ChemInform Abstract: Gold(I)/Chiral Broensted Acid Catalyzed Enantioselective Hydroamination-Hydroarylation of Alkynes: The Effect of a Remote Hydroxyl Group on the Reactivity and Enantioselectivity.

ChemInform ◽  
2015 ◽  
Vol 46 (23) ◽  
pp. no-no
Author(s):  
Valmik S. Shinde ◽  
Manoj V. Mane ◽  
Kumar Vanka ◽  
Arijit Mallick ◽  
Nitin T. Patil
Keyword(s):  
Hydroxyl Group ◽  
Acid Catalyzed

THE EPIMERIZATION OF DELCOSINE

1961 ◽  
Vol 39 (8) ◽  
pp. 1579-1587 ◽  
Author(s):  
Vinko Skarić ◽  
Léo Marion
Keyword(s):  
Infrared Spectra ◽  
Potassium Hydroxide ◽  
Methoxyl Group ◽  
Hydroxyl Group ◽  
Sodium Amalgam ◽  
Acid Catalyzed ◽  
Nitrogen Ring

Delcosine has been assigned tentatively the same C—N skeleton as lycoctonine. In lycoctonine, ring A carries at C-1 a methoxyl group which is directed away from the nitrogen ring. In delcosine, C-1 carries a hydroxyl group which has the opposite configuration and is directed towards the nitrogen. An attempt to correlate the two structures first involves epimerization at C-1 in delcosine. This has been carried out by oxidation of desethyldelcosine to an azomethine, the ethiodide of which, by the action of methanolic potassium hydroxide, is converted to oxo-1-epidelcosine in two steps. Oxo-1-epidelcosine in an acid-catalyzed rearrangement is transformed to a pinacone which, after methylation, gives O,O-dimethyl-anhydro-oxo-1-epidelcosine. This compound was compared with O-methylanhydro-oxolycoctonine, prepared from oxolycoctonine, but was not identical. Removal of a methoxyl, which in each compound is ortho to a carbonyl, by the action of sodium amalgam, produced O,O-dimethyl-6-desmethoxy-anhydro-oxo-1-epidelcosine and O-methyl-6-desmethoxy-anhydro-oxolycoctonine, which are not identical, but show in their infrared spectra much less dissimilarity than the spectra of the pair of compounds from which they were derived. These results are discussed in terms of the structure of delcosine.

The proton affinities and deprotonation enthalpies of β-D-fructopyranose and α-L-sorbopyranose

1991 ◽  
Vol 69 (12) ◽  
pp. 1917-1928 ◽  
Author(s):  
Robert J. Woods ◽  
Walter A. Szarek ◽  
Vedene H. Smith Jr.
Keyword(s):  
Hydrogen Bonding ◽  
Oxygen Atom ◽  
Intramolecular Hydrogen Bonding ◽  
Hydroxyl Group ◽  
Proton Affinities ◽  
Naturally Occurring ◽  
Acid Catalyzed ◽  
Acids And Bases ◽  
Intramolecular Hydrogen ◽  
Hydrolysis Of

The proton affinities (PAs) and deprotonation enthalpies (DPEs) were calculated for the pyranoid forms of two naturally occurring sugars, D-fructose and L-sorbose. In both molecules the PAs of the primary hydroxyl group (HO-1), the anomeric hydroxyl group (HO-2), and the ring-oxygen atom (O-6) were calculated, as were the DPEs of HO-1 and HO-2. The stabilities of the conjugate acids and bases of these sugars are enhanced by the presence of intramolecular hydrogen bonding, a feature that is significant in explaining the differences in sweetness and the rates of mutarotation of the title compounds, as well as the differences in the rates of acid-catalyzed hydrolysis of ketopyranosides. Key words: proton affinity, deprotonation enthalpy, ab initio calculations, AM1, hexuloses.

EXPLORING THE POTENTIAL ENERGY SURFACE OF THE CATALYZED ISOMERIZATION OF NITROSOMETHANE TO FORMALDOXIME

2007 ◽  
Vol 06 (01) ◽  
pp. 187-195 ◽  
Author(s):  
GUO-MING LIANG ◽  
YI REN ◽  
SAN-YAN CHU ◽  
NING-BEW WONG
Keyword(s):  
Activation Energy ◽  
Formic Acid ◽  
Energy Surface ◽  
Reaction Pathway ◽  
Hydroxyl Group ◽  
Rate Determining Step ◽  
Reaction Channels ◽  
Acid Catalyzed ◽  
Favorable Reaction ◽  
The One

The mechanism of the isomerization of nitrosomethane to formaldoxime catalyzed by neutral molecule ( H 2 O and HCOOH ) has been investigated at the level of B3LYP/6-311+G**. Calculated results indicate that the rearrangement from nitrosomethane to more stable trans-formaldoxime can proceed via two different reaction channels, but the favorable reaction pathway catalyzed by water and formic acid is different from the one in the catalyst-free reaction. It is more favorable that the tautomeric reaction involves the formation of cis-formaldoxime and a subsequent rotation about the N – O bond to form trans-formaldoxime in the catalyzed reaction. The activation energy of rate-determining step was reduced from 197.9 kJ/mol to 138.7 kJ/mol in the water-catalyzed reaction and 79.6 kJ/mol in the formic acid-catalyzed reaction, respectively, due to the catalysis of hydroxylic groups, but the catalysis of more acidic hydroxyl group in the latter system has been shown to be more efficient.

Mechanism and Stereochemistry of the Hydrolysis of 4-Arylamino-1,2,3,4- tetrahydroquinaldines

1974 ◽  
Vol 52 (6) ◽  
pp. 884-887 ◽  
Author(s):  
T. P. Forrest ◽  
G. A. Dauphinee ◽  
W. F. Miles
Keyword(s):  
Nitrogen Atom ◽  
Equilibrium Mixture ◽  
Hydroxyl Group ◽  
Amino Group ◽  
Heterocyclic Nitrogen ◽  
Carbonium Ion ◽  
Kinetically Controlled ◽  
Leaving Group ◽  
Acid Catalyzed ◽  
Hydrolysis Of

Rates of acid-catalyzed hydrolysis of the benzylic amino group in stereoisomers of 4-arylamino-1,2,3,4-tetrahydroquinaldines have been determined by n.m.r. spectroscopy. Those isomers which have a pseudo-axial leaving group react more rapidly than those with a pseudo-equatorial leaving group, forming in each case the isomer with a pseudo-axial hydroxyl group as the kinetically controlled product. This product is converted in time to an equilibrium mixture of the two stereoisomeric alcohols. The reaction is inhibited by excess acid and appears to proceed through an intermediate carbonium ion which is stabilized by the heterocyclic nitrogen atom.

Reactions of thiourea with chloro- and bromoacetic acids

1980 ◽  
Vol 45 (1) ◽  
pp. 263-268 ◽  
Author(s):  
Jaromír Kaválek ◽  
Said El-Bahaie ◽  
Vojeslav Štěrba
Keyword(s):  
Chloroacetic Acid ◽  
Hydroxyl Group ◽  
Salt Formation ◽  
Sulphur Atom ◽  
Bromoacetic Acid ◽  
Tetrahedral Intermediate ◽  
Acid Catalyzed ◽  
Rate Limiting

The reaction of chloroacetic acid with thiourea represents an SN2 substitution of chlorine by sulphur atom and is about two orders of magnitude slower than that of bromoacetic acid. Chloroacetate ion reacts slower than chloroacetic acid only about 30%. The acid catalyzed splitting off of hydroxyl group from the formed tetrahedral intermediate is rate-limiting in the cyclization of the S-carboxylatomethyleneisothiouronium salt, formation of the intermediate being rate-limiting below pH 2.

Hydroxyl Group-Directed, Tartaric Acid-Catalyzed Synthesis of meta-Functionalized Aryl Ethers and Phenols through Domino Conjugate Addition/Aromatization of para-Quinols

2021 ◽  
Author(s):  
Guoshu Chen ◽  
Jia-Hui Li ◽  
Shujie Chen ◽  
Wen-Xia Lin ◽  
Hai Ren ◽  
...  
Keyword(s):  
Tartaric Acid ◽  
Conjugate Addition ◽  
Single Step ◽  
Hydroxyl Group ◽  
Alkyl Ether ◽  
Three Component Reaction ◽  
Organoboronic Acids ◽  
Acid Catalyzed ◽  
Aryl Ethers

A tartaric acid-catalyzed three-component reaction of para-quinols, organoboronic acids, and alcohols is reported, leading to meta-alkenylated aryl alkyl ether in a single step. Moreover, meta-functionalized phenols could also be obtained...

ChemInform Abstract: Broensted Acid-Catalyzed Intramolecular Nucleophilic Substitution of the Hydroxyl Group in Stereogenic Alcohols with Chirality Transfer.

ChemInform ◽  
2015 ◽  
Vol 46 (38) ◽  
pp. no-no
Author(s):  
Anon Bunrit ◽  
Christian Dahlstrand ◽  
Sandra K. Olsson ◽  
Pemikar Srifa ◽  
Genping Huang ◽  
...  
Keyword(s):  
Nucleophilic Substitution ◽  
Hydroxyl Group ◽  
Chirality Transfer ◽  
Intramolecular Nucleophilic Substitution ◽  
Acid Catalyzed
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