Partial hydrolysis of acyl 1,6-anhydro-β-D-glucopyranose

1984 ◽  
Vol 49 (8) ◽  
pp. 1780-1787 ◽  
Author(s):  
Štefan Kučár ◽  
Juraj Zámocký ◽  
Juraj Zemek ◽  
Dušan Anderle ◽  
Mária Matulová
Keyword(s):  
Acid Hydrolysis ◽  
Hydrazine Hydrate ◽  
Hydrogen Chloride ◽  
Ester Group ◽  
The Other ◽  
Hydroxyl Group ◽  
Partial Hydrolysis ◽  
Substantial Influence ◽  
Hydrolysis Of ◽  
Derivatives Of

Partial hydrolysis of per-O-acetyl- and per-O-benzoyl derivatives of 1,6-anhydro-β-D-glucopyranose with methanolic hydrogen chloride and hydrazine hydrate was investigated. The acyl group at C(3) is of substantial influence on the course of hydrolysis. The esterified hydroxyl group at C(3) was found to be most stable on acid hydrolysis with methanolic hydrogen chloride when compared with that at C(2), or C(4); on the other hand, this ester group is the most labile upon hydrolysis with hydrazine hydrate. Selectivity of the respective ester groups towards hydrolysis made it possible to prepare all variations of acetyl and benzoyl derivatives of 1,6-anhydro-β-D-glucopyranose.

Synthesis of 3-(5-Alkyl-4-acetyl(ethoxycarbonyl))-2-propenoates from Derivatives of 3-Phenoxy-2-furylmethylene

1992 ◽  
Vol 57 (8) ◽  
pp. 1684-1692 ◽  
Author(s):  
Štefan Marchalín ◽  
Vladimír Mlynárik ◽  
Anna Staňová ◽  
Dušan Ilavský
Keyword(s):  
Acid Hydrolysis ◽  
Hydrogen Chloride ◽  
Pure Form ◽  
Geometric Isomers ◽  
Transition Mechanism ◽  
One Step ◽  
Hydrolysis Of ◽  
Derivatives Of ◽  
Trisubstituted Furans

3-(2-Furyl)propenoates IV-VIII were obtained by treatment of 5-phenoxy-2-furylmethylene derivatives I-III with alcoholic hydrogen chloride in one step. The probable transition mechanism of synthons I-III into the 2,4,5-trisubstituted furans is presented. The geometric isomers E-IV, Z-V and Z-VI, isolated in pure form, were transformed into the corresponding acids E-IX, Z-IX and E-X by base-catalyzed hydrolysis. Acid hydrolysis of the 1,3-diketone I afforded (4Z,6Z)-6-acetyl-7-hydroxy-2,4,6-octatrien-4-olide (XI). Structure of the products was verified by spectral (IR, UV, NMR and mass) methods.

scholarly journals Stereoselective syntheses of 3-aminocyclooctanetriols and halocyclooctanetriols

2020 ◽  
Author(s):  
Emine Salamci ◽  
Yunus Zozik
Keyword(s):  
The Other ◽  
Hydroxyl Group ◽  
Efficient Synthesis ◽  
Azide Group ◽  
Methanol Treatment ◽  
Stereoselective Syntheses ◽  
Hydrolysis Of ◽  
Derivatives Of

The efficient synthesis of two new stereoisomeric 3-aminocyclooctanetriols and new halocyclitol derivatives of them starting from cis,cis-1,3-cyclooctadiene are reported. Reduction of cyclooctene endoperoxide, obtained by photooxygenation of cis,cis-1,3-cyclooctadiene, with zinc yielded a cyclooctene diol followed by acetylation of the hydroxyl group, which gave dioldiacetate by OsO4/NMO oxidation. The cyclooctane dioldiacetate prepared was converted to the corresponding cyclic sulphate via the formation of a cyclic sulphite in the presence of catalytic RuO4. Reaction of this cyclic sulphate with a nucleophilic azide followed by the reduction of the azide group provided the target, 3-aminocyclooctanetriol. The second key compound, bromotriol, was prepared by epoxidation of the cyclooctene diol with m-chloroperbenzoic acid followed by hydrolysis with HBr(g) in methanol. Treatment of bromotriol with NaN3 and the reduction of the azide group yielded the other 3-aminocyclooctanetriol desired. Hydrolysis of the epoxides with HCl(g) in methanol gave stereospecifically new chlorocyclooctanetriols.

Selective acid hydrolysis of 2,4,6-trimethylbenzyl esters and its application in peptide synthesis

1966 ◽  
Vol 19 (8) ◽  
pp. 1511 ◽  
Author(s):  
FHC Stewart
Keyword(s):  
Acid Hydrolysis ◽  
Peptide Synthesis ◽  
Trifluoroacetic Acid ◽  
Ester Group ◽  
Protecting Groups ◽  
Alkaline Conditions ◽  
Hydrolysis Of

Experiments with various N-acylamino acid 2,4,6-trimethylbenzyl esters have shown that the ester group is cleaved selectively by cold trifluoroacetic acid without affecting benzyloxycarbonyl, formyl, or phthaloyl amino-protecting groups present. The possible value of this selective behaviour in peptide syntheses where the use of alkaline conditions would be detrimental is illustrated by the synthesis of certain dipeptide derivatives.

THE ALDOBIOURONIC ACIDS OF HEMICELLULOSE B OF OAT HULLS

1956 ◽  
Vol 34 (3) ◽  
pp. 338-344 ◽  
Author(s):  
E. L. Falconer ◽  
G. A. Adams
Keyword(s):  
Glucuronic Acid ◽  
The Other ◽  
Partial Hydrolysis ◽  
Oat Hulls ◽  
Hydrolysis Of

Partial hydrolysis of hemicellulose B from oat hulls yielded two aldobiouronic acids, which were identified as 2-O-(4-O-methyl-α-D-glucopyruronosyl)-D-xylose and 2-O-(α-D-glucopyruronosyl)-D-xylose respectively. In addition, two aldotriouronic acids were isolated, one yielding on hydrolysis xylose and 4-O-methyl-glucuronic acid, and the other, xylose, galactose, and glucurone.

scholarly journals Potential Anti-Acetylcholinesterase Activity of Cassia timorensis DC.

Molecules ◽  
2020 ◽  
Vol 25 (19) ◽  
pp. 4545
Author(s):  
Nurul Amira Nurul Azman ◽  
Maram B. Alhawarri ◽  
Mira Syahfriena Amir Rawa ◽  
Roza Dianita ◽  
Amirah Mohd Gazzali ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Acetylcholinesterase Activity ◽  
The Other ◽  
Hydroxyl Group ◽  
Anionic Site ◽  
Methanol Extracts ◽  
Plant Parts ◽  
Ache Inhibitory Activity ◽  
First Time ◽  
Hydrolysis Of

Seventeen methanol extracts from different plant parts of five different Cassia species, including C. timorensis, C. grandis, C. fistula, C. spectabilis, and C. alata were screened against acetylcholinesterase (AChE). C. timorensis extracts were found to exhibit the highest inhibition towards AChE whereby the leaf, stem, and flower methanol extracts showed 94–97% inhibition. As far as we are aware, C. timorensis is one of the least explored Cassia spp. for bioactivity. Further fractionation led to the identification of six compounds, isolated for the first time from C. timorensis: 3-methoxyquercetin (1), benzenepropanoic acid (2), 9,12,15-octadecatrienoic acid (3), β-sitosterol (4), stigmasterol (5), and 1-octadecanol (6). Compound 1 showed moderate inhibition towards AChE (IC50: 83.71 μM), while the other compounds exhibited poor to slightly moderate AChE inhibitory activity. Molecular docking revealed that the methoxy substitution of 1 formed a hydrogen bond with TYR121 at the peripheral anionic site (PAS) and the hydroxyl group at C5 formed a covalent hydrogen bond with ASP72. Additionally, the OH group at the C3′ position formed an interaction with the protein at the acyl pocket (PHE288). This possibly explains the activity of 1 in blocking the entry of acetylcholine (ACh, the neurotransmitter), thus impeding the hydrolysis of ACh.

A synthesis of abequose (3,6-Dideoxy-D-xylo-hexose)

1977 ◽  
Vol 30 (6) ◽  
pp. 1269 ◽  
Author(s):  
C Copeland ◽  
RV Stick
Keyword(s):  
Acid Hydrolysis ◽  
Partial Hydrolysis ◽  
Hydrolysis Of

The S-methyl 3-O-dithiocarbonates of 1,2:5,6-di-O-isopropylidene-α-D-galactofuranose and ?gulofuranose have been prepared and subsequently reduced with tributylstannane to 3-deoxy-1,2:5,6-di-O-isopropylidene-μ- D-xylo-hexofuranose. Partial hydrolysis of this compound led to the 5,6-diolwhich was deoxygenated at C 6 to form 3,6-dideoxy-1,2-O- isopropylidene-α-D-xylo-hexofuranose, and subsequently abequose on acid hydrolysis. A rationale has been proposed for the variations in hydrolysis of di-O-isopropylidene-α-D-hexofuranoses and derivatives to their 5,6-diols.

O-Benzylidene Derivatives of D-Arabinose Diethyl and Dipropyl Dithioacetal

1996 ◽  
Vol 49 (3) ◽  
pp. 273 ◽  
Author(s):  
J Kuszmann ◽  
E Gacsbaitz
Keyword(s):  
Hydrochloric Acid ◽  
Zinc Chloride ◽  
Partial Hydrolysis ◽  
Kinetic Control ◽  
Toluenesulfonic Acid ◽  
Thermodynamic Phase ◽  
Hydrolysis Of ◽  
Derivatives Of

Benzylidenation of D-arabinose diethyl and dipropyl dithioacetals with α,α-dimethoxytoluene in the presence of p-toluenesulfonic acid has been studied in detail. Under kinetic control the two terminal dioxolan -type 4,5-O-(R)- and 4,5-O-(S)-benzylidene diastereomers are formed first which are in equilibrium with each other In the thermodynamic phase of the reaction the corresponding dioxan -type 3,5-O-(R)- benzylidene isomer is formed too, but all three monobenzylidene isomers are gradually converted into the four possible dioxolan -type 2,3 : 4,5-di-O benzylidene diastereomers . The dioxan -type 2,4:3,5-di-O-benzylidene isomer was present only in trace amounts. When benzaldehyde was used as reagent in the presence of hydrochloric acid or zinc chloride only the 2,3: 4,5-di-O-benzylidene diastereomers were formed. Partial hydrolysis of the dibenzylidene derivatives yielded the corresponding 2,3-O-benzylidene diastereomers. Structures, including the chirality of the benzylidene groups, were determined by n.m.r. spectroscopy. A mechanism suggested for the reaction was partially supported by equilibration studies.

Arylhydrazonothiazolidinones: Ring Cleavage and Alkylation of the 5-Arylhydrazono Derivatives of Rhodanine and Isorhodanine

1979 ◽  
Vol 34 (3) ◽  
pp. 507-510 ◽  
Author(s):  
Nazmi A. Kassab ◽  
Sanaa O. Abd Allah ◽  
Said A. Elbahaii
Keyword(s):  
Hydrazine Hydrate ◽  
The Other ◽  
Ring Cleavage ◽  
Ethyl Bromoacetate ◽  
Other Hand ◽  
Alkyl Derivatives ◽  
Derivatives Of

Abstract The 5-arylhydrazono derivatives of rhodanine and isorhodanine were subjected to the action of hydrazine hydrate to afford the arylhydrazonomercaptomethyl-triazolinones (3) and -triazolinthiones (3) respectively. Treatment of 1 with benzylamine afforded thioxalic acid dibenzylamide (5). On the other hand treatment of 2 with the same reagent afforded the corresponding benzylimino derivatives (6).Alkylation of 1 and 2 with ethyl bromoacetate and chloroacetamide yielded the corresponding S-alkyl derivatives (7) and (8), respectively.

1'-Derivatives of sucrose and their acid hydrolysis

1980 ◽  
Vol 33 (11) ◽  
pp. 2487 ◽  
Author(s):  
RD Guthrie ◽  
ID Jenkins ◽  
JJ Watters
Keyword(s):  
Acid Hydrolysis ◽  
Hydrolysis Of ◽  
Derivatives Of

Syntheses of 1'-chloro-1'-deoxy- and 1'-deoxy-sucrose are described. Several routes were investigated, the most successful being through 6,1',6'-tri-O-(2,4,6-trimethylbenzenesulfonyl)sucrose. Attempts to prepare 1'-deoxy-1'-fluorosucrose were unsuccessful. The rates of the acid-catalysed hydrolysis of 1'-chloro-1'-deoxysucrose and of 1'- deoxysucrose have been measured. These values are compared with that for sucrose itself. The mechanism of the hydrolyses is discussed.

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