Clean and Convenient One-Pot Synthesis of 4-Hydroxycoumarin and 4-Hydroxy-2-quinolinone Derivatives

A simple, efficient, and environmentally friendly procedure has been developed for the reaction of Meldrum's acid with phenol, substituted phenols, aniline, or substituted anilines with Eaton's reagent (phosphoric anhydride + methylsulfonic acid) as cyclization reagent. 4-Hydroxycoumarins and 4-hydroxy-2-quinolinones were synthesized in moderate yields by carrying out the reaction in solvent-free, convenient, and clean one-pot preparation.     

Characterization of two hydroxytrichloropicolinic acids: application of the one-bond chlorine-isotope effect in 13C NMR

The structures of 4-hydroxy-3,5,6-trichloropyridine-2-carboxylic acid (1a) and 6-hydroxy-3,4,5-trichloro-2-carboxylic acid (1b) were verified by the NMR analysis of their corresponding methylated and decarboxylated derivatives 2,3,5-trichloro-4-methoxypyridine (5) and 3,4,5-trichloro-2-methoxypyridine (8), respectively. The 6-hydroxy isomer (1a) was found to be in equilibrium with its pyridinone tautomer as evidenced by the formation of significant amounts of 3,4,5-trichloro-1-methyl-6-oxo-1,6-dihydropyridine-2-carboxylic acid methyl ester (6b) on exhaustive methylation. The one-bond chlorine-isotope effect was used and shown to be an effective tool for the identification of chlorinated carbons in (13)C NMR spectra providing an additional tool for solving structural problems in chlorinated compounds.     

pH at the micellar interface: synthesis of pH probes derived from salicylic acid, acid-base dissociation in sodium dodecyl sulfate micelles, and Poisson-Boltzmann simulation

The study of the H+ concentration at the micellar interface is a convenient system for modeling the distribution of H+ at interfaces. We have synthesized salicylic acid derivatives to analyze the proton dissociation of both the carboxylic and phenol groups of the probes, determining spectrophotometrically the apparent pK(a)'s (pK(ap)) in sodium dodecyl sulfate, SDS, micelles with and without added salt. The synthesized probes were 2-hydroxy-5-(2-trimethylammoniumacetyl)benzoate; 2-hydroxy-5-(2-dimethylhexadecylammoniumacetyl)benzoate; 2-hydroxy-5-(2-dimethylhexadecylammoniumhexanoyl)benzoate; 2-hydroxy-5-(2-dimethylhexadecylammoniumundecanoyl)benzoate; 2-hydroxy-5-acetylbenzoic acid; and 2-hydroxy-5-dodecanoylbenzoic acid. Upon incorporation into SDS micelles the pK(ap)'s of both carboxylic and phenol groups increased by ca. 3 pH units and NaCl addition caused a decrease in the probe-incorporated pK(ap). The experimental results were fitted with a cell model Poisson-Boltzmann (P-B) equation taking in consideration the effect of salt on the aggregation number of SDS and using the distance of the dissociating group as a parameter. The conformations of the probes were analyzed theoretically using two dielectric constants, e.g., 2 and 78. Both the P-B analysis and conformation calculations can be interpreted by assuming that the acid groups dissociate very close to, or at, the interface. Our results are consistent with the assumption that the intrinsic pK(a)'s of both carboxylic and phenol groups of the salicylic acid probes used here can be taken as those in water. Using this assumption the micellar and salt effects on the pK(ap)'s of the (trialkylammonium)benzoate probes were described accurately using a cell model P-B analysis.     

Reactions of Amidosulfuric Acid Salts with Formaldehyde

Potassium amidosulfate reacts with formaldehyde at pH 7-12 to afford a mixture of dipotassium 4-hydroxy-1,3-diazabutane-1,3-disulfonate hydrate and tripotassium 6-hydroxy-1,3,5-triazahexane-1,3,5-trisulfonate HO(CH₂NSO₃K) _n ·H₂O (n = 2, 3). The reaction of the same compounds at pH 1-3 gives diammonium 1,3,5,7-tetraazabicyclo[3.3.1]nonane-3,7-disulfonic acid sulfate dihydrate.     

A mass spectrometric analysis of 4-hydroxy-2-(E)-nonenal modification of cytochrome c

Cytochrome c is a key mitochondrial respiratory protein that is particularly susceptible to modification during oxidative stress. The nature of this susceptibility is linked to the mitochondrial membrane being rich in esterified linoleic acid, which predisposes this organelle to the formation of lipid peroxidation products such as 4-hydroxy-2-(E)-nonenal (4-HNE). To better understand the nature of cytochrome c modification by 4-HNE, we initiated an in vitro study utilizing a combination of MALDI-TOF mass spectrometry, LC-ESI-MS/MS and isotope labeling to monitor 4-HNE modification of cytochrome c under various conditions. The overwhelming reaction observed is Michael addition by Lys side-chains in addition to the modification of His 33. While the Lys-4-HNE adducts were generally observed to be reversible, the 4-HNE-His 33 was observed to be stable with half of the formed adduct surviving the denaturation and proteolysis protocols used to generate proteolytic peptides for LC-ESI-MS/MS.     

Synthesis of 2-amino-4-hydroxy-1,3,5-triazanaphthalenes

The synthesis of 2-amino-4-hydroxy-6-amyl-1,3,5-triazanaphthalene (8) is described as a model sequence pertinent to preparation of 8-deazafolic acid and its analogs. Condensation of 2-acet-amido-4-hydroxy-6-pyrimidinealdehyde (3) with dimethyl 2-oxoheptylphosphonate afforded 1-(2′-acetamido-4′-hydroxy-6′-pyrimidinyl)-1-octene-3-one (4) as a key intermediate. Conversion of 4 to 1-(2′-amino-4′-hydroxy-5′ -phenylazo-6′ pyrimidinyl)-3-octanone (7) followed by reductive cyclization yielded 8 or its tetrahydro derivative (9) .     

二-(2-羟基-5-长链烷基苯基)-甲烷的合成

以脂肪酸、苯酚为原料, 经酰化反应、酯化反应、Fries重排、黄鸣龙还原等步骤, 得到正构长链烷基酚, 再与多聚甲醛在酸性催化剂下进行缩合反应, 生成二-(2-羟基-5-长链烷基苯基)-甲烷, 用核磁共振氢谱和碳谱、红外光谱和元素分析对产物进行了结构鉴定. 据上述反应路线, 以工业品壬基酚和多聚甲醛为原料, 合成出了二-(2-羟基-5-壬基苯基)-甲烷, 并对其工艺条件进行了研究. 结果表明, 选用草酸作催化剂, 烷基酚和甲醛物质的量比为2∶1, 130 ℃反应4 h, 产物产率达到60%, 且反应转化率和选择性分别为63%和95%.     

Organic peroxides—XIX: Decomposition of trialkylperoxy triazines

The kinetics of the decomposition of tri-t-butylperoxy-1,3,5-triazine (from trichloro-1,3,5-triazine and barium t-butyl peroxide in situ) follows the 1-order with an activation energy of 24.6 $\text{kcal}\text{mole}$. Isolated products are cyanuric acid and acetone. The reaction of trichloro-triazine with potassium cumyl peroxide yields cyanuric acid, isopropenyl phenyl ether, dicumyl peroxide, acetone and phenol, with barium 2-benzyl-2-propyl peroxide cyanuric acid, benzaldehyde and 2-benzyloxy-2-[2-benzyl-2-propylperoxy]-propane. The mechanism of the decomposition is discussed.     

4-Hydroxy-2-quinolones. 112. Reaction of 2-ethoxycarbonylmethyl-4H-3,1-benzoxazin-4-one with active methylene compounds

The reaction of 2-ethoxycarbonylmethyl-4H-3,1-benzoxazin-4-one with malononitrile in dry pyridine leads to 1-hydroxy-3,6-dioxo-4,6-dihydro-3H-pyrimido[1,2-a]quinoline-5-carbonitrile. Acetoacetic and cyanoacetic esters under analogous conditions form anilides of 4-hydroxy-2-oxo-1,2-dihydroquinoline-3-carboxylic acid while diethyl malonate gives N,N′-di-2-carboxyanilides of malonic acid. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 75–79, January, 2007.     

Oxidative Aromatization of 1,3,5‐Trisubstituted 4,5‐Dihydro‐1H‐Pyrazoles Efficiently by Tetrabromine‐1,3,5,7‐Tetrazatricyclo[3.3.1.13,7]Decane Complex,Br4‐Tatcd,as a Novel Reagent both Under Microwave Irradiation and at Room Temperature

Oxidation of 1,3,5‐trisubstituted 4,5‐dihydro‐1H‐pyrazoles to the corresponding pyrazoles has been achieved by utilizing tetrabromine‐1,3,5,7‐tetrazatricyclo[3.3.1.1^3,7]decane complex, Br₄‐TATCD, in glacial acetic acid under microwave irradiation and conventional thermal condition at room temperature with excellent yields.     

A Validated HPLC Method for Simultaneous Determination of 2-Hydroxy-4-methoxybenzaldehyde and 2-Hydroxy-4-methoxybenzoic Acid in Root Organs of Hemidesmus indicus

A reverse phase HPLC method was developed and validated for the simultaneous determination of 2-hydroxy-4-methoxybenzaldehyde and 2-hydroxy-4-methoxybenzoic acid in the root extracts of Hemidesmus indicus. A comprehensive validation of the method including sensitivity, linearity, reproducibility, accuracy, limit of detection (LOD) and limit of quantification (LOQ) was conducted using the optimized chromatographic conditions. The method was found to be linear (r > 0.998) in the range of 5–350 μg mL⁻¹ for 2-hydroxy-4-methoxybenzaldehyde and for 2-hydroxy-4-methoxybenzoic acid (r > 0.999) in the range 10–300 μg mL⁻¹. The method was found to be precise with inter-day precision values (% RSD) in the ranges of 0.61–1.76% for 2-hydroxy-4-methoxybenzaldehyde and 1.3–2.8% for 2-hydroxy-4-ethoxybenzoic acid while intra-day precisions (% RSD) of two analytes were in the range of 0.41–1.07 and 0.95–2.5%. The limits of detection (LODs) for 2-hydroxy-4-methoxybenzaldehyde and 2-hydroxy-4-methoxybenzoic acid were 0.84 and 2.34 μg mL⁻¹. The described method was fast, sensitive and reproducible, and thus well suited for routine analysis of these two compounds from root extracts of H. indicus and other plants.     

Efficient DMTMM Promoted Nucleoside Loading of CPG Solid Support for Oligonucleotide Synthesis

Abstract

A simple and efficient process for the attachment of protected 2′‐deoxynucleosides to the solid support controlled pore glass (CPG) via succinyl linkage using the mild, non‐carbodiimide dehydrating agent 4‐(4,6‐dimethoxy‐1,3,5‐triazin‐2‐yl)‐4‐methylmorpholinium chloride (DMTMM) has been developed. The protocol is cost effective, does not require anhydrous conditions and is easy to implement.     

1H NMR for quantifying sulfide trapping efficiency by using 1,3,5‐tris(2‐hydroxyethyl)‐1,3,5‐triazinane

Hydrogen sulfide (H₂S) is an extremely toxic colourless gas; it is corrosive and denser than air. It usually happens in oil and natural gas fields, refineries, coal mines, and in some industrial effluent treatment systems. This work presents an alternative method of monitoring and quantifying H₂S trapping efficiency by using 1,3,5‐tris(2‐hydroxyethyl)‐1,3,5‐triazinane as a sequestering agent, and sodium sulfide as a source of sulfide ion, through ¹H NMR spectroscopy. The results proved that the reaction occurs very quickly at 20 °C at pH 7 and 10. 3,5‐di(2‐hydroxyethyl)‐1,3,5‐thiodiazinane and 5‐(2‐hydroxyethyl)‐1,3,5‐dithiozinane were observed and quantified; it was evidenced that ¹H NMR spectroscopy can be applied as a fast and effective method to quantify H₂S trapping efficiency. Copyright © 2014 John Wiley & Sons, Ltd.     

Synthesis of a novel tripodand having 3-hydroxy-2-naphthoeic amide groups and its anion recognition ability

A novel tripodand having 3-hydroxy-2-naphthoeic amide groups was prepared by the reaction of 1,3,5-tris(aminomethyl)-2,4,6-trimethylbenzene with 3-allyloxy-2-naphthoeic acid chloride followed by thermal Claisen rearrangement. This tripodand can exhibit the anion binding ability in chloroform solution. In particular, it can bind with acetate, dihydrogen phosphate, and fluoride ions to form 1:1 complexes.     

Synthesis of 2-hydroxy-3-methylbut-3-enyl substituted coumarins and xanthones as natural products. Application of the Schenck ene reaction of singlet oxygen with ortho-prenylphenol precursors

Application of our original photooxidation-reduction methodology to prenylated dihydroxycoumarin and trihydroxyxanthone compounds led to the corresponding ortho-(2-hydroxy-3-methylbut-3-enyl)phenol derivatives with yields ranging from 8 to 65%. In most of the reported experiments, the oxidation products distribution, after the photooxygenation step, was controlled by the competition between the large group effect and the stabilising phenolic assistance effect. We also showed that ortho-(3-hydroxy-3-methylbut-1-enyl)phenol derivatives could be considered as biogenetic precursors of 2,2-dimethylbenzopyranic structures.     

Mild and Efficient Synthesis of Carboxylic Acid Anhydrides from Carboxylic Acids and Triazine Coupling Reagents

Abstract

Anhydrides of carboxylic acids were obtained in 53%–95% yield by treatment of appropriate carboxylic acids with 2‐chloro‐4,6‐dimethoxy‐1,3,5‐triazine (CDMT) or 2,4‐dichloro‐6‐methoxy‐1,3,5‐triazine (DCMT) in the presence of N‐methylmorpholine. It has been proved that synthesis proceeds via triazine active esters 3a,b, which are able to acylate carboxylate anion but not less nucleophilic carboxylic acid.     

Chemical Graft of Cellulose with the Ion-Pair Emulsion Containing the Reactive Groups and Its Dyeing Properties

Chemical graft of cellulose with ion-pair disperse emulsion containing the reactive groups was investigated. The ion-pair disperse systems were consisted of a 1,3,5-triazine derivative containing the reactive groups, 2,4,6-tri[(2-hydroxy-3-trimethyl-ammonium)propyl]-1,3,5-triazine chloride (Tri-HTAC) and 2,4,-bichloro[(6-sulfanilic acid)-1,3,5-triazine (Bi-CSAT). Compared with unmodified cellulose, the modified cotton exhibited different behavior towards dyeing. The modified cotton could be dyed with reactive dyes without the addition of salt. The color yield was higher than that on untreated cotton, despite of the addition of large amounts of salt in the latter case. Cotton fabric modified with ion-pair disperse emulsion was imparted good level dyeing properties. The dyeing rate was slower in the presence of the ion-pair compounds than that in the present of the only cationic compounds.     

Aerobic oxidation of 1,3,5-triisopropylbenzene using N-hydroxyphthalimide (NHPI) as key catalyst

The first systematic study on the aerobic oxidation of 1,3,5-triisopropylbenzene was examined by the use of N-hydroxyphthalimide (NHPI) as a key catalyst. It was found that 1,3,5-triisopropylbenzene was efficiently oxidized with O₂ in the presence of a catalytic amount of NHPI and azobisisobutyronitrile (AIBN) at 75 °C. Upon treatment of the resulting products with sulfuric acid followed by acetic anhydride led to 5-acetoxy-1,3-diisopropylbenzene and 3,5-diacetoxy-1-isopropylbenzene as major products and a small amount of 1,3,5-triacetoxybenzene. When t-butylperoxypivalate (BPP) was employed as a radical initiator, the oxidation could be achieved in good yield even at 50 °C. This oxidation provides a facile method for preparing phenol derivatives bearing an isopropyl moiety, which can be used as pharmaceutical starting materials.     

Novel One-Pot Multicomponent Synthesis of Substituted 2,3-Dihydro-2-(6-(4-hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)-7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazin-3-yl)phthalazine-1,4-diones and Substituted 3-[3-(N′-Benzylidene-hydrazino)-7H-[1,2,4] triazolo[3,4-b][1,3,4]thiadiazin-6-yl]-4-hydroxy-6-methyl-pyran-2-ones

A one-pot procedure has been developed for the synthesis of substituted 2,3-dihydro-2-(6-(4-hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)-7H-[1,2,4]triazolo[3,4-b] [1,3,4]thiadiazin-3-yl)phthalazine-1,4-diones by reaction of 3-(2-bromoacetyl)-4-hydroxy-6-methyl-2H-pyran-2-one, 4-amino-5-hydrazino-4H-[1,2,4]triazole-3-thiol, and phthalic anhydrides in acetic acid medium. Similarly, a one-pot, three-component synthetic procedure has been developed for substituted 3-[3-(N¹-benzylidene-hydrazino)-7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazin-6-yl]-4-hydroxy-6-methyl-pyran-2-ones from 3-(2-bromoacetyl)-4-hydroxy-6-methyl-2H-pyran-2-one, 4-amino-5-hydrazino-4H-[1,2,4]triazole-3-thiol, and various aromatic aldehydes in absolute ethanol and a few drops of glacial acetic acid.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]     

The synthesis of hexahydro-6H-dibenzo[b,d]pyrans: Derivatives of 9-Nor-9β-hydroxyhexahydrocannabinol

To assess the importance of the phenol functionality in cannabinoids for analgetic activity a new series of 9-nor-9β-hydroxyhexahydrocannabinoids was prepared. The synthesis of 1-substituted (H, CH₂OH, OH, NH₂) 6aβ,7,8,9,10,10aα-hexahydro-9β-hydroxy-6,6-dimethyl-3-[1-methyl-4-phenylbutoxy]-6H-dibenzo[b,d]pyrans from 3,5-dihydroxystilbene, 3,3′,5,5′-tetrahydroxystilbene or 1,3,5-trihydroxybenzene is described. Relative stereochemistry and structure confirmations were obtained by nmr and X-ray crystal analysis.