Origins of selectivity in a colorimetric charge-transfer sensor for diols

Bispyridyl hydrogen bonding receptor 1 forms colored charge transfer (CT) complexes with complementary phenols and naphthols. Despite its low association constants of approximately 10(1) M(-1), receptor 1 was highly selective forming CT complexes of varying color and intensity with different diol guests. The selectivity of 1 was correlated with the ability of its CT band to simultaneously yield information about the association constant and the electronic structure of the phenols and naphthols.     

A One-Pot Approach for Bio-Based Arylamines via a Combined Photooxidative Dearomatization-Rearomatization Strategy

The synthesis of arylamines from renewable resources under mild reaction conditions is highly desired for the sustainability of the chemical industry, where the production of hazardous waste is a prime concern. However, to date, there are very few tools in chemists’ toolboxes that are able to produce arylamines in a sustainable manner. Herein, a robust one-pot approach for constructing bio-based arylamines via a combined photooxidative dearomatization-rearomatization strategy is presented. The developed methodology enables the synthesis of structurally complex amines in moderate-to-good isolated yields using biomass-derived phenols, natural α-amino acids, and naphthols under remarkably mild reaction conditions. For the photooxygenation of phenols, a novel chrysazine-based catalyst system was introduced, demonstrating its efficiency for the synthesis of natural products – hallerone, rengyolone, and the pharmaceutically relevant prodrug DHED.     

Molecular complexes ofsym-octahydro-1-chalcogenaanthracene salts with aromatic compounds

Complexes ofsym-octahydro-10-chalogenaanthracene perchlorates with aromatic hydrocarbons, di- and triatomic phenols, naphthols, and aromatic amines can be readily separated in the solid state. Complex formation is clearly shown to lower the oxidative power of the heteroaromatic cations.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 27–32, January, 1995.Deceased     

Nitrosation of Phenolic Substrates under Mildly Basic Conditions: Selective Preparation of p-Quinone Monooximes and Their Antiviral Activities

Nitrosation of 3-methoxyphenol and 1-naphthol were examined under both acidic (NaNO(2)-EtCO(2)H-H(2)O) and basic (i-AmNO(2)-K(2)CO(3)-DMF) conditions. Acidic nitrosations afforded ortho-directed products, whereas para-directed nitrosations were observed under basic conditions to yield p-quinone monooximes. The basic para-directed nitrosation was further examined using 15 phenols, two naphthols, and four phenolic heterocyclics. A one-pot operation of the basic nitrosation followed by methylation with dimethyl sulfate gave the corresponding methyl ethers in high yield. Two p-quinone monooximes derived from 3-methoxyphenol and 8-hydroxyquinoline showed a moderate activity against HSV-1, and the latter oxime was also effective against HSV-2. On the other hand, p-quinone monooximes derived from methyl salicylate, 1-naphthol, 7-hydroxy-2-methylbenzo[b]furan, and 8-hydroxycoumarin showed the comparable activity to that of DDI against HIV-1.     

Redox‐Neutral α,β‐Difunctionalization of Cyclic Amines

In contrast to the continuously growing number of methods that allow for the efficient α‐functionalization of amines, few strategies exist that enable the direct functionalization of amines in the β‐position. A general redox‐neutral strategy is outlined for amine β‐functionalization and α,β‐difunctionalization that utilizes enamines generated in situ. This concept is demonstrated in the context of preparing polycyclic N,O‐acetals from simple 1‐(aminomethyl)‐β‐naphthols and 2‐(aminomethyl)‐phenols.     

Mild and Selective Nitration of Phenols by Zeofen

Certain phenols and naphthols were nitrated regioselectively with zeofen in dichloromethane as solvent at room temperature and in a short reaction time to give good yields.     

Squaramide‐Catalyzed Asymmetric aza‐Friedel–Crafts/N,O‐Acetalization Domino Reactions Between 2‐Naphthols and Pyrazolinone Ketimines

N‐Boc ketimines derived from pyrazolin‐5‐ones were explored to develop an unprecedented domino aza‐Friedel–Crafts/N,O‐acetalization reaction with 2‐naphthols. The novel method requires a catalyst loading of only 0.5 mol % of a bifunctional squaramide catalyst, is scalable to gram amounts, and provides a new series of furanonaphthopyrazolidinone derivatives bearing two vicinal tetra‐substituted stereogenic centers in excellent yields (95–98 %) and stereoselectivity (>99:1 d.r. and 97–98 % ee ). A different reactivity was observed in the case of 1‐naphthols and other electron‐rich phenols, which led to the aza‐Friedel–Crafts adducts in 70–98 % yield and 47–98 % ee .     

Synthesis of tricyclic and tetracyclic sultones by Pd-catalyzed intramolecular cyclization

A new efficient synthesis of aromatic six-membered ring sultones by the implementation of ligand-free Pd-catalyzed intramolecular cyclization of aromatic sulfonates derived from various bromo phenols and naphthols is described.     

One-step novel synthesis of methylene bisphenols and methylene bisnaphthols using Lewis acid mediated rearrangement

Mono- and di-substituted isomeric methylene bisphenols and methylene bisnaphthols have been synthesized by rearrangement of the corresponding O-methoxyacetyl derivatives of phenols and naphthols, respectively, in presence of aluminium chloride under dry conditions. The chemistry observed is different from the usual Fries rearrangement reaction and involves an intermolecular rearrangement. The reactions reported here also reflect the influence of substituents present in the substrate as is supported by the substitution of the bridging methylene at a position meta to the phenolic hydroxyl in some of the minor products formed along-side the majorly formed ortho substituted products.     

Electrochemical Organic Synthesis of Electron-Rich Biaryl Scaffolds: An Update

Biaryl scaffolds are widely spread in biologically important natural products, in numerous therapeutic agents, but they are also considered a privileged class of ligands and (organo)catalysts; therefore, the development of efficient alternative methodologies to prepare such compounds is always attracting much attention. The present review discusses the organic electrosynthesis of biaryls starting from phenols, anilines, naphthols, and naphthylamines. The most significant examples of the works reported in the last decade are presented and classified according to the single class of molecules: after the introduction, the first three sections relate to the reactions of phenols, naphthols, and anilines, respectively; the other two sections refer to cross-coupling and miscellaneous reactions.     

Efficient one-pot synthesis of benzopyranobenzopyrans and naphthopyranobenzopyrans by domino aldol-type reaction/hetero Diels-Alder reaction of resorcinols and naphthols

The efficient one-pot synthetic approaches for benzopyranobenzopyrans and naphthopyranobenzopyrans are described. The key strategies involve ethylenediamine diacetate-catalyzed cyclization by domino aldol-type reaction/hetero Diels-Alder reaction of resorcinols and naphthols to benzaldehydes with O-allyl ether groups. These reactions provide a rapid route for the synthesis of novel types of polyheterocycles with stereochemically defined quaternary carbon centers.     

Organocatalytic Asymmetric Addition of Naphthols and Electron‐Rich Phenols to Isatin‐Derived Ketimines: Highly Enantioselective Construction of Tetrasubstituted Stereocenters

A quinine‐derived thiourea organocatalyst promoted the highly enantioselective addition of naphthols and activated phenols to ketimines derived from isatins. The reaction afforded chiral 3‐amino‐2‐oxindoles with a quaternary stereocenter in high yields (up to 99 %) with excellent enantioselectivity (up to 99 % ee). To the best of our knowledge, this transformation is the first highly enantioselective addition of naphthols to ketimines.     

Tandem [4 + 1 + 1] annulation and metal-free aerobic oxidative aromatization: straightforward synthesis of highly substituted phenols from one aldehyde and two ketones

Polysubstituted phenols are efficiently assembled from one aldehyde and two different methyl ketones in a one-pot operation via a newly base-induced regiospecific [4 + 1 + 1] annulation and sequential metal-free oxidative aromatization using molecular oxygen (from air) as the sole oxidant at room temperature.     

Zn(NO_3)_2·6H_2O/2,4,6-trichloro-1,3,5-triazine(TCT) a mild and selective system for nitration of phenols

<正>Certain phenols and naphthols were nitrated regioselectively with Zn(NO_3)_2·6H_2O/TCT in acetonitrile as solvent at room temperature and short reaction time in good yields.The reaction condition was mild.TCT is a cheap and commercially available reagent.It performed as an acid catalyst in this transformation.     

Simultaneous stopped-flow determination of 1- and 2-naphthol

A kinetic method for the simultaneous determination of 1- and 2-naphthol based on their different rate of coupling with diazotized sulphanilic acid in a weakly acid medium is reported. The reaction is performed by a stopped-flow technique and monitored spectrophotometrically at 475 nm. On the basis of this reaction, mixtures of these naphthols can be determined by measuring the reaction rates at two reaction times which gave maximum discrimination between the two naphthols. Theoretical equations are used in order to evaluate the accuracy of the proposed method. Mixtures of these naphthols at the mug/ml level and in 2-naphthol/ 1 -naphthol ratios from 20:1 to 1:5 can be determined with a relative standard deviation of 1.5%. Ternary mixtures of carbaryl, 1-naphthol and 2-naphthol can also be resolved.     

A one-pot multicomponent reaction for synthesis of 1-amidoalkyl-2-naphthols catalyzed by PEG-based dicationic acidic ionic liquids under solvent-free conditions

Abstract  

A mild and efficient method was developed for preparation of amidoalkyl naphthols via one-pot three-component condensation of aldehydes with amides and 2-naphthol in the presence of polyethylene glycol (PEG)-based dicationic acidic ionic liquid as a powerful catalyst under solvent-free conditions. Excellent yields, short reaction time, simple work-up, and reusable catalyst are advantages of this procedure.     

A Transition‐Metal‐Free Synthesis of Fluorinated Naphthols

Herein, we describe a transition‐metal‐free protocol for the conversion of simple 2‐allyl‐3‐(trifluoromethyl)phenols into substituted 5‐fluoronaphthalen‐1‐ols. The key events of this reaction include the selective activation of two C?F bonds and formation of an intermediate hexatriene system, which undergoes a 6π electrocyclization, followed by rearomatization. This concept enables the rapid conversion (three steps) of various commercially available 3‐(trifluoromethyl)phenols into novel fluorine‐containing naphthols, which are difficult to prepare by previous methods. The reported sequence was also extended to a one‐pot transformation of 3‐(trifluoromethyl)phenols into 5‐fluoronaphthalen‐1‐ols.     

Ni/Silica catalyzed acetylation of phenols and naphthols: An eco-friendly approach

A method for 10% Ni/SiO₂ catalyst is developed for acetylation of phenol, substituted phenols, naphthols, substituted alcohols under mild liquid phase conditions affording aromatic esters with maximum conversions of 50–80% and 100% selectivity. The catalyst showed remarkable reusability for up to 4 cycles. This methodology is eco-friendly, economic with Ni/SiO₂ catalysts exhibiting no loss of activity the first report for acetylation of substituted phenols to esters with 10% Ni/SiO₂ catalyst.     

Dismutation of arylene phosphorodiamidites: Specific features and aspects of preparative use

The dismutation of arylene phosphorodiamidites derived from the simplest phenols and naphthols and of their dibasic analogs was studied. The main regular trends of this process and the limits of its synthetic applicability were determined.     

Infrared Chemical Sensor for Detection of Chlorinated Phenols in Aqueous Solutions Based on a ATR Waveguide Coated with Structural Designed Polymers

A combination of solid phase micro‐extraction (SPME) with attenuated total reflection (ATR) infrared spectrometry provides a fast and sensitive way to detect organic compounds in aqueous solutions. It is especially useful for detection of chlorinated organic compounds in environmental samples. Currently, analyses of organic compounds in aqueous solutions are limited to low‐polarity compounds by the SPME/ATR‐IR sensing method. This limitation was mainly caused by the low polarity nature of the SPME phase. To increase the capability of this method to detect more polar compounds and also to increase the sensitivity in detection of organic compounds, the principle of “like‐dissolve‐like” was used to design a specific SPME phase for a certain class of chlorinated compounds. To demonstrate this concept, chlorinated phenols were used as probe molecules and polyvinyl chloride was chemically modified with phenol, ‐naphthol and ‐naphthol to provide SPME phases with a similar chemical structure to chlorinated phenols. These polymers were used as SPME phases and their performance were compared with the commonly used SPME phases (i.e., polystyrene and polyisobutylene). Results indicated that naphthols attached to PVCs provided much lower compactness, which allows fast speed in absorption of phenols. Meanwhile, due to the structural similarity between naphthols attached to PVCs and phenols, much higher partition coefficients were found for these chemically modified PVCs than conventionally used polymers. To further increase the sensitivity for analysis of chlorinated phenols, the common influencing factors, such as pH values and salt effect were also investigated. Apparently, pH values of the solutions did not influence the structure of the modified PVCs significantly. In absorption of chlorinated phenols in aqueous solutions with different pH values, the observed IR signals were decreased greatly in pH higher than 6 due to the charged form of chlorinated phenols that were presented. Results of the salt effect indicated that three times stronger of IR signals can be obtained if 20% (w/vol) of NaCl was added.