NMR spectroscopic characterization of inclusion complexes of hydroxy-substituted naphthalenes with native and modified β-cyclodextrins

The equilibrium constants (K) for the inclusion complexation of three kinds of β-cyclodextrins (β-CDs: native β-CD, heptakis(2,6-di-O-methyl)-β-CD, and 6-O-α-d-glucosyl-β-CD) with OH-substituted naphthalenes (2-naphthol, 2,3-dihydroxynaphthalene, and 2,6-dihydroxynaphthalene) were determined from the induced chemical shifts of NMR measurements for inclusion complexes: K = 188–1,250 mol^?1 dm³. The modified β-CDs form stable 1:1 inclusion complexes with OH-substituted naphthalenes, and the high stability of inclusion complexes of 2,6-dihydroxynaphthalene having a hydrophobic body and hydrophilic ends is shown. In addition, the structures of inclusion complexes were characterized by 2D ROESY NMR measurements. The differences in the structure of the inclusion complexes were observed for three kinds of naphthol guest molecules. Based on the results, the inclusion abilities enhanced by methylation of the OH groups at the CD rim or the side chain of branched β-CD are discussed.     

Kinetic and Spectroscopic Characterization of 1-Naphthol 2-hydroxylase from Pseudomonas sp. Strain C5

1-Naphthol 2-hydroxylase (1-NH) catalyzes the conversion of 1-naphthol to 1,2-dihydroxynaphthalene. 1-NH from carbaryl degrading Pseudomonas strain C5 was purified and characterized for its kinetic and spectroscopic properties. The enzyme was found to be NAD(P)H-dependent external flavin monooxygenase. Though the kinetic parameters of 1-NH from strain C5 appear to be similar to 1-NH enzyme from strains C4 and C6, however, they differ in their N-terminal sequences, mole content of flavin adenine dinucleotide (FAD), reconstitution of apoenzyme, and K _i. 1-NH showed narrow substrate specificity with comparable hydroxylation efficiency on 1-naphthol and 5-amino 1-naphthol (~30 %) followed by 4-chloro 1-naphthol (~9 %). Salicylate was found to be the nonsubstrate effector. The flavin fluorescence of 1-NH was found to increase in the presence of 1-naphthol (K _d?=?11.3 μM) and salicylate (K _d?=?1027 μM). The circular dichroism (CD) spectra showed significant perturbations in the presence of NAD(P)H, whereas no changes were observed in the presence of 1-naphthol. Naphthalene, 1-chloronaphthalene, 2-napthol, and 2-naphthoic acid were found to be the mixed inhibitors. Chemical modification studies showed the probable involvement of His, Cys, and Tyr in the binding of 1-naphthol, whereas Trp was found to be involved in the binding of NAD(P)H.     

Synthesis of fused α-methylene-γ-butyrolactone derivatives through pyridine-induced addition of phenols to dimethyl acetylenedicarboxylate

The reaction between dimethyl acetylenedicarboxylate and various phenols including phenol, 1-naphthol, 2-naphthol, 8-hydroxyquinoline, 1,6-dihydroxynaphthalene, cathechol, hydroquinone and resorcinol in the presence of catalytic amounts of pyridine leads to fused α-methylene-γ-butyrolactone derivatives in good yields.     

Test determination of aniline in solutions based on azo coupling with analytical reagents incorporated into silicic acid xerogels

Silicic acid xerogels modified with 1-naphthol, 2-naphthol, 8-hydroxyquinoline, 2,7-dihydroxynaphthalene,N-(l-napthyl)ethylenediamine andp-hydroxydiphenyl were synthesized. It was shown that the immobilized reagents can participate in reactions of azo coupling with products of aniline diazotization. The best (among the studied) immobilized reagent for determining aniline was 1-naphthol. Xerogel modified with 1-naphthol was used for determining aniline in solutions by solid-phase spectrophotometry and with visual detection. The analytical ranges for aniline at the optimal conditions were 0.005-10 mg/L using solid-phase spectrophotometry and 0.05-15 ng/L with visual detection. The results were verified in the analysis of synthetic mixtures.     

The oxidative coupling of indole with some phenolic compounds,naphthols and catechols

The oxidative coupling of indole with three naphthols, 2-naphthol, 2,3-dihydroxynaphthalene and 2,7-dihydroxynaphthalene gave 1,1-bis(3′-indolyl)-2(1H)naphthalenone, 1,1-bis(3′-indolyl)-3-hydroxy-2(1H)naphthalenone and 1,1-bis(3′-indolyl)-7-hydroxy-2(1H)naphthalenone, respectively. The coupling of indole with protocatechuic aldehyde gave bis-(3-indolyl)-(3′,4′-di-hydroxyphenyl)methane and that of indole with homocatechol gave 3-(2′-methyl-3′,4′-di-hydroxyphenyl)indole.     

Comparison of Separation Performances of Cellulose-Based Chiral Stationary Phases in LC Enantioseparation of Aminonaphthol Analogues

The enantiomers of 1-(α-aminoarylmethyl)-2-naphthol, 1-(α-aminoalkyl)-2-naphthol and 2-(α-aminoarylmethyl)-1-naphthol analogues were separated on tris(3,5-dimethylphenyl)carbamoyl cellulose-based CelluCoat and Chiralcel OD-H chiral stationary phases, with n-heptane/alcohol or n-hexane/alcohol as mobile phase. The experimental data are utilised to discuss the effects of the mobile phase composition, the nature of the alcoholic modifier and the specific structural features of the analytes (1- or 2-naphthol analogues with aryl or alkyl substituents) on the retention and separation. The separation performances of CelluCoat and Chiralcel OD-H columns were compared. Due to its high resolution ability and its effectivity, CelluCoat proved to be a good choice for the enantiomeric separation of aminonaphthol analogues.     

Determination of six aromatic compounds by using target factor analysis-UV spectrometry

The UV-spectra solutions containing mixtures of 1-naphthylamine(NAA), 1-naphthol(NAP), 2,7-dihydroxynaphthalene(DHN), 2,4-dimethoxybenzaldehyde(DMO), methyl salicylate(MSA) and dibutyl phthalate (DBP), have been measured. The numbers, identities and concentrations of the aromatic compounds in the mixtures have been determined successfully using Target Factor Analysis. Some sample mixtures have been analyzed successfully. The average recoveries are 99% for NAP, 102% for NAA, 102% for DHN, 103% for DMO, 102% for MSA, 101% for DBP.     

Solid state reaction between α-naphthol and p-benzoquinone

The solid state reaction between α-naphthol and p-benzoquinone yields a red crystalline 1 : 1 adduct; in very concentrated solutions the red color can be seen, but it may be due either to Mulliken charge transfer or hydrogen bonding interactions. Kinetic studies of the solid state reaction by a capillary technique indicate that p-benzoquinone is the diffusing species, and that either surface migration or vaporphase diffusion plays an important role in the rate of complex formation. Microscopic examination of a single crystal of α-naphthol in the presence of p-benzoquinone vapor suggests that the reaction occurs only at defect centers on the α-naphthol surface. Since the reaction in the solid state goes to completion, it is suggested that cracks and crevices are formed, through which p-benzoquinone can diffuse easily into the lattice of the complex.     

Simple access to pentacyclic oxazinoisoquinolines via an unexpected transformation of aminomethylnaphthols

Unexpected reactions between 1-α-aminobenzyl-2-naphthol, 1-aminomethyl-2-naphthol, N-benzyl-1-α-aminobenzyl-2-naphthol and 6,7-dimethoxy-3,4-dihydroisoquinoline to furnish naphth[1,2-e][1,3]oxazino[2,3-a]isoquinolines are reported. The reaction conditions involved classical heating at 80 °C in MeCN for 22 h (57-62%), or the use of microwave conditions (100 °C), which allowed a reduction of the reaction time to 90 min and resulted in somewhat higher yields (73-82%).     

Photo-Fries rearrangement of 2-Naphthylbenzoate

Photo-Fries rearrangement of 2-Naphthylbenzoate gives 6-benzoyl-2-naphthol and 8-benzoyl-2-naphthol in addition to the expected product, 1-benzoyl-2-naphthol.     

Synthesis of enantiomeric 4-hydroxypropranolols from 1,4-dihydroxynaphthalene

Both (R)- and (S)-enantiomers of 4-hydroxypropranolol were effectively prepared from 1,4-dihydroxynaphthalene in eight steps. The overall yields were around 30%.     

Ultraviolet absorption spectra of α-nitroso β-naphthol and its copper chelate

From a comparative study of the U.V. absorption spectra of α-nitroso-β-naphthol and of β-naphthol in neutral ethanol and in the presence of 0.1N HClO₄ and 0.1N KOH respectively, evidence in favour of the quinone-oxime structure of α-nitroso-β-naphthol has been presented. The spectrum of the copper chelate of α-nitroso-β-naphthol indicates a planar configuration of the complex with considerable resonance between the quinonoid and benzenoid structures of the ligand.     

Synthesis and conformational analysis of new naphth[1,2-e][1,3]oxazino[3,4-c]quinazoline derivatives

A new highly functionalized aminonaphthol derivative, 1-(amino(2-aminophenyl)methyl)-2-naphthol (4), was synthesized by the reaction of 2-naphthol, 2-nitrobenzaldehyde and tert-butyl carbamate or benzyl carbamate, followed by reduction and/or removal of the protecting group. The aminonaphthol derivative thus obtained was converted in ring-closure reactions with formaldehyde, benzaldehyde and/or phosgene to the corresponding naphth[1,2-e][1,3]oxazino[3,4-c]quinazoline derivatives. The conformational analysis of some derivatives by NMR spectroscopy and accompanying molecular modelling are also reported.     

Adsorption and adsolubilization of surfactants on titanium dioxides with functional groups

Adsorption of ionic surfactants on titanium dioxide with dodecyl chain groups or quaternary ammonium groups (XNm, where m is the carbon number of the alkyl chain, 4–16) was investigated. The adsorbed amount of cationic surfactants (dodecyltrimethylammonium bromide, DTAB; 1,2-bis(dodecyldimethylammonio)ethane dibromide, 2RenQ) on titanium dioxide with dodecyl chain groups increased with increasing concentration of the dodecyl chain due to hydrophobic interaction, where the adsorbed amounts of DTAB at saturation was considerably greater than those of 2RenQ. Adsorption of an anionic surfactant (sodium dodecyl sulfate, SDS) on XNm occurred mainly due to both electrostatic attraction force and hydrophobic interaction, depending on the alkyl chain length on XNm. On the other hand, adsorption of cationic surfactants, DTAC and 2RenQCl (their counter ions are chloride ions), on XNm was quite smaller compared with that of SDS due to electrostatic repulsion force. Adsolubilization of 2-naphthol in the surfactant-adsorbed layer on the titanium dioxides with the functional groups was also studied. The adsolubilized amounts of 2-naphthol on titanium dioxide with dodecyl chain groups were enhanced by adsorption of DTAB, but no distinct increase in the adsolubilization was observed by adsorption of 2RenQ. In the case of XNm, the amount of 2-naphthol adsorbed in the absence of surfactants increased with increasing alkyl chain length on XNm. Further, an appreciable increase in the adsolubilization of 2-naphthol on XNm with adsorption of 2RenQCl was observed. It was found from the admicellar partitioning coefficients that the adsolubilization of 2-naphthol preferably occurs on XNm by adsorption of SDS or 2RenQCl compared with that by DTAC. These differences in the adsolubilization were discussed by microproperties of the surfactant-adsorbed layers estimated using a spin probe.     

Catalytic alkylation of 2-naphthol with C1−C3 alcohols

The vapour phase alkylation of 2-naphthol with C₁?C₃ alcohols in the presence of an iron catalyst that contains Cr-, Si- and K-oxides was investigated. 2-Naphthol was methylated in a temperature range 520–645 K giving first 1-methyl-2-naphthol and then 1,3-dimethyl-2-naphthol with total selectivity of ortho-alkylation over 98%. In the cases of ethanol and n-propanol, derivatives of 2-naphthol alkylated in the 1-position were obtained with high yield and selectivity. The reactions were carried out in a continuous process at atmospheric pressure.     

The heterometric micro-analysis of cobalt with α-nitroso - β-naphthol. a general study.

1. The reaction between cobaltous or cobaltic and α-nitroso-β-naphthol was extensively studied heterometrically both in water and in alcoholic solutions. The influence of complexing agents and of the acidity on the precipitation of cobalt-α-nitroso-β-naphthol was investigated. In all cases the molar ratios : [Co] [αβ] at the end of the precipitation were established and the possible compounds which were obtained were discussed. 2. Micro-analytical heterometric methods are given for the determination of cobalt or α-nitroso-β-naphthol. The determination can be carried out with precision even in concentrations as low as 0.0001M Co. Conversely, very dilute alcoholic solutions of α-nitroso-β-naphthol may be titrated with precision with a dilute solution of cobalt nitrate. 0.2–0.5 mg cobalt in 20 ml solution are required for the analysis. The error lies between zero and 3%.     

Dual activation in oxidative coupling of 2-naphthols catalyzed by chiral dinuclear vanadium complexes

An efficient enantioselective oxidative coupling of 2-naphthol derivatives based on a concept of dual activation catalysis is realized. A chiral dinuclear vanadium(IV) complex (R_a,S,S)-1e possessing (S)-tert-leucine moieties at the 3,3′-positions of the (R)-binaphthyl skeleton was developed, which was found to promote the oxidative coupling of 2-naphthol to afford (S)-BINOL with 91% ee. To verify the dual activation mechanism, mononuclear vanadium(IV) complex (S)-8 was also prepared. Kinetic analysis revealed that the reaction rate of oxidative coupling of 2-naphthol promoted by (R_a,S,S)-1e is 48.3 times faster than that of (S)-8. The two vanadium metals in the chiral complex activate two molecules of 2-naphthol simultaneously in an intramolecular manner coupling reaction, achieving a high reaction rate with high enantiocontrol. Reaction mechanisms of the oxidative coupling reaction promoted by either vanadium(IV) or vanadium(V) complexes are also described.     

Acceleration of solid state Diels-Alder reactions by incorporating the reactants into crystalline charge transfer complexes

Diels-Alder reactions in a solid state between anthracene (AN) derivatives and p-benzoquinone (BQ) under mechanical stressing are accelerated by adding a catalytic amount of 2-naphthol (NP) or (rac)-1,1′-bis-2-naphthol (BN). Their catalytic effects are based on the formation of the charge transfer complex with strong hydrogen bonds. BN is capable of incorporating BQ together with its reaction partner, AN derivatives, simultaneously. The resulted molecular complex with BN provides crystallographically ordered homogenic reaction fields, resulting in the higher rates of the present solid state Diels-Alder reaction.     

Investigations on stabilities and intermolecular interactions of different naphthalene derivatives dimers by using B3LYP and M06-2X density functional calculations

In this paper, the stabilities and hydrogen bond interactions of 4-chloro-1-naphthol, 1-hydrox-ynaphthalene and 1,4-dihydroxynaphthalene dimers have been theoretically investigated by means of study on binding energies with nonlocal hybrid three-parameter Lee-Yang-Parr, B3LYP, and M06-class functional calculations. Calculations on dimers aim to provide as a test of the efficacy of M06 calculations for intermolecular interaction calculations and more strongly bound systems. For hydroxyl- and halo-substituted derivatives of naphthalene, total electronic energies, their correction for the zero point vibrational energies with some calculated thermodynamic properties and their relative differences are together in order to discuss the rotamer structures. Static (hyper) polarizabilities and the electric dipole moments, frontier molecular orbital energy gaps and the relationships between them have been interpreted. Generally, they are seen that the calculated geometric parameters and spectral results were in a good agreement with the corresponding experimental data.     

Regioselective oxidative polymerization of 1,5-dihydroxynaphthalene catalyzed by bilirubin oxidase in a water–organic solvent mixed solution

Bilirubin oxidase (EC1.11.1.7) was used to catalyze the oxidative polymerization of 1,5-dihydroxynaphthalene to its polymer in a mixed solvent composed of dioxane, ethyl acetate, and acetate buffer. In an aqueous solution, the enzymatic oxidative polymerization hardly occurred and resulted in negligible yield mainly due to the poor solubility of 1,5-dihydroxynaphthalene. In the mixed solvent the conversion proceeded with a yield of ca. 70%. The polymer yield was studied with respect to reaction time and solvent components. Elemental analysis, UV-visible, fluorescent, and FT-IR spectroscopic analyses, proton NMR and electrochemical studies, and solubility in various organic solvents revealed that 1,5-dihydroxynaphthalene is polymerized by the C? C coupling. The molecular weight of the polymeric products solubilized with DMF varied from low molecular weight product to high molecular weight polymer. From the chromatographic studies, the organic solvent–insoluble residue was suggested to be highly polymerized material. Based on these findings a possible mechanism for enzymatic polymerization of 1,5-dihydroxynaphthalene is presented: less stable intermediates produced enzymatically from 1,5-dihydroxynaphthalene undergo coupling and polymerization to ortho-1,5-dihydroxynaphthalene polymer, thereby resulting in a regioselective polymerization of 1,5-dihydroxynaphthalene. © 1993 John Wiley & Sons, Inc.