Solid-liquid Phase-transfer Catalysis Conditions Research Articles

A Study on the Rearrangement of Dialkyl 1-Aryl-1-hydroxymethylphosphonates to Benzyl Phosphates

The phospha-Brook rearrangement of dialkyl 1-aryl-1-hydroxymethylphosphonates (HPs) to the corresponding benzyl phosphates (BPs) has been elaborated under solid-liquid phase transfer catalytic conditions. The best procedure involved the use of triethylbenzylammonium chloride as the catalyst and Cs2CO3 as the base in acetonitrile as the solvent at room temperature. The substrate dependence of the rearrangement has been studied, and the mechanism of the transformation under discussion was explored by quantum chemical calculations. The key intermediate is an oxaphosphirane. The one-pot version starting with the Pudovik reaction has also been developed. The conditions of this tandem transformation were the same, as those for the one-step HP→BP conversion.

Regioselective O-Sulfonylation of N,N-Bis(2-hydroxyalkyl)tosylamides as a Synthetic Key Step to Enantiopure Morpholines.

The synthesis of enantiopure 2,6-disubstituted morpholines was realized through sequential ring opening of two different optically pure oxiranes by a tosylamide, under solid-liquid phase-transfer catalysis (SL-PTC) conditions, mono-O-sulfonylation of the resulting tosylamido-2,2'-diol, and cyclization to the morpholine. The crucial step, the regioselective formation of the monosulfonate, was controlled by taking advantage of the different stereo, electronic, and coordination properties of the oxirane-derived side chains in the diol backbone. As an application of this protocol, a new morpholine-3-carboxamide was synthesized starting from threonine.

The novel synthetic route of 3,5-dimethyl-1-(3-phenylpropyl)-1H-pyrazole under solid–liquid phase transfer catalysis conditions assisted by an ultrasound application—A study of some kinetic parameters

The kinetic study for synthesis of 3,5-dimethyl-1-(3-phenylpropyl)-1H-pyrazole was studied successfully by reacting the 3,5-dimethyl pyrazole with 1-bromo-3-phenyl propane under phase transfer catalysis and ultrasonic irradiation conditions using aqueous solution of NaOH (5 g or 0.25 g/ml), excess amount of bromobenzene and tetrahexyl ammonium bromide as a phase transfer catalyst. The reaction was carried out at 40 °C under pseudo-first order conditions and was monitored by gas chromatography (GC). Kinetic reaction found to follow ‘pseudo first order’ rate law. From the experimental data, a rate expression had been developed to explain the kinetic behavior of the reaction from which the apparent rate constant (kapp) of the organic phase was attained. The effects of agitation speed, amount of sodium hydroxide, effect of quaternary ammonium salts, amount of catalyst and temperature on the reaction were also studied.

ChemInform Abstract: A New Approach to 4,6‐Disubstituted‐3,4‐dihydropyran‐2‐ones by Domino Michael Addition‐Cyclization Reaction under PTC Conditions.

AbstractThe new domino process allows the preparation of dithioacetals (III).

A new approach to 4,6-disubstituted-3,4-dihydropyran-2-ones by Domino Michael addition-cyclization reaction under PTC conditions

Domino Michael addition-cyclization reactions of α,β-unsaturated carbonyl compounds with activated 1,3-dithiane-2-carbothioate esters under solid-liquid phase transfer catalysis conditions provide 4,6-disubstituted-3,4-dihydropyran-2-one-3,3-dithioacetals in good chemical yield. Desulfurization proceeds chemoselectively under mild conditions affording 3,4-dihydropyran-2-ones in high yields.

Synthesis of 3,5-dimethyl-1-prop-2-enylpyrazole under solid–liquid phase transfer catalytic conditions assisted by ultrasonic irradiation—A kinetic study

The synthesis of 3,5-dimethyl-1-prop-2-enylpyrazole was successfully carried out by reacting the 3,5-di-methyl pyrazole with 3-bromoprop-1-ene in small amount of KOH and organic solvent solid–liquid phase medium under phase transfer catalysis (PTC) and almost anhydrous conditions assisted by the ultrasonic irradiation in the 5h at 50°C. The main target of this carried work was to provide evidence that the reaction conditions by investigation of the kinetic behaviour, activation energy, reaction mechanism and the related parameters in the solid–liquid PTC reaction besides on to reduce time and temperature of reaction. A rational mechanism for the reaction has been derived base on the experimental result. This kinetic reaction follows pseudo first order rate law. A rate expression had developed to explain the kinetic behaviours from which the apparent rate constant (kapp) of the organic-phase reaction was obtained via investigated data. Kinetics of the reaction, including the effects of agitation speed, quantity of potassium hydroxide, quantity of water, temperature, quantity of tetraoctylammonium bromide (TOAB), volume of cyclohexanone, quarternary ammonium salts and organic solvents on the conversion of RBr and the apparent rate constant (kapp) were investigated in full length. Rational explanations for the resulting phenomena are also provided.

Design, synthesis and antiproliferative properties of some new 5-substituted-2-iminobenzimidazole derivatives

Some new 1,3,5-substituted-2,3-dihydro-2-imino-benzimidazoles were synthesized under solid–liquid phase transfer catalysis conditions using 5-substituted-2-aminobenzimidazoles as precursors in order to assess their cytotoxicity respectively proliferative activity. The structures of the compounds were confirmed by IR, 1H NMR, 13C NMR and elemental analysis.Compounds 9–10, 12 and 16–17 were evaluated for their cytotoxical effect on four cancer cell lines: HT-29, breast cancer cells MDA-MB-231, HeLa, HepG2 and as well as human diploid cell line Lep-3.Significant cytotoxicity of hydrazone 16 against MDA-MB-231 was established by biologically study, the IC50 was 6.2 nM while the EC50 value to Lep 3 is 0.21 nM. Relative high antiproliferative effects of the acetate 12 and compound 16 against HT-29 were ascertained and the calculated IC50 values were IC50 – 0.85 nM and IC50 – 2.83 nM respectively. Cytotoxic activity against HeLa and HepG2 cells was demonstrated by hydrazone 17, IC50 was 7.2 nM and 117 nM respectively. All tested compounds revealed proliferative activities to human diploid cell line Lep-3. The EC50 values were in the range from 0.05 to 16.91 nM. The obtained results prove the selective cytotoxicity of the tested compounds and are promising for further evaluation of the investigated compounds in vivo experiments using experimentally induced tumors in laboratory animals.

A Safe Two-Step Process for Manufacturing Glycidyl Nitrate from Glycidol Involving Solid–Liquid Phase-Transfer Catalysis

A new and safer two-step process for manufacturing glycidyl nitrate from glycidol is reported. In the first step glycidyl tosylate is obtained by reacting glycidol with p-tosyl chloride in the presence of triethylamine according to any one of the well-known procedures for obtaining tosyl esters described in the literature. In the second step, glycidyl tosylate is reacted with NaNO3 in refluxing acetonitrile under solid–liquid phase-transfer catalysis conditions using tetrabutylammonium nitrate as catalyst. Acetonitrile and the phase-transfer catalyst were recycled 12 times without deactivation, yielding 99% pure glycidyl nitrate in a cumulative isolated yield of 81.5% with a catalyst turnover number of 85.7 mol substrate per mol phase-transfer catalyst. This procedure avoids the use of the dangerous reactants used in the current manufacturing processes of glycidyl nitrate and could be useful as a safe and general method for obtaining nitrate esters.

ChemInform Abstract: Synthesis of 2-Amino Acids via Selective Mono-N-alkylation of Trichloroacetamide by 2-Bromo Carboxylic Esters Under Solid-Liquid Phase-Transfer Catalysis Conditions.

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ChemInform Abstract: Novel Concise Synthesis of 2-Substituted 3,4-Dihydro-2H-1,4-benzoxazines by Ring Opening of Glycidols under Solid-Liquid Phase Transfer Catalysis Conditions.

The ring opening of glycidols with N-(2-fluorophenyl)toluene-p-sulfonamide under SL-PTC conditions, followed by ring closure with ButOK, provides a novel high yielding synthesis of 2-substituted 3,4-dihydro-2H-1,4-benzoxazines.

ChemInform Abstract: Phase Transfer Catalysis: Some Recent Applications in Organic Synthesis

Abstract A survey dealing with the use of anhydrous potassium carbonate as an efficient base for promoting organic reactions under solid–liquid phase transfer catalysis (SL-PTC) conditions is reported. In particular, the generation in situ of trifluoro- and trichloroacetamidide, and reactions of these azaanions with 2-bromocarboxylic esters and epoxides, affording protected α-amino acids and β-amido alcohols, respectively, are described. The reduction of allylic nitroderivatives with CS 2 to oximes or nitriles under SL- and liquid–liquid PTC (LL-PTC) is also presented. Finally, new preparation methods and a study of the reactivity of quaternary onium fluorides, hydrogendifluorides and dihydrogentrifluorides, together with the use of dihydrogentrifluorides as hydrofluorinating agents under SL-PTC conditions, are reported.

ChemInform Abstract: Synthesis of Indan-Based Unusual α-Amino Acid Derivatives under Phase-Transfer Catalysis Conditions.

Conformationally constrained cyclic α-amino acid derivatives were synthesized under solid-liquid phase-transfer catalysis conditions. This methodology involves the bis-alkylation of ethyl isocyanoacetate with various α,α‘-dibromo-o-xylene derivatives [α,α‘-dibromo-o-xylene 5, 2,3-bis(bromomethyl)-1,4-dimethoxybenzene 6, 1,2-bis(bromomethyl)-4,5-dibromobenzene 7, 2,3-bis(bromomethyl)naphthalene 8, 1,8-bis(bromomethyl)-naphthalene 9, 6,7-bis(bromomethyl)-2,2-dimethyl-1H-phenalene-1,3(2H)-dione 10, 2,3-bis(bromomethyl)-1,4-anthraquinone 11, 6,7-bis(bromomethyl)quinoxaline 12, 3,4-bis(bromomethyl)furan 13, 1,2,4,5-tetrakis(bromomethyl)benzene 28, and hexakis(bromomethyl)benzene 30] using potassium carbonate as a base and tetrabutylammonium hydrogensulfate as a phase-transfer catalyst to give corresponding isonitrile derivatives, which upon hydrolysis with HCl in ethanol gave amino esters. Using this method electron-deficient as well as electron-rich and halogen-substituted indan-based α-amino acids were prepa...

Simultaneous C- and N-Alkylation of 2-Oxo-4,6-diaryl-1,2,3,4-tetrahydropyridine-3-carbonitrile Under Solid–Liquid Phase-Transfer Conditions

The alkylation of 2-oxo-4,6-diaryl-1,2,3,4-tetrahydropyridine-3-carbonitrile 1 has been carried out using different alkyl/arylating agents in solid–liquid phase-transfer catalysis conditions. The aim was to study the effect of steric hindrance offered by the aryl group in the sixth position of the pyridine ring on the ambient N- vs. O-alkylation ratio. Simultaneous C- and N-alkylation was encountered and confirmed by x-ray crystallography. Our study to gain exclusive regiocontrol for simultaneous alkylation was carried out. An alternative route for C‒C bond formation was also established by the removal of the cyano functionality.

Efficient Approach to the Synthesis of Ethyl 3-Amino-4,6-diarylfuro[2,3-b]pyridine-2-carboxylate

Novel ethyl 3-amino-4,6-diarylfuro[2,3-b]pyridine-2-carboxylate were synthesized by Thorpe–Ziegler cyclization using solid–liquid phase-transfer catalysis conditions.

A Straightforward Synthesis of Enantiopure 2,6-Disubstituted Morpholines by a Regioselective O-Protection/Activation Protocol

Enantiopure 2,6-disubstituted morpholines have been synthesized through the ring opening of chiral, nonracemic oxiranes with nitrogen nucleophiles, under solid-liquid phase-transfer catalysis (SL-PTC) conditions. The β-hydroxytosyl amides resulting from the ring opening of a first epoxide with TsNH2 was used as nucleophile, after protection of the hydroxyl group, in the reaction with a second oxirane. The morpholine skeleton has been generated through standard functional group chemistry, followed by cyclization of the intermediate β-hydroxy-β′-tosyloxy-tosylamides carried out under SL-PTC conditions. N-Tosyl morpholines produced can be employed as building blocks in the synthesis of pharmaceuticals and as chiral tools.

A practical approach to the synthesis of enantiomerically pure 2,6-disubstituted morpholines under phase transfer catalysis conditions

A novel, straightforward and high yielding synthesis of enantiomerically pure 2,6-disubstituted morpholines has been developed through the regioselective cyclization of diols. Cyclization precursors have been obtained by the ring opening of commercially available chiral epoxides under solid–liquid phase transfer catalysis conditions (SL-PTC).

Synthesis of 2-substituted 3,4-dihydro- 2H-1,4-benzoxazines through ligandless copper-catalyzed cyclization of hydroxysulfonamides under phase-transfer catalysis conditions

The ring closing under solid–liquid phase-transfer catalysis conditions (SL-PTC) of hydroxysulfonamides 7, bearing a leaving group in the ortho position of the aryl moiety, generates 2-substituted-3,4-dihydro- 2H-1,4-benzoxazines 4 in good to excellent yields. In the case of hydroxysulfonamides 7 bearing a bromine or iodine atom as a leaving group, a copper(I) salt is used to enable the reaction to occur.

Synthesis, structure and application of a new class of Tr-podands derived in phase-transfer catalysis

Triton X surfactants are used in numerous commercial and industrial products. Large amounts of such surfactants and their various residual biodegradation by-products are ultimately released into the environment. The first synthesis of the group of Tr-polypodands (Triton polypodands), with different central atoms, such as Si, B or P, is reported. Results of this study demonstrate the potential of these compounds in some organic reactions in phase-transfer catalysis (PTC) conditions. The catalytic activity of Triton X ( 1) and Tr-podands ( 2– 8) has been evaluated in an ion promoted reaction under solid–liquid phase-transfer catalysis conditions and compared with that of the earlier studied Si-podands ( 9– 11), used as PTC agents.

Efficient and Convenient Synthesis of Diethers from Furoin Under Ultrasound and Solid-liquid Phase Transfer Catalysis Conditions

Efficient and Convenient Synthesis of Diethers from Furoin Under Ultrasound and Solid-liquid Phase Transfer Catalysis Conditions

An efficient and convenient procedure for the synthesis of 2-alkyl-2-alkoxy-1,2-di(furan-2-yl)ethanone under ultrasound in the presence of solid–liquid phase transfer catalysis conditions

Irradiation with ultrasound is found to facilitate the synthesis of 2-alkyl-2-alkoxy-1,2-di(furan-2-yl)ethanone in the presence of tetrabutylammonium bromide (TBAB) as solid–liquid phase transfer catalysis. A higher yields (>70%) and shorter reaction time (<15min) give this method obvious advantages over the conventional ones.