Selective Protection Strategies in the Synthesis of TRIS-Fatty Ester Derivatives

2002 ◽  
Vol 55 (10) ◽  
pp. 629 ◽  
Author(s):  
R. Adhikari ◽  
C. L. Francis ◽  
G. W. Simpson ◽  
Q. Yang
Keyword(s):  
Fatty Ester ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Selective Protection ◽  
Palmitoyl Chloride ◽  
Protection Strategies ◽  
Mild Hydrolysis ◽  
Derivatives Of ◽  
Trimethyl Orthoformate ◽  
Acyl Derivatives

A methodology for the selective synthesis of lipophilic acyl derivatives of the glycinamido triol (1) with either one, two, or three fatty ester groups has been established. Peracylation of (1), with palmitoyl chloride gave the triacylated derivative. Conversion of (1) into the acetonide, followed by acylation with either palmitoyl chloride or lauroyl chloride, and acetal hydrolysis provided the monoacylated derivatives. Treatment of (1) with trimethyl orthoacetate gave the orthoacetate derivative. Mild hydrolysis provided the monoacetate/diol. Acylation of the two hydroxyl groups with palmitoyl chloride gave the dipalmitate/acetate. Selective cleavage of the acetate group afforded the dipalmitate of (1). Analogous chemistry with trimethyl orthoformate provided the same dipalmitate via the orthoformate, monoformate/diol, and dipalmitate/formate. A more robust synthesis of the dipalmitate was achieved by converting the hydroxyl group of the acetonide of (1) into a tert-butyldiphenylsilyl ether, followed by acetal hydrolysis, palmitoylation of the liberated hydroxyl groups, and desilylation.

scholarly journals SYNTHESIS OF 1,2;3,4-DI-O-ISOPROPYLIDENE-6- O-[4-(1H-AZOL-1-YLMETHYL) PHENYL]- ¯-D-GALACTOPYRANOSE AND 1,2,3,4-TETRA-O-ACETYL-6- O-[4-(1H-AZOL-1- YLMETHYL)PHENYL]-¯-D-GLUCOPYRANOSE

2017 ◽  
Vol 17 (5) ◽  
pp. 122-128
Author(s):  
Z.P. Belousova ◽  
P.P. Purygin ◽  
A.P. Tyurin
Keyword(s):  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Secondary Hydroxyl ◽  
Primary Hydroxyl ◽  
Derivatives Of

Derivatives of D-galactose and D-glucose substituted for the primary hydroxyl group, which contain an aglycone azolylmethylphenyl fragments (for imidazole, 1,2,4-triazole, benzimidazole and benzotriazole) has been synthesized. Toprotect the secondary hydroxyl groups of monosaccharides acetyl and isopropylidene groups were used.

scholarly journals Antioxidant activity of some coumarins / Antioxidačná activita niektorých kumarínov

2015 ◽  
Vol 62 (s9) ◽  
pp. 41-45 ◽  
Author(s):  
F. Šeršeň ◽  
M. Lácová
Keyword(s):  
Antioxidant Activity ◽  
Acetic Acid ◽  
Superoxide Anion ◽  
The Other ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Coumarin Derivatives ◽  
Antioxidant Effectiveness ◽  
Derivatives Of ◽  
Superoxide Anion Radicals

AbstractNineteen derivatives of coumarin were tested on the scavenging of 2,2-diphenyl-1-picrylhydrazyl, hydroxyl and superoxide anion radicals. It was found that antioxidant activity exhibits only such coumarins that contain hydroxyl groups. The derivatives without hydroxyl group showed very low antioxidant effectiveness or they were ineffective. On the other hand, the greatest antioxidant effectiveness was exhibited by coumarin derivatives that contained hydroxyl groups in 6 or 8 position, whereas the effectiveness of derivatives with one hydroxyl group in 4, 5 or 7 position was very low. Based on scavenging of the above-mentioned radicals, it was found that the most effective scavengers were 7,8-dihydroxy-4-methylcoumarin (i.e. compound that contains two hydroxyl groups in 7 and 8 positions), (7,8-dihydroxy-2-oxo-2H-chromen-4-yl)acetic acid (this compound contains in addition to two hydroxyl groups in 7 and 8 positions also one hydroxyl group in the acidic residue), esculetin (6,7-dihydroxycoumarin) and 6,7-dihydroxy-4-methylcoumarin.

scholarly journals New bio-amphiphilic structures of sucrose via amides linkages

2019 ◽  
Vol 10 (4) ◽  
pp. 3143-3154
Author(s):  
Salih Mahdi Salman
Keyword(s):  
Chemical Structure ◽  
13C Nmr Spectroscopy ◽  
Alkyl Halides ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Staudinger Reaction ◽  
Target Structure ◽  
Leaving Group ◽  
Derivatives Of ◽  
Resolution Mass

A series of four new derivatives of sucrose have been synthesized using the straightforward methodology in order to give a mono substituted analogs of sucrose at C-6’ of fructose moiety. The synthesis was started from the reaction of sucrose with tert-butylchlorodiphenylsilane, which is able to react with an only less steric hindrance hydroxyl group at C-6’ due to its bulky structure. The other hydroxyl groups were acetylated by the reaction with acetic anhydride in pyridine. Then free the hydroxyl group at C-6’ again by the treatment with t-butylammonium fluoride in THF. The later was activated by conversion to a good leaving group via tosylation, followed by functionalized via azidation to give the precursor of the target series hepta-O-acetyl-6’-azido- sucrose. The precursor was coupled with four alkyl halides (C12, C8-4, C14, C10-8) via Staudinger reaction to produced the target structure after deacetylating. The purity and chemical structure of the synthesized compound was confirmed by CHN elemental analysis, high-resolution mass and 1H, 13C NMR spectroscopy. 

Glucuronidierung von Hydroxy-testosteron- und Hydroxy-androstendion-Verbindungen durch die mikrosomale UDP-Glucuronyl-Transferase der Rattenleber / Glucuronidation of Hydroxy-compounds of Testosterone and Androstenedione by the Microsomal UDP Glucuronyl Transferase of Rat Liver

1972 ◽  
Vol 27 (1) ◽  
pp. 49-52
Author(s):  
Herbert Schriefers ◽  
Rüdiger Ghraf ◽  
Birgit Lehnen
Keyword(s):  
High Specificity ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Testosterone Metabolism ◽  
Glucuronyl Transferase ◽  
Hydroxy Compounds ◽  
Derivatives Of ◽  
Special Case ◽  
Free Steroid ◽  
Very High

The microsomal UDP glucuronyl transferase exhibits activities against hydroxy derivatives of androstenedione (hydroxyl groups in the positions 2β, 6β or 16α) between 5% and 27% of the extent shown against testosterone. 2β-, 6β· and 16α-hydroxyl groups are much less efficient in accepting the glucuronic acid than the 17β-hydroxyl group.However, the acceptor function of the 17β-hydroxyl group is restricted by other hydroxy substituents in the testosterone molecule to an increasing extent represented by the following sequence: 2α, 6β, 6α, 16α, and 7α. A special case is represented by 2β-hydroxy-testosterone. The transferase displays a higher activity against this compound than against testosterone.Apparently the transferase approaches the steroid molecule from the α-side (with the β-side there is also contact at the C-6 atom) requires the 17β-hydroxyl group and the 3-oxo-4-ene system to display full activity.Thus the very high specificity of the transferase for testosterone explains the selective action of this enzyme on testosterone metabolism in the liver. This action is expressed by the fact, that in liver perfusates the percentage of testosterone in the glucuronide fraction is twice as large as the percentage of testosterone in the free steroid fraction.

scholarly journals Identification of Novel Gymnodimines and Spirolides from the Marine Dinoflagellate Alexandrium ostenfeldii

Marine Drugs ◽  
2018 ◽  
Vol 16 (11) ◽  
pp. 446 ◽  
Author(s):  
Christian Zurhelle ◽  
Joyce Nieva ◽  
Urban Tillmann ◽  
Tilmann Harder ◽  
Bernd Krock ◽  
...  
Keyword(s):  
Chemical Diversity ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Alexandrium Ostenfeldii ◽  
Exocyclic Methylene ◽  
Polyketide Chain ◽  
Marine Dinoflagellates ◽  
Toxin Class ◽  
Derivatives Of

Cyclic imine toxins are neurotoxic, macrocyclic compounds produced by marine dinoflagellates. Mass spectrometric screenings of extracts from natural plankton assemblages revealed a high chemical diversity among this toxin class, yet only few toxins are structurally known. Here we report the structural characterization of four novel cyclic-imine toxins (two gymnodimines (GYMs) and two spirolides (SPXs)) from cultures of Alexandrium ostenfeldii. A GYM with m/z 510 (1) was identified as 16-desmethylGYM D. A GYM with m/z 526 was identified as the hydroxylated degradation product of (1) with an exocyclic methylene at C-17 and an allylic hydroxyl group at C-18. This compound was named GYM E (2). We further identified a SPX with m/z 694 as 20-hydroxy-13,19-didesmethylSPX C (10) and a SPX with m/z 696 as 20-hydroxy-13,19-didesmethylSPX D (11). This is the first report of GYMs without a methyl group at ring D and SPXs with hydroxyl groups at position C-20. These compounds can be conceived as derivatives of the same nascent polyketide chain, supporting the hypothesis that GYMs and SPXs are produced through common biosynthetic genes. Both novel GYMs 1 and 2 were detected in significant amounts in extracts from natural plankton assemblages (1: 447 pg; 2: 1250 pg; 11: 40 pg per mL filtered seawater respectively).

Cyclitols. XXV. Benzyl ethers of ( - )-inositol. Lack of selectivity in O-substitution

1966 ◽  
Vol 19 (9) ◽  
pp. 1683 ◽  
Author(s):  
SJ Angyal ◽  
TS Stewart
Keyword(s):  
Benzyl Chloride ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Benzyl Ethers ◽  
Marked Preference ◽  
Derivatives Of

Several partially benzylated derivatives of (-)-inositol have been synthesized. None of the reactions tried showed marked preference towards equatorial hydroxyl groups but in one instance-benzylation in benzyl chloride as solvent-an axial hydroxyl group reacted preferentially.

scholarly journals The study of the reactivity of derivatives of hydroxycinnamic alcohol as model compounds of lignin

2020 ◽  
Vol 61 (1) ◽  
pp. 33-39
Author(s):  
Oleg K. Karimov ◽  
◽  
Galina Yu. Kolchina ◽  
Eldar M. Movsumzade ◽  
◽  
...  
Keyword(s):  
Aromatic Ring ◽  
Density Functional ◽  
Nucleophilic Attack ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Model Compounds ◽  
Hartree Fock ◽  
A Charge ◽  
Derivatives Of ◽  
Hybrid Density Functional

In the framework of method of the B3LYP hybrid density functional and the restricted Hartree-Fock method in the basis of 6-311 (d, p), quantum-chemical calculations of model compounds of lignin, i.e. derivatives of p-hydroxycinnamic alcohol were carried out. The structures and reactivity of coumaric, coniferyl and synapol alcohols were studied. The structural units of lignin contain hydroxyl groups which can be in the plane of benzene ring but can be turned up to 90° with respect to this plane. In the case of methoxy groups which are also present in coniferol and synapol alcohols, the methyl group is turned to 90° with respect to the plane of ring, as the most favorable conformation. Moreover, these compounds contain π,π-conjugations of the aromatic ring with an aliphatic fragment of molecule that affects the geometric characteristics of the molecule. For coumaric and coniferyl alcohols, the Сар–Сα bond length is 1.47 Ǻ. A slight deformation of valence angles for coumaric and synapol alcohols equal to 118.94° and 117.72° respectively instead of 120° at sp2 hybridization indicates the availability of conjugation. The use of a charge as a descriptor of attack selectivity of nucleophilic and electrophilic particles allows us to analized of the reactivity of these acids are given. It is found that the electronic structure of lignin is determined primarily by the charge distribution in its structural phenylpropane unit. In the molecules of all model compounds of lignin, the center for nucleophilic attack is the carbon of aromatic ring (E-ring) with a hydroxyl group, and in the molecule of synapol alcohol, this center is also the carbon of the aromatic ring (E-ring) with a methoxy group. In all three compounds, a center with an increased electron density appears on the Сβ carbon atom.

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