Organic Reactions in Water: Synthesis of Phenacyl Esters from Phenacyl Bromide and Potassium Salts of Aromatic Acids in the Presence of β‐Cyclodextrin

Abstract

A convenient and facile synthesis of phenacyl esters is reported by the reaction of phenacyl bromide with potassium salts of aromatic acids in the presence of β‐cyclodextrin in water under neutral conditions.     

One-Pot Synthesis of Phenacyl Esters from Acetophenone, [Bmim]Br3, and Potassium Salts of Carboxylic Acids Under Solvent-Free Conditions

One-pot synthesis of phenacyl esters from acetophenone, [Bmim]Br₃, and potassium salts of carboxylic acids under solvent-free conditions gave the corresponding phenacyl esters with excellent yields.     

Stereochemical control in microbial reduction. Part 31: Reduction of alkyl 2-oxo-4-arylbutyrates by baker's yeast under selected reaction conditions

Treatment of baker's yeast with phenacyl chloride in an aqueous–organic solvent has been proven to be an effective method of inhibiting the enzymes that afford (S)-enantiomers of α-hydroxy esters in the reduction of α-keto esters. The procedure is effective for the whole-cell system to produce the (R)-product with high chemical yield and high enantiomeric excess.     

PHOTOLYSIS OF PHENACYL ESTERS IN A TWO-PHASE SYSTEM

ABSTRACT

Phenacyl esters are useful photoremovable protecting groups for carboxylic acids in organic synthesis and biochemistry. In this work, simple one-pot arrangements of the phenacyl and 2,5-dimethylphenacyl ester photolysis are proposed. The reactions were performed in both the benzene/water two-phase system and in water. Cetyltrimethylammonium bromide was found to increase substantially the efficiency of the deprotection as well as the purity of the products by lowering the interfacial tension between the phases. Utilizing water as a medium significantly reduced the necessity to use environmentally malign organic solvents. The overall yields varied from 72 to 98% depending on the reaction conditions.     

Liquid Chromatographic Determination of Valproic Acid in Human Serum

Abstract

The concentration of the antiepilepsy drug valproic acid (2-propylpentanoic acid) was determined in both a processed freeze dried human serum material and patient serum samples obtained from a clinical laboratory. The freeze dried material is being issued by the National Bureau of Standards as Standard Reference Material 1599. The analytical procedure developed involves organic extraction of valproic acid and an internal standard (cyclohexane-carboxylic acid) from the serum matrix; derivatization of the carboxylic acids to phenacyl esters; measurement of the analyte and internal standard species by reversed-phase high performance liquid chromatography. The results obtained on both types of samples compare favorably with results obtained using more conventional gas chromatographic approaches.     

Synthesis of Phenacyl Esters by Using PTC and Dibenzo-[18]-crown-6

In view of the importance of phenacyl esters as a protecting groups, a simple and efficient method is now reported here for synthesis of phenacyl esters in quantitative yield and high purity under mild reaction condition by using phase transfer catalyst and dibenzo-[18]-crown-6. It has been demonstrated that the spatial coordination of ion and ligand cavity plays important role in using crown ethers.     

Reactions of ortho oxy-substituted benzyl and phenacyl bromides in dimethyl sulphoxide

o-Acetoxy- and o-benzoyloxy-benzyl bromides and tosylates oxidatively rearrange in moist dimethyl sulphoxide to o-hydroxybenzyl esters; o-acetoxy- and o-benzoyloxy- phenacyl bromides rearrange to mixtures of 2-hydroxycoumaran-3-ones and o-hydroxyphenacyl esters; o-hydroxyphenacyl bromides also yield 2-hydroxycoumaran-3-ones, together with o-hydroxyphenacyl alcohols. 2-Acetoxybenzaldehyde is reductively rearranged by sodium borohydride to o-hydroxybenzyl acetate.     

Expedient Synthesis of 6-Aryl Derivatives of 3,4-Dihydro-1,4,4a,6a-tetraaza-benzo[a]fluoren-2-one: A New Heterocyclic Framework

3,4-Dihydro-1,4,4a,6a-tetraaza-benzo[a]fluoren-2-one, a new tetracyclic heterocyclic framework, is designed through a simple and convenient synthetic sequence. Its 6-aryl derivatives are synthesized starting from 1H-indole-2-carboxylic acid. The reaction of differently substituted phenacyl bromides with 1H-indole-2-carboxylic acid and POCl₃-mediated cyclization of the resultant 1H-indole-2-carboxylic acid phenacyl ester provided 2-oxa-4a-aza-fluoren-1-one, and its sequential reaction with hydrazine and 2-chloro-acetamide furnished the desired new heterocyclic compounds 7a–f.     

Polyketoetheresters from 4,4′-Dichloroacetyldiphenyl Ether and their Characterization

Benzyl chloride and phenacyl chloride are reported to condense with sodium acetate or sodium benzoate, affording the corresponding esters [1–4]. This suggested that a dichloride monomer can poly condense with a sodium dioate, affording a polyester. Akhmedzade and Yasnopolskii reported one such polyester synthesis based on polycondensation of p-xylylene dihalide with sodium terephthalate [5]. As phenacyl chloride is more reactive than benzyl chloride is more reactive than benzyl chloride [4], 4,4′-dichloroacetyldiphenyl ether (DADE) should prove even more reactive than a dichloride of the Ar(CH₂Cl)₂ type. The work presented here comprises a study of the polycondensation of DADE with sodium adipate (ADP), sebacate (SEB), or terephthalate (TER).     

A Convenient Synthesis of 2-Amino-1,3- selenazoles Using Ionic Liquid and Microwave Irradiation

Abstract

A simple and environmentally benign synthesis of 2-amino-1,3-selenazoles by microwave irradiation using 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF₄) ionic liquid (IL) is described. Acyl halides, phenacyl halides, and α-bromo-β-keto esters easily undergo condensation with selenourea in ([Bmim]BF₄) by microwave irradiation to afford the desired products of good purity in excellent yields. The ionic liquid can be easily recovered and reused at least 10 times without losing its activity. The duration of the reaction ranges from 4–6 min.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.

GRAPHICAL ABSTRACT      

An Improved Spectrophotometric Method for Determination of Penicillins Alone and in Pharmaceutical Dosage Forms

Abstract

A new spectrophotometric method for determining penicillins has been developed. A known volume of the penicillin solution is heated at 95[ddot]C for 70 min with ammonium molybdate, in sulphuric acid medium and the absorbance of the blue species formed is measured at 670 nm. The method has been successfully applied for the determination of thirteen commercially available penicillins. Beer's law is valid for up to 35-90 μg/ml of antibiotic (according to the penicillin). The procedure has been used for analysing some pharmaceutical preparations for these drugs, e.g., injections and capsules. The sensitivity of the method is largely increased with respect to the vanadate method previously described.     

SYNTHESIS OF N-PHOSPHOPEPTIDES COUPLED BY DICHLOROTRIPHENYLPHOSPHORANE

Coupling of N-phosphoamino acids 2 and amino acid methyl esters by dichlorotriphenylphosphorane 3 produced N-phosphopeptide methyl esters 5, which were sequentially hydrolyzed in triethylamine or dilute NaOH aqueous solution. The target products N-phosphodipeptides 6 were obtained in reasonable yields and high purity after isolation using extraction method. The convenient and efficient approach could be generally used for synthesis of polypeptides.     

A novel and efficient method for cleavage of phenacylesters by magnesium reduction with acetic acid

[reaction: see text] In the present study, we use magnesium turnings as a new deprotection reagent for the phenacyl group during orthogonal organic synthesis in the presence of other esters and sensitive protecting groups. By applying the new magnesium turnings/acetic acid deprotection method, phenacyl group can be more easily combined with other protecting groups that are not compatible with the zinc/acetic acid method.     

A Mild and Versatile Method for Carboxy Group Activation and Esterification

In his review of recent methods for the esterification and protection of carboxy groups, Haslam notes that a great need still exists for a versatile and simple process whereby esters may be formed under mild conditions.² It is appropriate, therefore, that we should disclose a straightforward and economical procedure which we have been using for the esterification of labile poly-function natural products, e. g. gibberellins and penicillins, and the preparation of allylic esters of dihydro-aromatic acids.     

N-heterocyclic carbene (thiamine) promoted eco-friendly synthesis of quinoxalines under mild reaction conditions

Abstract

An efficient and convenient protocol of broad scope for the synthesis of quinoxaline by cyclization-oxidation of phenacyl bromide with equimolar amount of phenylenediamine at room temperature catalyzed by thiamine in the form of N-heterocyclic carbene (NHC). High efficiency, inexpensiveness, and non-toxicity are the interesting features of the catalyst, which make it eco-friendly and highly attractive.     

An efficient microwave accelerated three component reaction of phenacyl azides and pyridinium phenacyl salts: A facile greener approach to 2-amino-2-ene-1,4-diones/pyrrolidin-2-ones

Abstract

A mild and efficient base promoted, microwave assisted, green synthesis of 2-amino-2-ene-1,4-diones has been described by the decomposition of phenacyl azides followed by treatment with pyridinium salts of phenacyl bromides in aqueous media. A diverse range of substrates bearing electron-releasing and electron-withdrawing substituents were well tolerated and delivered corresponding 2-amino-2-ene-1,4-diones in good yields. Synthesized 2-amino-2-ene-1,4-diones have been further explored in the synthesis of various substituted 4-hydroxypyrrolidin-2-ones.     

3-aryl(alkyl)quinazoline-2,4(1<Emphasis Type="Italic">H</Emphasis>,3<Emphasis Type="Italic">H</Emphasis>)-diones and their alkyl derivatives

Two-stage reaction of methyl anthranilate with aryl(alkyl) isocyanates in keeping with the quantumchemical calculations and XRD analysis resulted in 3-aryl(alkyl)quinazoline-2,4(1H,3H)-diones that by treatment with alkyl halides, phenacyl bromides, esters and amides of chloroacetic acid were converted into the corresponding 1-alkyl derivatives.     

Evaluation of Certain Pharmaceuticals with Dibromohydantion. V. Determination of Penicillins

Abstract

A new bromometric assay procedure for penicillins was developed, using an organic brominating agent. 1,3-Dibromo, 5,5-dimethylhydantion (DBH). The experimental conditions, the molar ratio as well as the identification of the reaction products were thoroughly studied. The end point could be detected visually or potentiometrically. Spectrophotometric titration could also be performed. The suggested procedure could be successfully applied to pharmaceutical preparations containing penicillins. The percentage recoveries for different penicillins were satisfactory.     

Über Reaktionen mit Betainen, 23. Mitt. Über Umsetzungen von N- und S-Betainen mit reaktiven Halogenverbindungen

Trimethylammonium acetic acid betain (1) reacts with phenacyl bromide and ethyl bromoacetate, respectively, to give the ester bromides2 and7. These can be hydrolyzed with aqueous sodium hydrogencarbonate at 20 °C to yield besides1 both C-benzoyl-methanol (3) and the glycolic acid ester8, respectively. The reaction can also be performed in one step by reacting the betain (1) (which can act as a base) in a double molar ratio with the active halide.

Herrn Prof. Dr.F. Asinger zur Vollendung des 80. Lebensjahres mit besten Wünschen gewidmet.     

Synthesis of Glycosylated Amino Acids for Use in Solid Phase Glycopeptide Synthesis,Part 2: N-(9-Fluorenylmethyloxycarbonyl)-3-0-[2,4,6-TRI-0-Acetyl-3-0-(2,3,4-TRI-0-Acetyl-α-D-Xylopyranosyl)-β-D-Glucopyranosyl]-L-Serine

Abstract

FMOC-serine phenacylester was glycosylated with a derivative of the disaccharide α-D-Xylp-(1→3)-β-D-Glcp, and the product was treated with zinc to remove the phenacyl group. The title derivative is useful for synthesis of blood clotting factor IX glycopeptide fragments by the solid-phase approach.