2,2-Dimethylsuccinic acid derivatives in isoprenoid synthesis: a 2,2-dimethylvinyl anion equivalent in the synthesis of ar-atlantone, ar-turmerone, and prenylated aromatic compounds

1992 ◽  
Vol 70 (5) ◽  
pp. 1317-1322 ◽  
Author(s):  
George M. Strunz ◽  
Li Ya
Keyword(s):  
Aromatic Compounds ◽  
Dicarboxylic Acids ◽  
Lead Tetraacetate ◽  
Keto Acid ◽  
Acid Catalyzed ◽  
Crotonyl Chloride ◽  
Hydrolysis Of

The anion of methyl 2,2-dimethylsuccinate was alkylated with benzylic bromides to give the corresponding 3-substituted-2,2-dimethylsuccinates. Hydrolysis to the dicarboxylic acids, followed by bisdecarboxylation with lead tetraacetate, afforded 1-aryl-3-methyl-2-butenes, which are model prenylated aromatic compounds. Acylation of methyl 2,2-dimethylsuccinate with E-3-(4′-methylphenyl) crotonyl chloride gave the substituted succinate 9. Hydrolysis of the ester groups and acid-catalyzed decarboxylation of the resulting β-ketoacid produced the keto acid 10, which was decarboxylated by the Kochi method, furnishing ar-atlantone. Hydrogenation of 10 yielded 12, which on similar decarboxylation afforded ar-turmerone.

Water Soluble Steroids with Catalytic Substituents II. Synthesis of 3β-(4(5)-Imidazolyl)-5α-androstane-11β, 17β,-diamine and Comparison of its Catalytic Properties with Those of 17β-(4(5)-Imidazolyl)-5α-androstane-3β, 11β-diamine

1973 ◽  
Vol 51 (23) ◽  
pp. 3936-3942 ◽  
Author(s):  
J. Peter Guthrie ◽  
Yasutsugu Ueda
Keyword(s):  
Catalytic Properties ◽  
Lead Tetraacetate ◽  
Water Soluble ◽  
Keto Group ◽  
Rate Enhancement ◽  
Multistep Process ◽  
Acid Catalyzed ◽  
Hydrolysis Of

3β-(4(5)-Imidazolyl)-5α-androstane-11β,17β-diamine, 15, has been synthesized in a multistep process from adrenosterone, 2, starting with lithium ammonia reduction to give 11α,17β-dihydroxy-5α-androstan-3-one, 3, which was converted to its diacetate, 4. Ethynylation at the 3 keto group gave the ethynyl triol 5, purified as its11,17-diacetate 6. Acid catalyzed rearrangement of 6 gave 3-acetyl-5α-androst-2-ene-11α,17β-diol diacetate, 7. This was hydrogenated, and then subjected to base catalyzed hydrolysis and equilibration to give crystalline 3β-acetyl-5α-androstane-11α,17β-diol, 9, which was converted to 3β-acetoxyacetyl-5α-androstane-11α,17β-diol, 10, using lead tetraacetate. After hydrolysis to the triol, 11, the Weidenhagen reaction led to formation of 3β-imidazolyl-5α-androstane-11α,17β-diol, 12. Finally oxidation to the dione, 13, formation of the dioxime, 14, and hydrogénation give 15. As expected 15 is a better catalyst than 17β-(4(5)-imidazolyl-5α-androstane-3β,11β-diamine, 1, for the hydrolysis of aryl esters of acids with hydrophobic substituents, but the effect is small. With 1 there is a marked electrostatic rate enhancement or retardation when charged groups are present on the aryl esters; this effect is much smaller for 15.

The effect of polymeric and model imidazolium halides on the rate of hydrolysis of 4-acetoxy-3-nitrobenzoic acid

1985 ◽  
Vol 50 (4) ◽  
pp. 845-853 ◽  
Author(s):  
Miloslav Šorm ◽  
Miloslav Procházka ◽  
Jaroslav Kálal
Keyword(s):  
Catalyst Concentration ◽  
Low Molecular Weight ◽  
Imidazolium Chloride ◽  
First Order ◽  
Nitrobenzoic Acid ◽  
Rate Of Hydrolysis ◽  
Acid Catalyzed ◽  
Hydrolysis Of ◽  
Ethanol In Water ◽  
Direct Attack

The course of hydrolysis of an ester, 4-acetoxy-3-nitrobenzoic acid catalyzed with poly(1-methyl-3-allylimidazolium bromide) (IIa), poly[l-methyl-3-(2-propinyl)imidazolium chloride] (IIb) and poly[l-methyl-3-(2-methacryloyloxyethyl)imidazolium bromide] (IIc) in a 28.5% aqueous ethanol was investigated as a function of pH and compared with low-molecular weight models, viz., l-methyl-3-alkylimidazolium bromides (the alkyl group being methyl, propyl, and hexyl, resp). Polymers IIb, IIc possessed a higher activity at pH above 9, while the models were more active at a lower pH with a maximum at pH 7.67. The catalytic activity at the higher pH is attributed to an attack by the OH- group, while at the lower pH it is assigned to a direct attack of water on the substrate. The rate of hydrolysis of 4-acetoxy-3-nitrobenzoic acid is proportional to the catalyst concentration [IIc] and proceeds as a first-order reaction. The hydrolysis depends on the composition of the solvent and was highest at 28.5% (vol.) of ethanol in water. The hydrolysis of a neutral ester, 4-nitrophenyl acetate, was not accelerated by IIc.

Benzyl ethers of methyl α-D-glucopyranoside

1980 ◽  
Vol 45 (7) ◽  
pp. 1959-1963 ◽  
Author(s):  
Dušan Joniak ◽  
Božena Košíková ◽  
Ludmila Kosáková
Keyword(s):  
Kinetic Study ◽  
Spectrophotometric Determination ◽  
Reductive Cleavage ◽  
Ether Bond ◽  
Benzyl Ethers ◽  
Acid Catalyzed ◽  
Model Substances ◽  
Hydrolysis Of

Methyl 4-O-(3-methoxy-4-hydroxybenzyl) and methyl 4-O-(3,5-dimethoxy-4-hydroxybenzyl)-α-D-glucopyranoside and their 6-O-isomers were prepared as model substances for the ether lignin-saccharide bond by reductive cleavage of corresponding 4,6-O-benzylidene derivatives. Kinetic study of acid-catalyzed hydrolysis of the compounds prepared was carried out by spectrophotometric determination of the benzyl alcoholic groups set free, after their reaction with quinonemonochloroimide, and it showed the low stability of the p-hydroxybenzyl ether bond.

Cyclization and acid-catalyzed hydrolysis of O-benzoylbenzamidoximes

1986 ◽  
Vol 51 (12) ◽  
pp. 2786-2797
Author(s):  
František Grambal ◽  
Jan Lasovský
Keyword(s):  
Reaction Rate ◽  
Kinetic Isotope ◽  
Acid Base Equilibrium ◽  
Mineral Acids ◽  
Kinetics Of Formation ◽  
Acid Catalyzed ◽  
Ph Scale ◽  
Kinetics Of ◽  
Hydrolysis Of ◽  
Derivatives Of

Kinetics of formation of 1,2,4-oxadiazoles from 24 substitution derivatives of O-benzoylbenzamidoxime have been studied in sulphuric acid and aqueous ethanol media. It has been found that this medium requires introduction of the Hammett H0 function instead of the pH scale beginning as low as from 0.1% solutions of mineral acids. Effects of the acid concentration, ionic strength, and temperature on the reaction rate and on the kinetic isotope effect have been followed. From these dependences and from polar effects of substituents it was concluded that along with the cyclization to 1,2,4-oxadiazoles there proceeds hydrolysis to benzamidoxime and benzoic acid. The reaction is thermodynamically controlled by the acid-base equilibrium of the O-benzylated benzamidoximes.

ChemInform Abstract: ACID-CATALYZED HYDROLYSIS OF 3-ALKOXY-4′-SUBSTITUTED CROTONOPHENONES

1979 ◽  
Vol 10 (42) ◽  
Author(s):  
S. D. BRYNES ◽  
L. R. FEDOR
Keyword(s):  
Acid Catalyzed ◽  
Hydrolysis Of

scholarly journals Application of Polyimide‐based Microfluidic Devices on Acid‐catalyzed Hydrolysis of Dimethoxypropane

2021 ◽  
Vol 93 (5) ◽  
pp. 796-801
Author(s):  
Jens Bobers ◽  
Elisabeth Forys ◽  
Bastian Oldach ◽  
Norbert Kockmann
Keyword(s):  
Microfluidic Devices ◽  
Acid Catalyzed ◽  
Hydrolysis Of

A kinetic standard for precise calibration of spectrophotometer cell temperature.

1981 ◽  
Vol 27 (5) ◽  
pp. 753-755 ◽  
Author(s):  
P A Adams ◽  
M C Berman
Keyword(s):  
Temperature Dependence ◽  
Rate Constants ◽  
Cell Temperature ◽  
First Order ◽  
Order Rate ◽  
Acid Catalyzed ◽  
Pseudo First Order ◽  
Hydrolysis Of

Abstract We describe a simple, highly reproducible kinetic technique for precisely measuring temperature in spectrophotometric systems having reaction cells that are inaccessible to conventional temperature probes. The method is based on the temperature dependence of pseudo-first-order rate constants for the acid-catalyzed hydrolysis of N-o-tolyl-D-glucosylamine. Temperatures of reaction cuvette contents are measured with a precision of +/- 0.05 degrees C (1 SD).

Oligomeric stannoxanes

1968 ◽  
Vol 46 (14) ◽  
pp. 2409-2413 ◽  
Author(s):  
Shmuel Migdal ◽  
David Gertner ◽  
Albert Zilkha
Keyword(s):  
Dicarboxylic Acids ◽  
Molar Ratio ◽  
Sodium Salts ◽  
Interfacial Conditions ◽  
Organotin Polyesters ◽  
Basic Hydrolysis ◽  
Hydrolysis Of

The controlled basic hydrolysis of tetrabutyl-1,3-dichlorodistannoxane under interfacial conditions was found to lead to α,ω-dichlorooligostannoxanes, Cl(SnBu2O)nSnBu2Cl, n being controlled by the molar ratio of base to distannoxane. These oligostannoxanes were identical with those prepared by other methods. They were used in the preparation of oligostannoxane dicarboxylates and organotin polyesters, having stannoxane recurring units in their backbone, by reaction with the sodium salts of mono- or dicarboxylic acids under interfacial conditions.

Lewis Acid Catalyzed Highly Selective Halogenation of Aromatic Compounds

Synlett ◽  
2005 ◽  
pp. 2837-2842 ◽  
Author(s):  
Hisashi Yamamoto ◽  
Yanhua Zhang ◽  
Kazutaka Shibatomi
Keyword(s):  
Lewis Acid ◽  
Aromatic Compounds ◽  
Acid Catalyzed
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