Phenylethyl Groups Research Articles

Asymmetric synthesis of pipecolic acid derivatives using the aza-Diels-Alder reaction

Imines of the type RNCHCO 2Et can be coerced into undergoing a (4+2) cycloaddition with substituted dienes if the reaction is carried out in DMF in the presence of both water and acid: these reactions show extremely high regio- and diastereoselectivity. Use of the 1-phenylethyl group as a chiral auxiliary leads to moderate asymmetric induction (typical d.e. ca. 70%); moreover, the diastereoisomers are surprisingly easy to separate, giving a short general route to optically pure substituted pipecolic acid derivatives.

Tris(1-phenylethylcarbamate)s of Cellulose and Amylose as Useful Chiral Stationary Phases for Chromatographic Optical Resolution

Abstract (R)-, (S)-, and (RS)-1-phenylethylcarbamates of cellulose and amylose were synthesized and used as chiral stationary phases for high-performance liquid chromatography. The chiral recognition abilities of the 1-phenylethyl derivatives depended greatly on the chirality of 1-phenylethyl groups. Among six derivatives, amylose tris((S)-1-phenylethylcarbamate) showed high optical resolving ability for many compounds.

Antagonistes calciques. I. Remplacement du groupe diméthoxy-3,4 phényléthyle du vérapamil

In the verapamil structure, the 3,4-dimethoxy phenylethyl group has been replaced by several moieties belonging to α- and β-blockers or other classes of calcium channel blockers. The best derivatives, as calcium blockers, were prepared with β-blocker fragments like aryloxypropanolamines (AOPA) with an ortho substituent on the aromatic ring.

Reactivities of monomers towards the 1-phenylethyl radical: Monomers with low ceiling temperatures

The reactivities towards the 1-phenylethyl radical of 2-vinylnaphthalene and some monomers with low ceiling temperatures (α-methylstyrene, 2-isopropenylnaphthalene and α-methoxystyrene) have been assessed by 13C-NMR examination of end-groups in terpolymers prepared at 100° using 13C-enriched azobis-1,1′-phenylethane as initiator. In each case, acenaphthylene has been used with styrene (STY) or methyl methacrylate and a third monomer selected from the quoted list. The present and previous results suggest that, for many monomers, the reactivity towards the 1-phenylethyl radical is very similar to that predicted from data on copolymerizations with STY, regarding the initiating small radical as a model for the polystyrene radical. There are appreciable differences between the observed and predicted relative reactivities in cases where either the copolymerization of the monomer with STY may show quite pronounced penultimate group effects or the monomer has a low ceiling temperature.

Reactivities of monomers towards the 1-phenylethyl radical

The reactivities of styrene, methyl acrylate, methyl methacrylate, methyl isopropenyl ketone, methyl vinyl ketone and 2-vinylpyridine towards the 1-phenylethyl radical at 100° have been compared using acenaphthylene as the reference monomer. Binary copolymerizations with acenaphthylene were initiated by 1,1′[ 13C]azobis-1,1′-phenylethane; 13C-NMR spectroscopy was used to compare the numbers of initiator fragments attached to the two types of monomeric units in each of the various copolymers. The relative reactivities of the monomers towards the initiating radical match their relative reactivities towards the polystyrene radical, as deduced from monomer reactivity ratios for copolymerizations with styrene.

Retention of configuration in ligand coupling reactions in σ-sulphuranes

In accord with the ligand coupling concept, an axial and an equatorial ligand are considered to be extruded from the valence-shell-expanded heteroatom in a concerted fashion which thus affords the coupling product. Therefore, the coupling ligands should retain the original configuration. Indeed, the ligand coupling product, p-(1 -Phenylethyl)phenylsulphonylbenzene (3) formed in the reaction of 1 -phenylethyl benzene-p-sulphonylphenyl sulphoxide (2) with ethylmagnesium bromide is found to retain completely the 1 -phenylethyl group configuration, as in our earlier example of the coupling reaction of optically active 1 -phenylethyl 2-pyridyl sulphoxide with Grignard reagents and that of allylic and vinylic sulphoxides with Grignard reagents. The absolute configuration of (+)-(2) and (+)-(3) are determined unequivocally to be SsRc and Rc, respectively, by X-ray methods.

ChemInform Abstract: Photochemical Production of Peroxy Radicals and Their Interaction with Aromatic Alcohols.

The reaction between 1-phenylethyl peroxy radicals and 1-phenyl ethanol, benzyl alcohol and cumyl alcohol has been studied at T = 55°C. The rate coefficients of the hydrogen abstraction reactions for the three alcohols are 18.7 ± 2.7, 17.8 ± 1.9 and 4.8 ± 0.5 M−1 8−1, respectively. In the case of 1-phenyl ethanol experiments were carried out at T = 25 and 40°C as well, resulting in rate coefficients of 7.3 ± 0.7 and 10.5 ± 0.9 M−1 s−1, while the energy of activation — taking into consideration also the data of Hajdu et al. — was 27.7 ± 0.5 kJ mol−1.

X-ray analysis of the structure of the thermotropic copolyester poly[(phenyl- p-phenylene-terephthalate)-co-(1-phenylethyl- p-phenylene-terephthalate)

X-ray methods have been used to determine the structure of the thermotropic copolyester prepared from terephthaloyl chloride (TPA) and equimolar amounts of phenylhydroquinone (PHQ) and (1-phenylethyl) hydroquinone (PEHQ). The X-ray patterns of annealed melt spun fibres contain a series of sharp Bragg reflections, pointing to a well ordered crystalline structure, despite the random substitution of the phenyl and 1-phenylethyl groups on the polymer backbone. The unit cell is orthorhombic with space group P2 1 and dimensions: a = 12.77 A ̊ , b = 10.18 A ̊ , c = 12.58 A ̊ (fibre axis), and α = β = γ = 90° and contains TPA-PHQ or TPA-PEHQ units of four chains. The random substitution of phenyl and 1-phenylethyl groups was modelled by placing these groups at both the 2- and 3-positions of each hydroquinone and giving each a weight of one quarter. The structure was refined by linked atom least square methods against 13 observed and 26 unobserved reflections, and had a final R value of 0.25. Packing of the side chains is effected by staggering adjacent chains along the b axis by approximately c 2 , so that the side chains are interleaved. The phenyl-COO and COO-phenyl torsion angles are −5.3° and 65.4°, respectively, such that the main chain phenyls are mutually inclined at 60.1° (the ester groups are assumed to be planar). The phenyls of the phenyl-hydroquinone units are mutually inclined at 59.7° (ortho) and 60.1° (meta). These torsion angles compare very well with those for poly(phenyl- p-phenylene-terephthalate) reported earlier as well as those for model compounds, notably phenylbenzoate. This gives us confidence to use them in analyses of the structure of more complex random sequence copolyesters.

Pyrolysis behaviour of a styrene-ethylene (styrene-hydrogenated butadiene) copolymer

The degradation of a styrene-hydrogenated butadiene copolymer has been investigated by pyrolysis-gas chromatography (Py-GC) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). The copolymer was pyrolysed on a thermocouple-feedback-filament pyrolyser, and the products separated by means of capillary column GC. Pyrolysis products were identified by mass spectrometry, and correlated with copolymer composition and structure deduced from 13C NMR measurements. The principal pyrolysis products were styrene, phenylhexenes and styrene trimer. Many phenyl- and ethyl-substituted alkene fragments were also observed in the pyrogram, the latter being consistent with some 1,2-addition of butadiene in the original synthesis. The relative amounts of pyrolysis products are consistent with the copolymer structure deduced from NMR, i.e. the copolymer is almost random with a most probable sequence length of between 1 and 2 for both monomers, with occasional longer sequences. There was some evidence that thermal scission occurred preferentially at bonds adjacent to phenyl groups or ethyl groups. The formation of phenylhexenes was favoured; these probably result from intramolecular cyclisation reactions and also from intermolecular hydrogen transfer reactions. The fractional yield of phenylhexene is an indication of the styrene-butadiene dyads in the copolymer. The copolymer also evolves many isomeric fragments which are a result of 1,2-butadiene additions. It is shown that the resulting ethyl branches are then responsible for methyl-, as well as ethyl-substituted pyrolysis products which are observed in the pyrogram. Fairly high yields of styrene trimer were observed, especially at lower pyrolysis temperatures. It is suggested that monomer recombination reactions could be contributing to this.

Model copolymerization reactions. Initiation of the copolymerization of methyl methacrylate and acrylonitrile by 1,1′-azobis(1-phenyl[1- 13C]ethane)

The copolymerization of methyl methacrylate (MMA) and acrylonitrile (A) was initiated by photolysis of 1,1′-azobis(1-phenyl[ 13C]ethane) (1) at 33°C in benzene. Determination of relative endgroup concentrations in the resulting copolymers allowed determination of the relative rates of addition of MMA and A to the 1-phenylethyl radical derived from 1. We find k MMA/ k A = 0.44 ± 0.03, a value consistent with known copolymerization behavior. Further analysis of 75 MHz 13C NMR spectra led to the determination of k MMA/ k A for the 2-(4-phenylpentanenitrile) radical derived from primary radical addition to A. The measured value of k MMA/ k A supports only one of five reported studies of the radical copolymerization behavior of MMA and A.

Preparation of Optically Active Amphoteric Surfactants and Their Surface and Antimicrobial Properties

Racemic and optically active amphoteric surfactants, N-substituted amino acids and amino sulfates derivatives were prepared to determine relationship of physico-chemical relations of chiral isomers with chemical structures among chiral isomers. Amphoterics possess a 1-phenylethyl group as the hydrophobic chiral center. The racemates showed no difference with optically active isomers with respect to capacity for lowering surface tension and cmc. The influence of the long alkyl chain length of the hydrophobic group on cmc was essentially the same as that of other types of surfactants governed by Traube's rule, while the influence of chain length between the two hydrophilic groups could not be determined exactly. The pH of the solution affected the solubility of amphoterics and an aqueous solution of the amino acid derivative surfactants became turbid below pH 4 in acidic condition.The amphoterics were also tested for antimicrobial activity against bacteria and fungi. The hydrophobic long alkyl group significantly influenced antimicrobial activity more than the chiral isomerism. N-Dodecylated homologues were confirmed to be more antimicrobial than N-decylated homologues.

A method for the determination of the relative reactivities of monomers towards the 1-phenylethyl radical

Several monomers have been polymerized using 1,1′-azobis(1-phenyl [1- 13C] ethane as initiator; the initiator fragments incorporated in the polymers have been examined by 13C-NMR. The chemical shift for the enriched site in the end-group depends upon the nature of the attached monomeric unit. It is concluded that acenaphthylene is suitable as a reference monomer in comparisons of the reactivities of monomers towards the 1-phenylethyl radical (regarded as a model for the polystyrene radical) by consideration of end-groups in copolymers.

Synthesis and anticonvulsant activity of analogues of 4-amino-N-(1-phenylethyl)benzamide.

A group of amides and amines related to 4-amino-N-(1-phenylethyl)benzamide, 1, were prepared in a study on the relationship of structure to anticonvulsant activity in this compound. Acylation and alkylation of the amino group of 1 resulted in almost total loss of anticonvulsant activity. Insertion of a methylene between the 4-amino group and the aromatic ring of 1 produced a slight increase in anticonvulsant potency and a significant increase in toxicity. Hydride reduction of the amide carbonyl in 1 also yielded compounds having a slightly lower ED50 against convulsions induced by electroshock and a much lower TD50 in the rotorod assay. Modification of the 1-phenylethyl group of 1 also decreased anticonvulsant potency.

Effect of a magnetic field on the photoracemization of optically active ?-methyldesoxybenzoin

1. A magnetic field decreases the efficiency of photoracemization ofα-methyldesoxybenzoin by 20%; this is evidence for a radical mechanism of racemization. 2. The recombination probabilities of triplet radical pairs in micelles and their dependence on magnetic field intensity were measured. 3. The probability of disproportionation of the pair of benzoyl and 1-phenylethyl radicals is ∿4.5 times less than the probability of their recombination; this ratio of probabilities is independent of the magnetic field.

Model copolymerization reactions. Determination of the relative rates of addition of styrene and acrylonitrile to the 1-phenylethyl radical

2,2'-Azobis([2-^(13)C]propionitrile) (1) was prepared in 35% overall yield starting from [^(13)C]-acetaldehyde (99 atom %). Quantitative ^(13)C NMR analysis of end groups in styrene-acrylonitrile copolymers prepared with 1 as initiator allows determination of the relative rates of addition of these olefins to the 1-cyanoethyl radical. We have found k_A/k_s = 0.12 ± 0.03, a result consistent with the penultimate model treatment of this copolymerization system by Hill, O'Donnell, and O'Sullivan.

Deuterium isotope effects in carcinogenesis by N-nitroso compounds.

A number of N-nitroso compounds and an azoxyalkane have been labeled with deuterium in various positions and have been administered to rats, hamsters, or mice in parallel with the unlabeled compounds. The treatments with the labeled and analogous unlabeled compounds were equimolar and for the same time. Mortality rates from tumors and tumor incidences were compared between deuterium-labeled and the unlabeled analogs. In many cases more than one dose level was used for the comparisons. An increased rate of mortality from tumors or an increased incidence of induced tumors was considered an index of increased potency of one treatment compared with the other. Using these criteria deuterium in the alpha positions of nitrosodimethylamine, nitrosomorpholine, nitrosoheptamethyleneimine, and nitrosoazetidine reduced carcinogenic potency compared with the unlabeled compounds. This indicated that cleavage of a carbon-hydrogen bond in the alpha position was a rate-limiting step in carcinogenesis by these nitrosamines. In both nitrosomethylethylamine and nitroso-2,6-dimethylmorpholine, the presence of deuterium at different positions increased or decreased carcinogenic potency, suggesting that competition for oxidation between these sites might be the determining factor in activation of the molecule. This also applied to nitrosomethyl-n-butylamine and nitrosomethyl-phenylethylamine with deuterium at the methyl group or at the alpha carbon of the butyl or phenylethyl groups, and to azoxymethane with deuterium in the 1-methyl or 4-methyl group. In nitrosomethylcyclohexylamine, nitrosomethyl-n-dodecylamine, and dinitroso-2,6-dimethylpiperazine there was no detectable effect of deuterium on carcinogenic potency, suggesting that the conditions did not provide sufficient sensitivity for detection of an isotope effect, or that oxidation at the alpha carbon was not a rate-limiting step in carcinogenesis by these molecules.

ChemInform Abstract: Hydrogen Abstraction by Hydrocarbon Radicals. Part 1. Interactions Between 1‐Phenyl Ethyl Radicals and 1‐Phenyl Ethanol as Well as Benzyl Alcohol

Chemischer InformationsdienstVolume 17, Issue 38 Preparative Organic Chemistry ChemInform Abstract: Hydrogen Abstraction by Hydrocarbon Radicals. Part 1. Interactions Between 1-Phenyl Ethyl Radicals and 1-Phenyl Ethanol as Well as Benzyl Alcohol A. GEDRA, A. GEDRASearch for more papers by this authorJ. LUKACS, J. LUKACSSearch for more papers by this authorT. VIDOCZY, T. VIDOCZYSearch for more papers by this authorL. + SUEMEGI, L. + SUEMEGISearch for more papers by this authorD. GAL, D. GALSearch for more papers by this author A. GEDRA, A. GEDRASearch for more papers by this authorJ. LUKACS, J. LUKACSSearch for more papers by this authorT. VIDOCZY, T. VIDOCZYSearch for more papers by this authorL. + SUEMEGI, L. + SUEMEGISearch for more papers by this authorD. GAL, D. GALSearch for more papers by this author First published: September 23, 1986 https://doi.org/10.1002/chin.198638108Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume17, Issue38September 23, 1986 RelatedInformation

Radical polymerization initiated by primary radicals with similar structure to the end radical on the polymer

1,1′-Azobisethyl-1-phenylethane and dimethyl-2,2′-azobisisobutylate decompose to yield 1-phenylethyl radical (PER) with a similar structure to the end radical on polystyrene (ST) and 1-methyl-1-methylcarboxylate ethyl radicals with that of poly(methylmethacrylate) (MMA). The data on the polymerizations of ST and MMA initiated by the above primary radicals at 60°C are treated by using some equations obtained before. Rate constants of termination between small polymeric radicals such as the primary radicals are estimated to be k ̄ tST: ST = 5.2 × 10 8l mol −1 s −1 and k ̄ tMMA: MMA = 1.1 × 10 8 . A rate constant of primary radical termination between PER and polyMMA radical is also estimated to be k ̄ ti = 3.1 × 10 8 ( ⋍ k ̄ tST: MMA ). From these values, k ̄ tST: MMA ( k ̄ tST: ST k ̄ tMMA: MMA ) 1 2 is calculated to be 1.3, which is close to unity. However, it differs from ø ⋍ 13 obtained before for cross-termination in polymerization between ST and MMA.

Ligand coupling through σ-sulfurane — complete retention of configuration of 1-phenylethyl group in the reaction of 1-phenylethyl 2-pyridyl sulfoxide with grignard reagent1

Abstract The reaction of benzyl or 1-phenylethyl 2-pyridyl sulfoxide with Grignard reagent proceeds via a σ-sulfurane as an intermediate to give the coupling product, 2-benzylpyridine or 2-(1-phenylethyl)pyridine in quantitative yield. Stereochemistry for this reaction is complete retention at the benzylic carbon atom.

Identification of fendiline metabolites in human urine.

After oral application of 14C labelled fendiline, 13 metabolites of this drug could be identified in human urine. Only traces of parent fendiline were excreted in the urine. The main pathway of metabolism is hydroxylation of phenyl groups with subsequent glucuronidation and sulphation. On the other hand, oxidative dealkylation occurs with the amino group remaining at the 3,3-diphenylpropyl moiety and p-hydroxyacetophenone being formed almost entirely from the 1-phenylethyl group.