Reversed Phase Liquid Chromatography of Phenacyl Esters of Some Natural Penicillins

Abstract

The present work demonstrates a method by which natural, non-UV absorbing penicillins can be derivatized to form phenacyl esters. The reaction is rapid and essentially completed in twenty minutes. A straight line correlation was found between the peak height of a phenacyl ester derivative and the amount of the penicillin, a fact which attests to the applicability of the method for quantisation. The phenacyl esters of the penicillins studied here were separated on a reversed phase column.     

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.     

Regioselective alkylation of isopropylidene- and cyclohexylidenepropanedinitrile with phenacyl bromides

Alkylation of isopropylidene- and cyclohexylidenepropanedinitrile with phenacyl bromides gave 2,2-bis(2-aryl-2-oxoethyl)propanedinitriles. Direct alkylation of propanedinitrile with phenacyl bromides afforded only 2-(2-aryl-2-oxoethyl)propanedinitriles.     

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.     

Arylaliphatic 3-Aza-1,5-diketones: Reactions with N-Nucleophiles

1-Substituted 3,5-diphenylpyrazinium salts were obtained by reactions of tertiary bis(phenacyl)amines with ammonium acetate, hydroxylamine hydrochloride, and hydrazine hydrate in acid medium. The reaction of quaternary dimethylbis(phenacyl)ammonium bromide with hydrazine hydrate afforded 3,6-diphenylpyridazine.     

DABCO-Promoted Efficient and Convenient Synthesis of Benzofurans

An efficient and convenient synthesis of benzofurans has been described from phenacyl halides and o-hydroxy benzaldehyde in the presence of DABCO. The procedure is applicable for a variety of phenacyl halides and provide a variety of benzofurans. DABCO act as a base and as well as nucleophile.     

Stevens rearrangement of heterocyclic ammonium salts containing prop-2-yn-1-yl group

Stevens rearrangement was studied of ammonium salts where piperidinium or morpholinium groups are linked to prop-2-yn-1-yl moiety and labile hydrogen atom functions (methoxycarbonylmethyl, phenacyl, cyanomethyl). In the case of phenacyl analog furan derivatives were formed, in other cases dienamines were the reaction products.     

Imidazolium-Based Ionic Network as a Robust Heterogeneous Catalyst in Synthesis of Phenacyl Derivatives

A new imidazolium-based poly(ionic liquid) has been synthesized and used as a robust heterogeneous catalyst for the preparation of phenacyl derivatives by an S_N2 reaction of different phenacyl bromides with a broad range of nucleophiles. The products are obtained in high yields under mild conditions. The catalyst can be recycled efficiently.

     

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.     

Synthetic routes to 1,5-dihydro-5-oxo-4,1-benzoxazepines and to 5-oxooxazolo[3,2-a]quinolines

The literature concerning phenacyl anthranilate, N- phenacylanthranilic acid and phenacyl N-phenacylanthranilate is clarified. Phenacyl anthranilate is dehydrated to 1,5-dihydro-5-oxo-2-pheny 1-4,1-benzoxazepine by treatment with phosphoryl chloride; other examples of this reaction are described. A preparation of 4-methyl-5-oxo-2-phenyloxazolo[3,2-a]quinoline from N-phenacylanthranilic acid and propionic anhydride is reported.     

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.     

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.     

Phenacyl bromide: A versatile organic intermediate for the synthesis of heterocyclic compounds

Phenacyl bromides are used as a building blocks in synthetic organic chemistry, which serves as a key model for the development of various biologically important heterocyclic compounds and other industrially important scaffolds. This review covers recent synthetic advances in the preparation of heterocyclic compounds utilizing various phenacyl bromides. A wide range of five- and six-membered heterocyclic compounds as well as fused heterocyclic compounds were synthesized efficiently from the phenacyl bromide precursors through one-pot multicomponent reactions.     

Solvent effect on chemical shift non-equivalence of methylene protons in dibenzyl-, diphenacyl- and benzyl phenacyl sulphoxides

The methylene protons of dibenzyl sulphoxide are magnetically equivalent in low dielectric and non-equivalent in high dielectric constant solvents, while for diphenacyl sulphoxide this behaviour is reversed. In both cases, the variation in the magnitude of the non-equivalence reflects a greater downfield shift of one methylene proton than the other on passing from non-polar to polar solvents. By contrast, the chemical shift difference between the benzyl methylene protons or between the phenacyl methylene protons of benzyl phenacyl sulphoxide varies only slightly with solvent polarity.     

Phenacyl onium salt photoinitiators: synthesis, photolysis, and applications

Onium salts, namely sulfonium, phosphonium, ammonium, and pyridinium salts containing phenacyl group are photoinitiators appropriate for the polymerization of monomers such as oxiranes and vinyl ethers, which are not polymerizable by a free-radical mechanism. The initiation is accomplished by direct or indirect (sensitized) photolysis of the salts. Depending on the type of the salt, the direct photoinitiation of cationic polymerization involves reversible or irreversible processes. The photolysis of phenacylsulfonium compounds proceeds by a reversible process, while the other types undergo irreversible photolysis leading to complete fragmentation of the photoinitiator. An additionally useful tool, namely photosensitized generation of initiating species enlarges the versatility of these salts as photoinitiators. Photoinitiated free-radical and zwitterionic polymerizations by using phenacyl-type salts are also addressed. Keto-enol tautomerization of phenacyl pyridinium salts is discussed. Moreover, an interesting application concerning in situ synthesis of clay-poly(methyl methacrylate) nanocomposites with the aid of the phenacyl anilinium salt-based photopolymerization technique is noted.     

Synthesis and photochemical properties of novel multifunctional photopolymers with both pendant epoxy groups and phenacyl ester groups

Novel multifunctional photopolymers with both pendant epoxy groups and phenacyl ester groups were synthesized by the one‐pot method for the reaction of poly(methacrylic acid) with epibromohydrin; this was followed by a reaction with phenacylbromide with 1,8‐diazabicyclo‐[5.4.0]undecene‐7 as a condensation reagent. These esterification reactions proceeded smoothly and quantitatively under mild conditions. Moreover, the photochemical reactions of the resulting polymers were evaluated by UV and IR spectroscopy. The pendant phenacyl ester groups were photocleaved to give corresponding carboxyl groups, and then the produced carboxyl groups reacted with pendant epoxy groups. Furthermore, the baking process promoted a crosslinking reaction because of the addition reaction of epoxy groups with carboxyl groups after irradiation. It was also proven that the photochemical reactivity of the resulting polymers was affected by the structure of the phenacyl ester group. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 530–538, 2001     

Initiator selectivity during free radical copolymerizations of styrene and methyl methacrylate initiated by anaerobic copper(II) oxidation of carbon‐13 labeled acetophenone

Nuclear magnetic resonance (NMR) analysis of the ¹³C‐labeled chain ends of polystyrene, polyMMA, and styrene‐MMA copolymers prepared by polymerizations initiated using ¹³C‐labeled‐phenacyl radicals were investigated. The phenacyl radicals were generated by anaerobic oxidation of acetophenone‐methyl‐¹³C using a Cu(II) octanoate‐pyridine complex in the presence of triethylamine and triphenylphosphine. NMR analysis of the ¹³C‐labeled chain ends of these polymers afforded insight into the initiation mechanism. In copolymerization experiments using ¹³C‐labeled acetophenone initiator, the NMR spectra provided evidence that the phenacyl radical reacts 2.7 times faster with styrene than with MMA. The resonances of the labeled phenacyl carbons also showed that the sequence and stereosequence distributions of monomer units at the chain ends are nearly the same as those that prevail along the polymer chains. Styrene–styrene, styrene–MMA, and MMA–styrene enchainments at the chain ends are equally likely to have meso (erythro) or racemic(threo) configurations but the ratio of meso to racemic MMA‐MMA enchainments is ～ 3/7. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2347–2356, 2008     

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.     

CIDEP studies of the photolysis of the lignin model compound α-guaiacoxylacetoveratrone: the role of triplet reactions in aqueous and hydroxylic solvents

Free radical reactions induced by the photolysis of the lignin model compound α-guaiacoxylacetoveratrone have been studied by conventional and time-resolved ESR spectroscopy. In the presence of efficient hydrogen donors such as aqueous and hydroxylic solvents the primary reaction involves photoreduction of the triplet phenacyl ether to form the ketyl radical followed by rapid cleavage to the phenacyl radical and guaiacol. Subsequent formation of polarized guaiacoxyl radicals is due to secondary photo-oxidation. The cleavage of the ketyl radical is retarded in basic media and accelerated in acetic acid. Minor reaction pathways involving excited singlets cannot be ruled out by the current CIDEP observations.     

An efficient procedure for the synthesis of phenacyl and benzyl azolium salts using fluorous alcohols

An efficient procedure for the synthesis of phenacyl and benzyl azolium salts in 2,2,2-trifluoroethanol and 1,1,1,3,3,3-hexafluoroisopropanol as fluorous alcohols have been developed. This synthetic methodology has some advantages with the respect to yield, atom efficiency, solvent and reagents used and wastes generated when compared to the currently in use methods. Using this procedure, a range of phenacyl and benzyl azolium salts can be synthesized with good to excellent yields. The pure salts are separated from the reaction mixture by simple filtration and washing with dry ether.