral center were obtained in up to 92 % yield and 98 % ee . The direct utilization of allyl alcohols as electrophiles represents an improvement from the viewpoint of atom economy. Allyl ethers were found to undergo asymmetric allylic substitution reaction under Ir catalysis for the first time. The diverse transformations of the dearomatized product to various motifs render this method attractive.     

Hafnium(Ⅳ) bis(perfluorooctanesulfonyl)imide complex catalyzed direct amidomethylation for the synthesis of 1-(arylamido)-methyl-2-naphthols in fluorous medium

Hafnium(Ⅳ) bis(perfluorooctanesulfonyl)imide complex is found to be an efficient catalyst for the multicomponent condensation ofβ-naphthol,aromatic aldehydes and urea or amides in perfluorodecalin to afford the corresponding substituted amidomethyl naphthols in good yields.The remarkable features of this new procedure are high yields,shorter reaction times, reusability of catalyst and simple work-up procedures.     

A modified reaction for the preparation of amidoalkyl naphthols

An efficient synthesis of amidoalkyl naphthols using FeCl₃·SiO₂ as a heterogeneous catalyst is described. This thermal solvent-free procedure offers advantages such as shorter reaction times, simple work-up, excellent yields, and recovery and reusability of the catalyst.