Un nouvel agent de glycosylation: l'anhydride trifluorométhanesulfonique. Synthèse des α et β O-glycosyl-L-sérine, -L-thréonine et -L-hydroxyproline

1981 ◽  
Vol 59 (2) ◽  
pp. 473-481 ◽  
Author(s):  
J. M. Lacombe ◽  
A. A. Pavia ◽  
J. M. Rocheville
Keyword(s):  
Column Chromatography ◽  
Optical Rotation ◽  
Benzyl Ester ◽  
Experimental Procedure ◽  
Condensation Products ◽  
Benzyl Esters ◽  
Similar Yield ◽  
C Nmr

When 2,3,4,6-tetra-O-benzyl-D-glucopyranose, -D-galactopyranose and 2,3,4-tri-O-benzyl-D-xylopyranose were allowed to react in the cold in dichloromethane or acetonitrile as solvent in the presence of trifluoromethanesulfonic (triflic) anhydride, with methyl or benzyl esters of the N-(benzyloxycarbonyl)-L-serine, -L-threonine, and -L-hydroxyproline, an anomeric mixture of the corresponding O-glycosylaminoacids was obtained (55 to 90% overall yield), with the α-anomer being predominant. The same experimental procedure was successfully applied to the condensation of the benzyl ester of the N-(benzyloxycarbonyl)-L-hydroxyproline with 2,3,4-tri-O-benzyl-L-arabinopyranose and 2,3,5-tri-O-benzyl-L-arabinofuranose affording the corresponding condensation products with similar yield. Pure α and β anomers were obtained after column chromatography or crystallization with 30 to 65% yield. Hydrogenolysis of benzyl derivatives afforded the unprotected compounds. Optical rotation, 1H and 13C nmr were the main methods used to assess structure and stereochemistry.

Progesterone Side-Chain Cleavage by Aspergillus versicolor

2013 ◽  
Vol 781-784 ◽  
pp. 1164-1167
Author(s):  
Hai Ying Yang ◽  
Hai Ling Su ◽  
Gang Du ◽  
Guang Jian Shen ◽  
Jing Xian Sun ◽  
...  
Keyword(s):  
Melting Point ◽  
Column Chromatography ◽  
Optical Rotation ◽  
Side Chain ◽  
Spectroscopic Methods ◽  
Aspergillus Versicolor ◽  
Side Chain Cleavage ◽  
H Nmr ◽  
Chain Cleavage ◽  
C Nmr

Side chain cleavage of progesterone occurred in the biotransformation by Aspergillus versicolor. The conversion products were purified by column chromatography with ether/EtOAc and characterized by spectroscopic methods including 1H NMR, 13C NMR, IR, UV, MS and physical constants such as melting point and optical rotation. Those conversion products were identified as testosterone, androstenedione and androstenediendione.

An unusual reaction of a bridged triterpenoid α-diketone with acetic anhydride

1991 ◽  
Vol 56 (12) ◽  
pp. 2917-2935 ◽  
Author(s):  
Eva Klinotová ◽  
Václav Křeček ◽  
Jiří Klinot ◽  
Miloš Buděšínský ◽  
Jaroslav Podlaha ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Nmr Spectroscopy ◽  
Acetic Anhydride ◽  
Spectral Methods ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mild Conditions ◽  
Condensation Products ◽  
Unsaturated Lactones ◽  
C Nmr

3β-Acetoxy-21,22-dioxo-18α,19βH-ursan-28,20β-olide (IIIa) reacts with acetic anhydride in pyridine under very mild conditions affording β-lactone IVa and γ-lactones Va and VIIa as condensation products. On reaction with pyridine, lactones Va and VIIa undergo elimination of acetic acid to give unsaturated lactones VIIIa and IXa, respectively. Similarly, the condensation of 20β,28-epoxy-21,22-dioxo-18α,19βH-ursan-3β-yl acetate (IIIb) with acetic anhydride leads to β-lactone IVb and γ-lactone Vb; the latter on heating with pyridine affords unsaturated lactone VIIIb and 21-methylene-22-ketone Xb. The structure of the obtained compounds was derived using spectral methods, particularly 1H and 13C NMR spectroscopy; structure of lactone IVa was confirmed by X-ray diffraction.

Syntheses, Spectroscopy And Crystal Structures Of (R)-N-(1-Aryl-Ethyl)Salicylaldimines And [Rh{(R)-N-(1-Aryl-Ethyl)Salicylaldiminato}(η4-Cod)] Complexes

2007 ◽  
Vol 62 (6) ◽  
pp. 807-817 ◽  
Author(s):  
Mohammed Enamullah ◽  
A.K.M. Royhan Uddin ◽  
Anne-Christine Chamayou ◽  
Christoph Janiak
Keyword(s):  
Mass Spectrometry ◽  
Schiff Base ◽  
Schiff Bases ◽  
Structure Determination ◽  
Chelate Ring ◽  
Optical Rotation ◽  
X Ray ◽  
Mononuclear Complexes ◽  
Chiral Schiff Base ◽  
C Nmr

Condensation of salicylaldehyde with enantiopure (R)-(1-aryl-ethyl)amines yields the enantiopure Schiff bases (R)-N-(1-aryl-ethyl)salicylaldimine (HSB*; aryl = phenyl, 2-methoxyphenyl, 3- methoxyphenyl, 4-methoxyphenyl (4), 4-bromophenyl (5), 2-naphthyl). These Schiff bases readily react with dinuclear (acetato)(η4-cycloocta-1,5-diene)rhodium(I), [Rh(μ-O2CMe)(η4-cod)]2, to afford the mononuclear complexes, cyclooctadiene-((R)-N-(1-aryl-ethyl)salicylaldiminato-κ2N,O)- rhodium(I), [Rh(SB∗)(η4-cod)] (SB* = deprotonated chiral Schiff base = salicylaldiminate; aryl = phenyl (7), 2-methoxyphenyl, 4-methoxyphenyl, 4-bromophenyl, 2-naphthyl). The complexes have been characterized by IR, UV/vis, 1H/13C NMR and mass spectrometry, optical rotation as well as by single-crystal X-ray structure determination for 4, 5 and 7. The structure of 5 shows C-Br· · ·π contacts. Compound 7 is only the second example of a Rh(η4-cod) complex with a six-membered Rh-N,O-chelate ring

Comparative effects of L-NNA and alkyl esters of L-NNA on pulmonary vasodilator responses to ACh, BK, and SP

1994 ◽  
Vol 266 (6) ◽  
pp. H2416-H2422 ◽  
Author(s):  
D. Y. Cheng ◽  
B. J. DeWitt ◽  
T. J. McMahon ◽  
P. J. Kadowitz
Keyword(s):  
Substance P ◽  
Vagal Stimulation ◽  
Benzyl Ester ◽  
No Synthase ◽  
Flow Conditions ◽  
Inhibitory Effects ◽  
Vascular Bed ◽  
Pulmonary Vasodilator ◽  
Benzyl Esters ◽  
Pulmonary Vascular Bed

The comparative effects of the nitric oxide (NO) synthase inhibitors N omega-nitro-L-arginine (L-NNA), N omega-nitro-L-arginine methyl ester (L-NAME), and N omega-nitro-L-arginine benzyl ester (L-NABE) on baseline tone and on vasodilator responses to acetylcholine (ACh), bradykinin (BK), and substance P (SP) were compared in the pulmonary vascular bed of the cat under constant flow conditions. After administration of the NO synthase inhibitors in intravenous doses of 100 mg/kg, the increase in lobar arterial pressure and the attenuation of vasodilator responses to ACh, BK, and SP were similar, whereas responses to adenosine and felodipine, endothelium-independent vasodilator agents, were not altered. In addition to inhibiting responses to ACh, BK, and substance P, the NO synthase inhibitors enhanced vasodilator responses to S-nitroso-N-acetylpenicillamine and NO. Moreover, atropine inhibited pulmonary vasodilator responses to ACh but not to SP or BK, and L-NAME or L-NABE had no effect on the decrease in heart rate in response to efferent vagal stimulation, a muscarinic receptor-mediated response that is independent of NO release. The similar inhibitory effects of L-NNA, L-NAME, and L-NABE on vasodilator responses to ACh, BK, and SP suggest that the L-arginine analogue, L-NNA, as well as the methyl and benzyl esters of L-NNA are useful probes for studying NO-mediated endothelium-dependent responses in the pulmonary vascular bed of the intact-chest cat.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardenolide aus Ornithogalum nutans (2 n = 28), 1. Mitteilung / Cardenolides from Ornithogalum nutans (2 n = 28), Part

1992 ◽  
Vol 47 (10) ◽  
pp. 1444-1458 ◽  
Author(s):  
Roland Ferth ◽  
Andreas Baumann ◽  
Wolfgang Robien ◽  
Brigitte Kopp
Keyword(s):  
Acid Hydrolysis ◽  
Column Chromatography ◽  
Structure Elucidation ◽  
European Species ◽  
H Nmr ◽  
First Time ◽  
Hydrolysis Of ◽  
C Nmr

From leaves and bulbs of Ornithogalum nutans L. (2 n = 28), seventeen cardenolides were isolated by column chromatography, DCCC and TLC. The structure elucidation was performed by means of 1H NMR, 13C NMR, HH-Cosy, HC-Cosy and FAB-MS studies and identification of the sugar moieties by GLC after acid hydrolysis of the cardenolides. Sugar compounds were identified as digitoxose, 3-acetyl-digitoxose, 2-deoxy-allose, 6-deoxy-allose, rhamnose, xylose and apiose. Glycosides of 7β,15β, 16 α-trihydroxy-uzarigenin, 8β,16 α-dihy-droxy, 15-oxo-uzarigenin, 3 β, 11β-dihydroxy, 12-oxo, 18-nor-5 α-card-13-enolid, 11 α-hydroxygitoxigenin, 12-oxo,8, 14β-epoxy-uzarigenin, 8β-hydroxy, 15-oxo-uzarigenin and 12β-hydroxy-oleandrigenin are described for the first time, the presence of oleandrigenin-glycosides in the genus Ornithogalum was not known until now. Ornithogalum nutans L. shows a different cardenolide pattern from the second European species of the section Myogalum (LINK) PETERM. - Ornithogalum boucheanum (KUNTH) ASCHERS.

Neue Untersuchung über Inhaltsstoffe aus Aloe-und Rhamnus-Arten, XV [1] Homonataloin A und B aus Aloe lateritia: Reindarstellung, Konstitutions-und Konfigurationsaufklärung der Diastereomeren / A New Investigation on Constituents of Aloe and Rhamnus Species, XV [1] Hom onataloins A and B from Aloe lateritia: Isolation, Structure and Configurational Determ ination of the Diastereomers

1991 ◽  
Vol 46 (3-4) ◽  
pp. 177-182 ◽  
Author(s):  
Hans-W. Rauwald ◽  
Deo-D. Niyonzima
Keyword(s):  
Chemical Shifts ◽  
Optical Rotation ◽  
Coupling Constants ◽  
Cd Spectra ◽  
Large Coupling ◽  
H Nmr ◽  
Leaf Exudate ◽  
Hydroxyl Protons ◽  
Nmr Signals ◽  
C Nmr

From the leaf exudate of Aloe lateritia ENGLER the C-glucosyl com pounds homonataloin, aloeresin A and aloesin (synon. aloeresin B) were isolated together with the anthraquinone nataloeem odin-8-methylether and spectroscopically identified. Hom onataloin, widely distributed in Aloe species, was separated into homonataloin A and B by combined TLC and DCCC. In their 1 D and 2D 1H NMR spectra only the shifts of the 2′-hydroxyl protons of both glucosyl residues differ significantly, indicative of 10 S (A) resp. 10 S (B) configurations. In both com pounds the anthrone is in β-position of the D-glucopyranosyl, as determined by the large coupling constants of the anomeric protons. The 13C NMR signals are unambiguously assigned by the use of DEPT, APT and gated-decoupling methods. Only the chemical shifts of C -11 and C -14 show significant differences between both diastereomers due to the adjacent 2′-sugar hydroxyls. The two homonataloins differ mostly in optical rotation and circulardichroism due to different configurations at C - 10 of the anthrone part. The absolute configurations of the diastereomers are determined by correlation of their CD spectra with the CD spectra of the structural analogues 7-hydroxyaloins A and B, which shows that hom onataloin A is the 10 S, 1′S-compound and that homonataloin B has 10 R, 1′S-configuration.

scholarly journals Design, Synthesis and Biological Evaluation of Pentacyclic Triterpene Derivatives: Optimization of Anti-ABL Kinase Activity

Molecules ◽  
2019 ◽  
Vol 24 (19) ◽  
pp. 3535 ◽  
Author(s):  
Halil I. Ciftci ◽  
Mohamed O. Radwan ◽  
Safiye E. Ozturk ◽  
N. Gokce Ulusoy ◽  
Ece Sozer ◽  
...  
Keyword(s):  
Kinase Inhibitor ◽  
K562 Cells ◽  
Biological Evaluation ◽  
Benzyl Ester ◽  
Myelogenous Leukemia ◽  
Pentacyclic Triterpene ◽  
Abl Kinase ◽  
Molecular Targeted Drug ◽  
Benzyl Esters

Imatinib, an Abelson (ABL) tyrosine kinase inhibitor, is a lead molecular-targeted drug against chronic myelogenous leukemia (CML). To overcome its resistance and adverse effects, new inhibitors of ABL kinase are needed. Our previous study showed that the benzyl ester of gypsogenin (1c), a pentacyclic triterpene, has anti-ABL kinase and a subsequent anti-CML activity. To optimize its activities, benzyl esters of carefully selected triterpenes (PT1–PT6), from different classes comprising oleanane, ursane and lupane, and new substituted benzyl esters of gypsogenin (GP1–GP5) were synthesized. All of the synthesized compounds were purified and charachterized by different spectroscopic methods. Cytotoxicity of the parent triterpenes and the synthesized compounds against CML cell line K562 was examined; revealing three promising compounds PT5, GP2 and GP5 (IC50 5.46, 4.78 and 3.19 μM, respectively). These compounds were shown to inhibit extracellular signal-regulated kinase (ERK) downstream signaling, and induce apoptosis in K562 cells. Among them, PT5 was identified to have in vitro activity (IC50 = 1.44 μM) against ABL1 kinase, about sixfold of 1c, which was justified by molecular docking. The in vitro activities of GP2 and GP5 are less than PT5, hence they were supposed to possess other more mechanisms of cytotoxicity. In general, our design and derivatizations resulted in enhancing the activity against ABL1 kinase and CML cells.

Application of Benzyl Ester of Modified Vegetable Oils as Rubber Processing Oils

2011 ◽  
Vol 415-417 ◽  
pp. 1164-1167 ◽  
Author(s):  
Hasleena Boontawee ◽  
Charoen Nakason ◽  
Azizon Kaesaman ◽  
Anoma Thitithammawong ◽  
Sopa Chewchanwuttiwong
Keyword(s):  
Fatty Acids ◽  
Vegetable Oils ◽  
Dynamic Mechanical Properties ◽  
Benzyl Ester ◽  
Molar Ratio ◽  
Mixing Energy ◽  
Rubber Compounds ◽  
Different Types ◽  
Benzyl Esters ◽  
Hydrolysis Of

Benzyl esters of fatty acids based on three types of vegetable oils (i.e., coconut, palm, and soybean oils) were in-house prepared. They were used as alternative rubber processing oil to replace conventional aromatic oil which has been banned by European community since December 2009. Fatty acids were first prepared by hydrolysis of vegetable oils and thereafter esterified with benzyl alcohol in the presence of sulfuric acid as a catalyst. The reaction based on molar ratio of fatty acid:benzyl alcohol:sulfuric acid was set at 1.5:1.0:0.05 gave yield of benzyl esters higher than 80%. Rubber compounds containing different types of benzyl ester were prepared according to the standard formulation of ASTM 3184. It was found that the processing oil in the form of benzyl esters is possible to use instead of aromatic oil in rubber formulation. Various parameters and properties include mixing energy, Mooney viscosity, curing, mechanical and dynamic mechanical properties of rubber compounds and vulcanizates have been investigated.

scholarly journals E64 [trans-epoxysuccinyl-l-leucylamido-(4-guanidino)butane] analogues as inhibitors of cysteine proteinases: investigation of S2 subsite interactions

1994 ◽  
Vol 299 (2) ◽  
pp. 389-392 ◽  
Author(s):  
B J Gour-Salin ◽  
P Lachance ◽  
M C Magny ◽  
C Plouffe ◽  
R Ménard ◽  
...  
Keyword(s):  
Amino Acid ◽  
Cathepsin B ◽  
Benzyl Ester ◽  
Amide Proton ◽  
Side Chain ◽  
Cysteine Proteinases ◽  
Enzyme Substrate ◽  
Amide Derivatives ◽  
Benzyl Esters ◽  
S2 Subsite

A number of epoxysuccinyl amino acid benzyl esters (HO-Eps-AA-OBzl) and benzyl amides (HO-Eps-AA-NHBzl) (where AA represents amino acid) were synthesized as analogues of E64, a naturally occurring inhibitor of cysteine proteinases. These inhibitors were designed to evaluate if selectivity for cathepsin B could be achieved by varying the amino acid on the basis of known substrate specificity. Contrary to the situation with substrates, it was found that variation of the amino acid in the E64 analogues does not lead to major changes in the kinetic parameter kinac./Ki and that the specificity of these analogues does not parallel that observed for substrates. This is particularly true in the case of the benzyl ester derivatives where the deviation from substrate-like behaviour is more important than with the benzyl amide derivatives. The results suggest that the amide proton of the benzyl amide group in HO-Eps-AA-NHBzl interacts in the S2 subsite in both cathepsin B and papain and contributes to increase the potency of these inhibitors. The kinetic data also suggest that differences in the orientation of the C alpha-C beta bond of the side chain in the S2 subsite of the enzyme might explain the differences between substrate and E64 analogue specificities. This hypothesis is supported by the fact that the order of inactivation rates with chloromethane inhibitors (which are believed to be good models of enzyme-substrate interactions) is indeed very similar to that observed with the corresponding amidomethylcoumarin substrates. In conclusion, the information available from S2-P2 interactions with substrates cannot be used to enhance the selectivity of the E64 analogues in a rational manner.

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