Polymeric Pd catalysts for the reduction of acetamidocinnamic acid azlactone and its solvolysis products

Pd complexes have been obtained from linear and cross-linked copolymers ofR,S-, R-, andS-1-(4-vinylphenyl)ethylamine (1) with styrene and divinylbenzene. Reduction of these compounds gave catalysts which were active in the reductive solvolysis of -acetaminocinnamic acid azlactone (2) and hydrogenation of the solvolysis products -acetamidocinnamic acid (ACA), its esters, and its 1-phenylethylamide. The catalysts showed no enantioselective properties in the reductive hydrolysis, but were more active than the catalyst obtained in the absence of the polymer (the monomeric analog). The use of polymeric catalysts has shown that, in reductive aminolysis, the chiral nucleophile plays the dominant part in determining the stereoselectivity of the reaction, rather than the chiral ligand of the catalytic complex. The polymer matrix stabilizes the low-valent state of the palladium in the complex. In the hydrogenation of ACA and its esters, the catalyst on the cross-linked polymer is much more active than its monomeric analog, but showed no enantioselectivity. Hydrogenation of acetamidocinnamic acidR-andS-1-phenylethylamides on a chiral Pd-polymer catalyst occurred with double asymmetric induction.Deceased.N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, 117913 Moscow. A. V. Topchiev Institute of Petrochemical Synthesis, Russian Academy of Sciences, 117912 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 10, pp. 2368–2380, October, 1992.     

Filter Diagonalization with Finite Fourier Transform Eigenfunctions

Below, we briefly report on the progress in the development of the Filter Diagonalization technique when filtering is carried out with the aid of Finite Fourier Transform (FFT) eigenfunctions. During recent years interest in these functions, also known as ‘prolates’, or ‘slepians’, has increased among scientists doing research in the field of signal processing. The main explanation to this follows from the set of very special extremal and orthogonality properties exibited by the FFT eigenfunctions. Recent results of Walter and Shen on sampling with prolate spheroidal functions will necessary produce a new wave of interest. In the presented, Filter diagonalization machinery, we show that the sampling formula of Walter and Shen simplifies essentially the computation of matrix elements as certain 2D–integrals involving FFT eigenfunctions.     

The effects of sample preparation methods on the variability of the electrospray ionization response for model drug compounds

A post-column infusion system was developed in order to analyze suppression of electrospray ionization (ESI) tandem mass spectrometry response in the presence of endogenous plasma interferences. By enabling direct detection of these interfering components, this experimental system was used to analyze the ability of several common extraction procedures to remove endogenous plasma components that cause changes in the ESI response of model drug substances. Methyl-t-butyl ether (MTBE) liquid-liquid, Oasis and Empore solid-phase, and acetonitrile (ACN) protein precipitation sample preparation methods were tested using the post-column infusion system. In all cases, ACN protein precipitation samples showed the greatest amount of ESI response suppression while liquid-liquid extracts demonstrated the least. In addition, the three test compounds, phenacetin, caffeine, and a representative Merck compound, demonstrated that ESI response suppression is compound dependent. Suppression was greatest with caffeine, the most polar analyte, and the smallest for the Merck compound, the least polar analyte. Copyright 1999 John Wiley & Sons, Ltd.     

Asymmetric catalytic synthesis of lysine by hydrogenation of α-nitrocaprolactam

Conclusions The enantioselective hydrogenation of-nitrocaprolactam (I) is effected on a chiral Pd complex, obtainedin situ in the presence of S--phenylethylamine, to give S--aminocaprolactam (II), hydrolysis of which gives S-lysine. The optical yield varies from 1 to 13% according to the solvent and concentration of chiral ligand. On a Pd complex with S-N-isopropyl--phenylethylamine, enantioselective hydrogenation of (I) gives an excess of the S-enantiomer of (II) (2%). On a Pd complex with S-phenylalaninol, hydrogenation of (I) leads to the R configuration of (II) with EE 7.2%.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1597–1600, July, 1987.     

Asymmetrical synthesis of lysine derivatives

Conclusions The stereoselective aminolysis of the azlactone of DL-diacetyllysine by the action of S--phenylethylamine in t-BuOH leads to an excess of the SS-diastereomer of the -phenylethylamine or diaceyllysine. Crystallization of the mixture of diastereomeric amides gave the optically pure S--phenylethylamide of S-diacetyllysine.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 925–927, April, 1986.     

Infrared and Raman spectroscopic investigations of δ2-oxazolin-5-ones

The infrared and Raman Spectra of saturated and unsaturated ²-oxazolin-5-ones (azlactones) have been studied for CCl₂, CHCl₃, i-PrOH, and t-BuOH solutions and for the solid phase. Frequency assignments have been made for C=O bond stretching in the region 1825–1770 cm^–1 and for a mixed C=C and C=N vibration at 1690–1550 cm^–1. All of the azlactones showed an intense, characteristic absorption in a narrow range near 900 cm^–1 which was assigned to a deformation vibration of the oxazolone ring.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1133–1136, August, 1989.     

Catalytic asymmetric synthesis of lysine α-phenylethylamide by diastereoselective hydrogenation

Conclusions The catalyzed asymmetric synthesis of R-lysine S--phenylethylamide has been carried out by the diastereoselective hydrogenation of 5-cyano-2-hydroxyiminovaleric acid S--phenylethylamide over a skeletal nickel catalyst in a solvent containing -phenylethylamine, at raised pressures. The excess of the RS-diastereoisomer was 6–12%.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 849–852, April, 1987.