Solid-liquid Phase-transfer Catalysis Conditions Research Articles

Substituted pyridopyrimidinones, 1: Convenient PTC alkylation and halogenation of 2‐hydroxy‐4H‐pyrido[1,2‐a]pyrimidin‐4‐one

AbstractAlkylation of 2‐hydroxy‐4H‐pyrido[1,2‐a]pyrimidin‐4‐one (1) was investigated under solid–liquid phase transfer catalysis conditions (PTC), using tetrabutylammonium bromide and potassium carbonate. The reaction with alkyl halides led to the formation of various 2‐alkoxy products, in fair yields. Reaction of compound 1 with epichlorohydrin and chloroacetonitrile, under the same PTC conditions, afforded novel O1,O3‐disubstituted glycerol and oxazolopyridopyrimidone betaine derivatives, respectively. Some 3‐halo‐, 3,3‐dihalo, and/or 2,3‐dihalopyrido[1,2‐a]pyrimidines were also prepared using different halogenating agents at different reaction conditions. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:19–27, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20245

S,S-Dimethyl Dithiocarbonate as a Valuable Starting Material for the Synthesis of 5-Substituted Oxazolidinones Under Solid-Liquid Phase Transfer Catalysis (SL-PTC) Conditions

N-Alkyl and N-aryl 5-substituted oxazolidinones 12-19 were prepared in good to excellent yields by reaction of N-alkyl and N-aryl 1,2-amino alcohols 3-10 with S,S-dimethyldithiocarbonate (11) in the presence of solid NaOH under SL-PTC conditions. The procedure is particularly suitable for scale-up the process involving the use of cheap and ecosafe reagents under mild reaction conditions. Keywords: S,S-dimethyldithiocarbonate, 1,2-amino alcohols, 5-substituted oxazolidinones, phase-transfer catalysis, carbonylation reaction

Synthesis of N-substituted imides via solid-liquid phase-transfer catalytic reaction

N-substituted imides (RSIs) were synthesized from the reactions of alkylbromides (RX) and potassium salts of imides (KSIs) under solid-liquid phase-transfer catalytic conditions (SL-PTC). No water is required in the reaction system. In this work, serious hydration of KSIs is avoided using SL-PTC to synthesize RSIs. The reaction catalyzed by quaternary ammonium salts is greatly enhanced in the solid-liquid solution

Chemoselective N-Alkylation of Di-N,O-protected Tyrosine through Specific Oxy-Anion Solvation by Non-Hydrogen Bonding Donor Solvents

N-(2-Nitro-benzenesulfonyl) activated l-tyrosine methyl ester has been directly N-alkylated under solid-liquid phase-transfer catalysis (SL-PTC) conditions and in a coordinating non-hydrogen bonding donor (non-HBD) solvent, which reduces through specific solvation the nucleophilicity of the oxy-anionic center of the N,O-dianion formed by action of an anhydrous inorganic carbonate.

Kinetic study of synthesizing N-butylphthalimide under solid–liquid phase-transfer catalysis conditions

The synthesis of N-butylphthalimide (PTR) from the reaction of 1-bromobutane and potassium salt of phthalimide (PTK) was carried out successfully in a solid–liquid phase-transfer catalytic condition (SL-PTC) instead of reaction in a liquid–liquid two-phase medium. No water is required in the reaction system. The advantage of using SL-PTC to synthesize organic chemicals is to avoid a serious hydration of potassium salt of phthalimide from the reaction of 1-bromobutane and potassium salt of phthalimide in a liquid–liquid two-phase solution. The reaction is greatly enhanced in the solid–liquid solution catalyzed by quaternary ammonium salts. The reaction mechanism is proposed and verified by examining the experimental evidence. A kinetic model is proposed in which a pseudo first-order rate law is sufficient to describe the results. Kinetics of the reaction, including the effects of agitation speed, amount of acetonitrile, organic solvents, amount of tetrabutylammonium bromide, quaternary ammonium salts, amount of water and temperature on the conversion of 1-bromobutane and the apparent rate constant ( k app) were investigated in detail. Rational explanations to account for the phenomena on the results were made.

Selective syntheses of novel polyether fullerene multiple adducts.

We have applied a modified macrocyclic tether approach to control multiple additions to C60. The technique of 3He NMR was used to confirm the selective formation of specific C60 multiple adducts by the macrocyclic tether approach. An oligoglycol was used as a flexible linker to produce macrocyclic polyether-linked malonates 5, 6, 8, and 9 under solid-liquid PTC (phase-transfer-catalysis) conditions. The formation of a single C60 tris-adduct, 3, from macrocyclic malonate 1 and 3He@C60 was proven by 3He NMR. Similarly, multiple additions to C60 of macrocyclic polyether malonate 5 gave C60 bis-adduct 10 selectively, while the reaction of C60 with macrocyclic malonate 8 gave bis-adducts 11 and 12. A similar process with macrocyclic malonate 6 gave tris-adduct 13 with high selectivity as well. Saponification of these C60 multiple adducts gives the corresponding polyacids that are potentially useful in biological applications. Macrocyclic polyether fullerenes are a new class of ionophores, which could be interesting for molecular recognition and for the development of biosensors.

The building block approach to unusual alpha-amino acid derivatives and peptides.

The building block approach was identified as a useful alternative to the commonly used Bücherer-Berg method for the preparation of cyclic unusual alpha-amino acid derivatives. The symmetrical building blocks were prepared by dialkylation of ethyl isocyanoacetate under solid-liquid phase transfer catalysis conditions while the unsymmetrical building blocks were prepared by a stepwise alkylation of the O'Donnell Schiff base. Metathesis reactions, Suzuki couplings, and cycloaddition reactions were utilized to assemble the building blocks.

Synthesis of Vinyl Monomers With Active Azaaromatic Groups. Phase-transfer Catalytic Approach

An efficient method based on the alkylation-elimination reactions under solid-liquid phase transfer-catalysis conditions (S/L PTC) is reported for the preparation of N-vinyl derivatives of azaheterocyclic compounds.

A Convenient Preparation of Unsymmetrical Ketones from Borinates using Phase Transfer Catalysis

Unsymmetrical ketones were prepared from borinates via the insertion of dichlorocarbene into the C–B bond under solid–liquid phase transfer catalysis conditions and oxidation with alkaline hydrogen peroxide in 50–78% yields.

N-Monoalkylation of α-Amino Acid Esters under Solid-Liquid PTC Conditions

N-(2-Nitrophenylsulfonyl)- (o-NBS-AA-OMe, 4) and N-(4-Nitrophenylsulfonyl)-α-amino acid methyl esters (p-NBS-AA-OMe, 5) were N-alkylated with a variety of alkyl halides 6 under solid-liquid phase-transfer catalysis (SL-PTC) conditions, affording the alkylated products o-NBS-N-R2-AA-OMe 7 and p-NBS-N-R2-AA-OMe 8 in excellent yields without any detectable racemization.

Synthesis of indan-based unusual alpha-amino acid derivatives under phase-transfer catalysis conditions.

Conformationally constrained cyclic alpha-amino acid derivatives were synthesized under solid-liquid phase-transfer catalysis conditions. This methodology involves the bis-alkylation of ethyl isocyanoacetate with various alpha,alpha'-dibromo-o-xylene derivatives [alpha,alpha'-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 alpha-amino acids were prepared. The preparation of bis-indan as well as tris-indan alpha-amino esters is also described.

Phase transfer catalysis: some recent applications in organic synthesis

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.

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: Highly Diastereoselective Monoalkylation and Michael Addition of N‐(Diphenylmethylene)glycinesultam under Solid—Liquid Phase—Transfer Catalysis Conditions Using Potassium Carbonate as Base.

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Highly diastereoselective monoalkylation and Michael addition of N-(diphenylmethylene)glycinesultam under solid–liquid phase-transfer catalysis conditions using potassium carbonate as base

Treatment of a sultam-derived N-(diphenylmethylene)glycinate equivalent 1 with activated (allylic and propargylic) organic bromides and with Michael acceptors under solid–liquid phase-transfer catalysis conditions, using potassium carbonate as base, affords the monoalkylated compounds with high diastereoselectivity (>97% d.e.).

Influence of ultrasound power on the alkylation of phenylacetonitrile under solid-liquid phase transfer catalysis conditions

The influence of ultrasound power on the C-alkylation of phenylacetonitrile by ethyl bromide was studied under solid-liquid phase transfer catalysis in the presence of potassium hydroxide and tetrabutylammonium hydrogenosulfate. Experimental results are reported on the influence of the ultrasonic power on the yields. The optimum efficiency of ultrasound is determined and the way in which ultrasound power may affect the yields is discussed.

Synthesis of conformationally constrained α-amino acid derivatives using ethyl isocyanoacetate as glycine equivalent

Some novel cyclic α-amino acid derivatives are prepared under solid-liquid phase-transfer catalytic conditions. Some of these amino acids prepared here are not directly accessible by the known methods.

Phase-Transfer-Catalyzed Synthesis Of N-Aryl-N′-(2-chlorobenzoyl)-thiourea Derivatives

Reaction of aromatic amines with 2-chlorobenzoyl chloride and ammonium thiocyanate under the condition of solid-liquid phase-transfer catalysis using polyethylene glycol-400(PEG-400) as the catalyst yielded N-aryl-N'-(2-chlorobenzoyl)thioureas 3a—3j in good to excellent yield.

Ethyl N-(diphenylmethylene)glycinate as anionic glycine equivalent. Monoalkylation, dialkylation and Michael additions under solid-liquid phase-transfer catalysis

Ethyl N-(diphenylmethylene)glycinate, 1, undergoes monoalkylations, dialkylations and Michael additions to ethylenic and acetylenic acceptors under appropriate solid-liquid phase transfer catalysis conditions. Further transformations of the α-disubstituted ketimines lead to α-alkylated aspartic and glutamic acid derivatives 10, 15, 19 and 26, to bicyclic amino acids or derivatives featuring pyrazolone and isoxazolone moieties 30 and 33, and to α-substituted ( E)-3,4-dehydroglutamic acids.

SYNTHESIS OF SOME CONDENSEDs-TRIAZOLE HETEROCYCLES USING PHASE-TRANSFER CATALYSIS TECHNIQUE

Abstract Some condensed heterocyclic systems were obtained by reacting 3-phenyl-4-amino-s-triazole-5-thiol 1 as a dianionic ambident compound containing N− and S− poles with some tetrahalo- and dihalo derivatives as well as α-haloketones and α-halonitrile derivatives under solid-liquid phase-transfer catalysis conditions.