Lipids ofBryonia alba

The lipid composition of the roots ofBryonia alba (Cucurbitaceae) have been studied: It consists of fractions of 3-acyloxy-24-alkyl(alkenyl)-cholest-7-enes (I), triacylglycerols (II), 1,2-diacyl-3-monoglycopyranosyl-sn-glycerols (III), 1,2-diacyl-3-diglycopyranosyl-sn-glycerols (IV), 1,3-bis(3-sn-phosphatidyl)glycerols (V), 3-sn-phosphatidylethanolamines (VI), 3-sn-phosphatidylcholines (VII), and methyl esters of fatty acids (VIII). The amount of unsaturated fatty acids in the lipid fractions (I–VIII) is 60–94%, the main component being linolenic acid.A. L. Mndzhoyan Institute of Fine Organic Chemistry of the Academy of Sciences of the Armenian SSR, Erevan. Translated from Khimiya Pridodnykh Soedinenii, Vol. 6, pp. 781–785, November–December, 1980.     

Parahydrogen‐Based Hyperpolarization for Biomedicine

Magnetic resonance (MR) is one of the most versatile and useful physical effects used for human imaging, chemical analysis, and the elucidation of molecular structures. However, its full potential is rarely used, because only a small fraction of the nuclear spin ensemble is polarized, that is, aligned with the applied static magnetic field. Hyperpolarization methods seek other means to increase the polarization and thus the MR signal. A unique source of pure spin order is the entangled singlet spin state of dihydrogen, parahydrogen (pH₂), which is inherently stable and long‐lived. When brought into contact with another molecule, this “spin order on demand” allows the MR signal to be enhanced by several orders of magnitude. Considerable progress has been made in the past decade in the area of pH₂‐based hyperpolarization techniques for biomedical applications. It is the goal of this Review to provide a selective overview of these developments, covering the areas of spin physics, catalysis, instrumentation, preparation of the contrast agents, and applications.     

Synthesis of fluorinated 2,6-heptanediones and 2-oxa-6- azabicyclo[2.2.2]octanes from 1,4-dihydropyridines

Electrophilic fluorination of Hantzsch-type 1,4-dihydropyridines with Selectfluor^® led to the formation of new fluorinated 2,6-heptanediones - dialkyl 2,4-diacetyl-2,4-difluoro-3-phenylpentanedioates. Novel 2,6-heptanedione derivatives in reaction with hydrazine hydrate easily form 6-amino-4,7-difluoro-3-hydroxy-1,3-dimethyl-5-oxo-8-phenyl-2-oxa-6-azabicyclo[2.2.2]octanes instead of the corresponding diazepine derivatives. The obtained 2-оxa-6-azabicyclo[2,2,2]octanes are thermally stable at the temperatures below 50°С. At higher temperatures rearrangement of 2-oxa-6-azabicyclo[2,2,2]octanes offers new fluorine-containing pyrazolinone derivatives - alkyl esters of 2-fluoro-2-((4-fluoro-3-methyl-5-oxo-4,5-dihydro-1H-pyrazol-4-yl)(phenyl)methyl)-3-oxobutanoates.     

Convenient one-pot formation of highly functionalized 5-bromo-2-aminothiazoles,potential endocannabinoid hydrolase MAGL inhibitors

Highly functionalized 5-bromo-2-amino-1,3-thiazoles bearing various substituents could be easily prepared by a rapid and efficient one-pot method, using simple starting materials and mild conditions while avoiding the use of metal catalysts or inconvenient reagents such as elemental halogens. These useful products can serve as starting materials for other reactions or as pharmacologically interesting compounds. In our work we have shown that the resulting 5-bromothiazole compounds could lead to monoacylglycerol lipase (MAGL) inhibition in the μM range.     

Bücherbesprechungen

Ohne Zusammenfassung     

Kritik der Grundlagen einer Theorie der Kolloide

Ohne Zusammenfassung(M. 164–178.)Anmerk. D. Red, Das Manuskript des vorliegenden Teiles ist gleichzeitig mit den zu anfang dieses Jahres veröffentlichten und gleichbetitelten theoretischen Untersuchungen des Verf. Eingelaufen. Eine längere Krankheit des Verf. Hat die Veröffentlichung dieses Teiles verzögert.Vgl. Diese Zeitschrift 2, 361; 3, 13; s. auch Fußnote 3 auf S. 362 (Bd. II).     

Über Condensation von Glyoxal mit Isobutyraldehyd

Ohne ZusammenfassungIndem wir zum Schlusse unserem hochverehrten Lehrer, Herrn Hofrath Ad. Lieben, für seine liebenswürdige Unterstützung unseren besten Dank ausdrücken, möchten wir uns sowohl die eingehendere Untersuchung der beschriebenen Condensationsproducte, als auch die Condensation von Glyoxal mit anderen Aldehyden als Arbeitsgebiet gewahrt wissen.     

Single-crystal studies of peptide prolyl and glycyl 15N shielding tensors

15N shielding tensors were determined for the central peptide groups in GGV, AGG, and APG by single-crystal NMR. We find that the angle between the downfield component (delta11) and the N-H or the N-C(delta) (pro) bonds is in the range of 20-23 degrees and in accord with previous solid-state NMR measurements. However, AGG, unlike APG or GGV, has a distorted peptide plane, and delta11 lies approximately in the plane of N, C(alpha), and H rather than in the peptide plane defined by heavy atoms. Accurate orientations of delta22 and delta33 were determined, and the usual assumption that delta22 is along the peptide normal was found only in APG which has a highly nonaxial tensor. More generally, delta22 and delta33 are rotated about the delta11 axis (36 degrees in GGV). These results are compared with DFT calculations to gain a structural understanding of the effects of intermolecular interactions on shielding tensor principal components and orientations. Trimeric clusters containing H-bonded neighbors predict the orientations of the principal components within 2-3 degrees, but calculated principal components are less quantitative. Possible reasons for this disagreement are explored.