Α-phenylethyl Amine Research Articles

Conformational distortion of α-phenylethyl amine in cryogenic matrices - a matrix isolation VCD study.

The chiral amine α-phenylethyl amine (PEA) was isolated in cryogenic matrices and investigated using vibrational circular dichroism (VCD) and infrared spectroscopy. The potential energy surface (PES) of PEA features five different conformers connected by relatively low conformational transition states. Based on the IR spectra, it could be confirmed that all conformational energy barriers are passed at a deposition temperature of 20 K, and that only the global minimum conformation of PEA is populated in both argon and nitrogen matrices. However, differences in the calculated and experimental VCD spectra indicate deviations from the minimum structure by perturbation of the phenyl ring as well as of the amine orientation. The degree of the perturbation is found to also depend on the choice of the host gas, which shows the subtle influence of the environment on the conformational distortion of PEA.

Novel 1,10-diaza-18-crown-6 derivatives

Reaction of 1,10-bis(methoxymethyl)-1,10-diaza-18-crown-6 (1) with trimethylsilyl azide resulted in hitherto unknown 1,10-bis(azidomethyl)-1,10-diaza-18-crown-6 (2) and novel ionic compound 1,10-bis(azide anion)-1,10-dihydro-1,10-diaza-18-crown-6 (3). Compound 2 rnneacted with dimethyl acetylenedicarboxylate to give 1,10-bis(4,5-dimethoxycarbonyltriazolomethyl)-1,10-diaza-18-crown-6 (4). Carbamoylation of 1,10-diaza-18-crown-6 (5) with optically active α-phenylethyl amine yielded optically active 1,10-bis(α-phenylethylcarbamoyl)-1,10-diaza-18-crown-6 (6).

Study of stereomeric peptoid chiral stationary phases containing different chiral side chains

In this study, we investigated six stereomeric peptoid chiral stationary phases (CSPs) successively combining N′-phenyl-proline amide, α-phenylethyl amine, 2-aminocyclohexyl phenylcarbamate and another α-phenylethyl amine under normal phase mode. CSPs 1–4 with R-S-(R,R)-S, R-S-(S,S)-S, R-R-(R,R)-R and R-R-(S,S)-R configuration exhibited much different enantiorecognition abilities. Overall, CSPs 1 and 2 performed better for the 55 analytes tested. CSP 5 with mixed selectors combined partial selectivities of CSPs 1 and 2. CSP 6 as enantiomeric counterpart of CSP 2 exhibited similar enantioseparation ability and reversal elution orders for analytes resolved. For several biaryl type analytes, CSP 6 even outperformed commercial Chiralpak AD-H and Chiralcel OD-H. Excellent resolution of 3,3′-diphenyl-2,2′-bi-1-naphthalol (VANOL) on CSP 6 illustrated its potential application in preparative enantioseparation. Eluting orders of enantiomers on stereomeric CSPs also provided us further insight into enantiorecognition of some analytes.

Chiral chemical absorption property of a cross‐linked poly(N‐isopropyl acrylamide‐co‐sodium acrylate) thermoresponsive smart gel

This investigation leads to the chiral chemical absorption property of a thermoresponsive gel material. D-(+)-α-phenyl ethyl amine was taken as the chiral chemical. The gel material was synthesized by polymerizing 1:1 mole ratio of N-isopropyl acrylamide and Na-acrylate along with methylene bisacrylamide (2 wt.% of total monomer) as a cross-linker using ammonium persulfate as an initiator and N, N, N', N'-tetra-methyl ethylene diamine as an accelerator. The microporous nature of the gel material is observed by scanning electron microscope as well as by surface analysis. It is a pH as well as thermoresponsive gel. The highest gel swelling is observed at around pH 8.2 at room temperature (30 °C). The gel contains carboxylate (-COO(-)) group in this slightly alkaline condition. In the ionic state, the mutual repulsion of the ionic groups helps in swelling the gel. The lower critical solution temperature (LCST) of the gel is observed to be about 38 °C, which is higher than that of poly N-isopropyl acrylamide itself (32 °C). This corroborates with the theory and other reported results that LCST increases with the incorporation of ionic moiety in the cross-linked copolymer. The chiral chemical absorption of the gel material was monitored by measuring circular dichroism of the chiral compound in the presence and absence of gel using a circular dichroism spectropolarimeter (J-810 L) (JASCO International Co., Ltd., Tokyo, Japan). About 18% of D-(+)-α-phenyl ethyl amine is absorbed from its aqueous solution by 0.01 g of dry gel material (particle size: 106-212 µm) at room temperature. The absorption of the chiral compound is reversible with temperature having a sudden jump at LCST (38 °C) of the gel material.

Facile Synthesis of New Optically Active Unsaturated Amides Monomers Based on S-(+)-α-Phenyl Ethylamine

Three new optically active unsaturated amides monomers which could be polymerized were synthesized through the direct condensation between S-(+)-α-phenyl ethylamine and prop-2-enoyl chloride, 2-methyl-prop-2-enoyl chloride and undec-10-enoyl chloride, respectively. The resulted unsaturated amides were proven by means of 1H-NMR spectroscopy, FT-IR spectroscopy, elemental analyses and specific rotations. The polymerization of one of synthesized monomers, N-(1S-1-phenylethyl)-undec-10-enamide, is reported for the first time.

Immobilized lipase YlLip2-catalyzed resolution of (±)α-phenylethyl amine in a medium with organic cosolvent

In this paper, we studied the enantioselective aminolysis activity of an immobilized extracellular lipase LIP2 (YlLip2) from Yarrowia lipolytica by catalyzing enantioselective acylation of (±)α-phenylethyl amine with acetic ester in a medium containing cosolvent. The reaction parameters including cosolvent concentration, reaction temperature, amount of the immobilized lipase and the reaction time were optimized. When the reaction was carried out in hexane with the presence of 3% DMSO and six pieces of immobilized lipase at 45 °C for 6 days, the enantiomeric excess of product ( e.e.p) markedly increased from 0.35 (in neat hexane) to 0.96 and the enantiomeric ratio ( E) improved from 2.5 (in neat hexane) to 190. The immobilized lipase could be reused at least five consecutive batches at high E (≈190).

Stereoselective Reaction Mass Spectrometry with Cyclic α-Amino Acids

Stereoselective reaction mass spectrometry in the chemical ionization (isobutane) mode has been used to detect the absolute configuration of enantiomerically pure cyclic α-amino acids. Thus, an enantiomerically pure cyclic α-amino acid was allowed to react on a micromole level with both enantiomers of a chiral selector and the mass spectra were detected. The relative abundances of characteristic ions formed by the diastereoselective reaction between the α-amino acid and the chiral selector of the same configuration were much higher than those ions formed by the α-amino acid and the chiral selector of a different configuration. The absolute configuration of the α-amino acid may be predicted by careful examination of the two stereoselective reaction mass spectra of the α-amino acid measured with both, the chiral (R)-and (S)-selector respectively. Various (R)- and (S)-carboxylic acids and (R)- and (S)-α-phenylethyl amine have been used as chiral selectors.

Stereoselective adduct formation of α-acylcamphorato-copper(II) chelates with some chiral Lewis bases

The formation constants of the mono-adducts of α-acylcamphorato-copper(II) chelates such as (+)-Cu(facam) 2, (−)-Cu(facam) 2, (+)-Cu(hfbc) 2 and (−)-Cu(hfbc) 2 with some chiral Lewis bases were determined spectrophotometrically in benzene. In order to compare the adduct formation constants obtained with the (+)- and (−)-forms, some pairs of chiral Lewis bases such as 1-amino-2-propanol [( R)(−), ( S)(+)], 1-(α-naphthyl)ethylamine [( R)(+), ( S)(−)], α-phenyl ethylamine [( R)(+), ( S)(−)] and also quinine and quinidine were examined as neutral ligands. Although not very pronounced, the effects of combinations obtained for (+)- or (−)-Cu(II) chelates and (+)- or (−)-ligands indicate that formation constants obtained by the formation of adducts with the ligands having different directions of the optical rotation seems to be superior to those with the same direction.

Reaction of catalytic enantioselective reductive aminolysis of δ 2-oxazolin-5-ones as a method of asymmetric synthesis of α-amino acids

This investigation is devoted to the interaction of Δ 2-oxazolin-5-ones, S(—)-α-phenylethy lamine and H 2 in the presence of PdCl 2 which yields α-phenylethylamides of acylamino acids of the S,S configuration, hydrolysis of the latter compounds resulting in the formation of optically pure amino acids and providing for chiral amine recycling. In DME, double bond saturation and ring opening in Δ 2-oxazolin-5-one occur within the catalytic complex sphere without the intermediate formation of saturated oxazolinones or unsaturated amides. In t-BuOH, saturated oxazolinones are formed as intermediates. The catalyst formed in situ was shown to be a zero-valent Pd complex with S(—)-α-phenylethylamine stabilized by substrate coordination. The stereochemical pathway of the reactions has been traced. Reductive aminolysis involves cis-addition of H 2, while in reductive methanolysis H 2 trarns-addition occurs. The suggested process mechanism accounts for the ratio of aminolysis and racemization rates for saturated oxazolinones and the ratio of diastereomers of α-phenylethylamides of acylamino acids obtained by reacting unsaturated Δ 2oxazolin-5-ones with S(—)-α-phenyl-ethylamine. In agreement with the postulated mechanism, the catalyst enantioselectivity is observed at the steps of substrate addition to the catalyst and proton transfer to the α-C-center, provided the process is carried out in DME. In the case of t-BuOH, the enantiodifferentiating action of the catalyst vanishes as a result of racemization, and process stereo selectivity appears at the step of saturated oxazolinone aminolysis with a chiral amine.

Asymmetrical nonbridgehead nitrogen—XXIII: Chiral 3,3-bis(trifluoromethyl)diaziridines

By means of the reaction of O-tosyloxime 1a with propargyl amine, esters of glycine and ( S)-α-alanine, β-acetoxyethyl amine and β-dimethylaminoethyl amine functionally substituted 3,3- bis(trifluoromethyl)diaziridines 2a–g have been obtained. In the reactions with more bulky amines, ( S)-phenylalanine Et ester, ( R, S)-α-phenylethyl amine and t-butyl amine, 1a acts as a tosylating reagent. The ester group in diaziridine 2e is readily saponified by alcoholic alkali, whereas diaziridine 2c is rearranged in these conditions with ring-expansion. Complete asymmetric transformation has been found to take place on the formation of the solid phase of diastereomers 2d and 2j, and a closed cycle of diastereomeric transformations has been accomplished. Diaziridine 2g with chiral centres only at the nitrogen atoms has been obtained with the optical purity of 85.5% by resolution via salt 5c with d-(+)-camphor-3-carboxylic acid. The absolute configuration of (+)- 2g and its quaternary salt, (+)- 2h, has been determined from CD spectra. Optically active (−)- 2h salt (optical purity 2.0%) has been also obtained by asymmetric synthesis on the basis of 1–10-camphorsulphonyl oxime 1b. From the kinetics of 2g, h racemization and 2d, e, i, j, k epimerization the energy parameters of the inversion of N atoms in 3,3- bis (trifluoromethyl)diaziridines have been determined.

Asymmetric radical polymerization of N-butadiene 1-carboxylyl S(−)- α-phenyl ethyl amine

N-butadiene 1-carboxylyl S(−)- α-phenyl ethyl amine (Bu-1-CPA) was prepared and polymerized in various solvents such as acetonitrile, dimethylformamide (DMF), methanol, dioxane and benzene at 50° using AIBN as initiator. From the i.r. spectra of the polymers, it was confirmed that poly(Bu-1-CPA) was composed of trans 1,4-units. The polymer produced in DMF showed constant optical activity around [ α] D − 10° ( c = 1.0 in DMF) but the polymers obtained in the other solvents showed different optical activity, suggesting that the degree of asymmetric induction depended upon the solvent used during polymerization. From results for the copolymerization of Bu-1-CPA with styrene, it was similarly found that the asymmetric induction occurred in the backbone chain. The proposed mechanism for asymmetric induction involves polymerization via amide-iminol type prototropic tautomerism of Bu-1-CPA.