Phenacyl Esters Research Articles

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.

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.

Phenacyl esters of acetic acid derivatives and their application for the synthesis of 2‐oxo‐4‐phenyl‐5‐(phenylhydrazono)‐2,5‐dihydro‐furan‐3‐derivatives

Abstractmagnified imageCoupling of various substituted phenacyl acetates 1 and diazonium salts 3 was studied. If the phenacyl acetates were substituted by an electronaceptor group such as CN or COOEt 3‐substituted phenyl‐5‐(phenyl‐hydrazono)‐5H‐furan‐2‐ones 4 were formed. Also synthesis of aza and diaza analogs is described. The compounds were characterized using MS and NMR spectroscopy.

Positional isomers of thienopyrimidinones

Condensation of o-cyanomethylbenzoic acids with esters of 2-aminothiophene-3-carboxylic and 3-amino-thiophene-2-carboxylic acids to give isomeric 2-(4-oxo-3,4-dihydrothieno[2,3-d]pyrimidin-2-ylmethyl)-benzoic acids and their ethyl and phenacyl esters. Methylation of esters occurs at N-3. The spectroscopic characteristics of the positional isomers are compared at the level of carboxylic acids, their esters, and methylated products.

Analysis of Phenacylester Derivatives of Fatty Acids from Human Skin Surface Sebum by Reversed-Phase HPLC: Chromatographic Mobility as a Function of Physico-Chemical Properties

A set of 13 fatty acids was transformed into their phenacyl esters by reaction withphenacyl bromide in acetonitrile using 18-crown-6 as phase-transfer catalyst. Conditions forthe RP-18 HPL chromatographic separation of most of the esters has been worked out.Using this standard the fatty acid spectra from skin surface sebum lipids of 17 test personswas taken after microwave-assisted hydrolysis, neutralization and extraction with n-hexane.Quantitative evaluation of the chromatograms exhibits that oleic acid predominates in thesebum of all test persons. In the second part of the work the chromatographic mobility (REvalues) of fatty acid phenacyl esters is correlated with calculated physico-chemicalparameters of the corresponding acids. The best linear correlation was found between the REand the logP values. This is helpful for the structural elucidation of un-identified fatty acidsin a chromatogram.

Efficient Solid-Phase Synthesis of 2-Substituted-3-Hydroxy-4(1H)-Quinolinone-7-Carboxamides with Two Diversity Positions

A highly efficient solid-phase synthesis of 2-substituted-3-hydroxy-4(1H)-quinolinone-7-carboxamides was developed using anthranilates and bromoketones as the key synthons. Primary amines immobilized to an acid-cleavable BAL linker were acylated with 1-methyl-2-aminoterephtalate. After cleavage of the methyl ester, bromoketones were used to form resin-bound phenacyl esters. Acid-mediated cleavage and subsequent cyclization in solution afforded 3-hydroxy-4(1H)-quinolinones in high purity and yield. Highly efficient solid-phase synthesis (purity>90%, yield>80%, synthetic time=2 days using commercially available synthons) is amenable to high-throughput/combinatorial synthesis to match the high-throughput screening capability.

1-Oxoindan-2-yl and 1,3-dioxoindan-2-yl esters as photoremovable protecting groups

1-Oxoindan-2-yl and 1,3-dioxoindan-2-yl carboxylic acid esters react with an excess of hydrogen atom or electron donors to release the corresponding acids, in addition to indan-1-one and indan-1,3-dione, respectively, as by-products. The maximum degradation quantum yields of 1-oxoindan-2-yl esters in H-donating propan-2-ol were found to approach 10, indicating that a chain reaction process, involving hydrogen transfer from the ketyl radical intermediates formed from an excited ester by hydrogen abstraction from an alcohol, participates. Such a cleavage mechanism parallels that observed earlier in photolysis of phenacyl esters. The corresponding 4,7-dimethyl substituted derivatives showed no contribution of the photoenolization mechanism apparently because of electronic and geometric reasons. Both 1-oxoindan-2-yl and 1,3-dioxoindan-2-yl chromophores are proposed to be utilized as photoremovable protecting groups in applications when higher concentrations of the hydrogen/electron donors are experimentally feasible.

Analysis of Western Redcedar (Thuja plicata Donn) Heartwood Components by HPLC as a Possible Screening Tool for Trees with Enhanced Natural Durability

A method is described for the quantitative analysis of seven known compounds, specifically plicatic acid, thujaplicatin methyl ether, beta-thujaplicin, gamma-thujaplicin, beta-thujaplicinol, thujic acid, and methyl thujate, in the ethanol extract of second growth western redcedar heartwood (Thuja plicata Donn) by high-performance liquid chromatography using diode array detection. The para bromo phenacyl ester of crotonic acid is synthesized for use as the internal standard for the method. Separation of compounds covering a wide range of polarities is achieved using an Inertsil ODS 3 3-micro column. Twenty seven second growth trees ranging in age from 40 to 125 years, originating from the coastal and interior regions of British Columbia, are selected for analysis and profiled using the described method. Samples consisting of five growth rings each are analyzed from the heartwood-sapwood boundary to the pith for each tree. Substantial variation in most heartwood compounds are detected within and between trees within a region. Significant variation in beta-thujaplicin, the ratio between gamma- and beta-thujaplicin, and methyl thujate is detected between coastal and interior populations.

A Quantitative Method for the Determination of Cyclopropenoid Fatty Acids in Cottonseed, Cottonseed Meal, and Cottonseed Oil (Gossypium hirsutum) by High-Performance Liquid Chromatography

Cyclopropenoid fatty acids (CPFAs), found in cottonseed, have been shown to have detrimental health effects to susceptible livestock. Previous quantitative analytical methods for the determination of CPFAs expressed these acids in terms of their relative abundance with respect to other fatty acids in the oil, necessitating the concurrent analysis of other fatty acids. The proposed analytical method describes the quantitation of three relevant CPFAs for cotton (malvalic acid, sterculic acid, and dihydrosterculic acid) in cottonseed in micrograms per gram fresh weight of sample. The method involves extraction of the oil, saponification, and derivatization of the free fatty acids with 2-bromoacetophenone to give the phenacyl esters. These esters are then separated by dual-column reverse-phase high-performance liquid chromatography and quantitated via external standards. This is the first method to include external calibration standards for CPFAs and, as such, is capable of direct quantification with no further data conversion required. CPFA data generated from the analysis of cottonseed, cottonseed meal, and cottonseed oil produced in the United States in 2002 are presented.

Enzymatic Removal of Carboxyl Protecting Groups. III. Fast Removal of Allyl and Chloroethyl Esters by Bacillus subtilis Esterase (BS2)

An esterase from Bacillus subtilis (BS2) allows the fast and selective removal of allyl, 2-chloroethyl, and 2,2,2-chloroethyl esters under mild conditions in high yields. In addition, BS2 easily hydrolyzes phenacyl esters, while the hydrolysis of sterically hindered diphenylmethyl esters is slow, requiring longer reaction time and higher enzyme/substrate ratio.

Synthesis of 4-(Fmoc-aminoacyloxymethyl)phenoxyacetic Acids for Use in Solid-Phase Peptide Synthesis

The synthesis of 4-(Fmoc-aminoacyloxymethyl)phenoxyacetic acids was achieved in high yield by the reaction of Fmoc-amino acids with (4-iodomethylphenoxy)acetic acid 2-oxo-2-phenylethyl ester. The removal of the temporary protecting group, phenacyl ester, was effectively achieved by reductive cleavage with magnesium turnings.

Chain Mechanism in the Photocleavage of Phenacyl and Pyridacyl Esters in the Presence of Hydrogen Donors

[reaction: see text] Excited phenacyl and 3-pyridacyl esters of benzoic acid react with an excess of aliphatic alcohols in a chain reaction process involving hydrogen transfer from the ketyl radical intermediates, leading to benzoic acid in addition to acetophenone and 3-acetylpyridine, respectively, as the byproducts. While the maximum quantum yields reached 4 in both cases, the 2- or 4-pyridacyl ester photoreduction proceeded with the efficiency below 100% under the same conditions. The investigation indicates that a radical coupling between ketyl radicals, both formed from the excited ester by hydrogen abstraction from an alcohol, is accompanied by the elimination of benzoic acid from the ester ketyl radical itself. A partitioning between two reactions was found to be remarkably sensitive to the chromophore nature, such as a position of the nitrogen atom in the pyridacyl moiety. The magnitude of a radical chain process is dependent on the efficiency of consecutive steps that produce free radicals capable of a subsequent ester reduction. The driving force of a possible electron transfer from the ketyl radicals to the ester has been excluded on the basis of cyclic voltametry measurements. The observed quantum yields of photoreduction were found to be diminished by formation of relatively long-lived light absorbing transients, coproducts obtained apparently by secondary photochemical reactions. Additionally, it is shown that basic additives such as pyridine can further increase the efficiency of the photoreduction by a factor of 4. A radical nature of the reduction mechanism was supported by finding a large kinetic chain length of an analogous reaction initiated by free radicals generated thermally yet again when phenacyl or 3-pyridacyl benzoate was used. Both phenacyl and pyridacyl chromophores are pronounced to be valuable as the photoremovable protecting groups when high quantum and chemical yields of carboxylic acid elimination are important, but higher concentrations of the hydrogen atom donors are not destructive for a reaction system or are experimentally impractical.

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

AbstractFor Abstract see ChemInform Abstract in Full Text.

Double use of microwaves in fatty acid preparation for elaidic acid determination as phenacyl ester using high-performance liquid chromatography in Brazilian fat products

Brazilian samples of fat products like margarines, butters and chocolates were prepared to reversed-phase high-performance liquid chromatography analysis, using a domestic microwave oven for fat hydrolysis and derivatization with phenacyl chloride. The total reaction time was 6 min, recoveries were above 94%. Total reproducibility for whole procedure were 3.5% R.S.D. for elaidic acid ( n = 3), the total chromatography analysis was 25 min.

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

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. IICT Communication 050211.

Phenacyl esters as a new photocleavable linker in liquid-phase chemistry

PEG-supported 2-methylphenacyl ester as a new photocleavable linker is reported. The photocleavage based on an efficient intramolecular hydrogen abstraction was carried out with 280–366 nm UV irradiation in benzene or methanol to give the corresponding carboxylic acid in high yields and purities. The linker was suitable for aliphatic and aromatic carboxylic acids as well as protected amino acids.

Capillary electrophoretic analysis of dimethylsulfoniopropionate in sugarcane and marine algal extracts

A simple and high-resolution analytical method for the determination of dimethylsulfoniopropionate (DMSP) in sugarcane and marine algae is described. Effective extraction of DMSP from plant samples was also investigated using organic solvents, 5% perchloric acid or deionised water. To increase the sensitivity, DMSP in the extracts was first converted to a phenacyl ester, and the reaction mixture was applied directly to capillary electrophoresis without any pretreatment. Water extraction followed by esterification in a pH 4 reaction buffer was found most suitable for the measurement of alkaline-labile DMSP. This method was applied to the determination of DMSP levels in marine algae samples collected from the seashore of Nagasaki, Japan. An increase in DMSP content in Ulva pertusa in the winter period was observed.

Chemoselective Alkylation of 3‐ and 4‐(5‐Amino‐4‐hetaryl‐2,3‐dihydro‐3‐oxopyrrol‐1‐yl)benzoic Acids.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Chemoselective Alkylation of 3- and 4-(5-Amino-4-hetaryl-2,3-dihydro-3-oxopyrrol-1-yl)benzoic Acids

Alkylation of 3- and 4-(5-amino-4-hetaryl-2,3-dihydro-3-oxopyrrol-1-yl)benzoic acids with phenacyl bromides or chloroacetanilides in DMF in the presence of triethylamine occurs at the carboxy group with high selectivity and yields the corresponding phenacyl and arylcarbamoylmethyl esters. The initial pyrrolylbenzoic acids were synthesized by reaction of 3- and 4-aminobenzoic acids with 4-chloro-2-hetaryl-3-oxo-butyronitriles.

Direct mass spectrometric monitoring of solid phase organic syntheses.

Direct on-bead monitoring of solid-phase reactions is possible with soft laser desorption time-of-flight mass spectrometry (SLD-TOF MS) without prior cleavage from the resin if photocleavable phenacyl ester or o-nitroveratryl linker groups are employed.