Hydroxamic acids. II. The acetylation of O-alkylhydroxamic acids

1969 ◽  
Vol 22 (1) ◽  
pp. 161
Author(s):  
MTW Hearn ◽  
AD Ward
Keyword(s):  
Hydroxamic Acid ◽  
Acetyl Derivative ◽  
Hydroxamic Acids ◽  
Steric Effects ◽  
High Yield ◽  
Acid Form ◽  
Acid System ◽  
Mild Conditions ◽  
Acidic Proton ◽  
Electronic And Steric Effects

O-Alkylhydroxamic acids are readily acetylated, in high yield, under mild conditions. Aliphatic O-alkylhydroxamic acids yield only one product, shown to be the N-acetyl derivative. O-Alkylarylhydroxamic acids form both the O- and N- acetyl isomers; the ratio of these isomers depends on electronic and steric effects. Ultraviolet spectral data indicate that the salts of O-alkylarylhydroxamic acids exist predominantly in the hydroximic acid form; however, it is not possible to decide which is the acidic proton of the hydroxamic acid system. The nature of the cation in the salts of O-alkylhydroxamic acids is important in determining the site of acetylation.

scholarly journals Ligand-Controlled Regiodivergence in Nickel-Catalyzed Hydroarylation and Hydroalkenylation of Alkenyl Carboxylic Acids

2020 ◽  
Author(s):  
Zi-Qi Li ◽  
Yue Fu ◽  
Ruohan Deng ◽  
Van Tran ◽  
Yang Gao ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Transition State ◽  
Carboxylic Acids ◽  
Alkyl Group ◽  
Steric Effects ◽  
High Yield ◽  
Mechanistic Studies ◽  
Ligand Environment ◽  
Ligand Free ◽  
Electronic And Steric Effects

<div>A nickel-catalyzed regiodivergent hydroarylation and hydroalkenylation of unactivated alkenyl carboxylic acids is reported, whereby the ligand environment around the metal center dictates the regiochemical outcome. Markovnikov hydrofunctionalization products are obtained under mild ligand-free conditions, with up to 99% yield and >20:1 selectivity. Alternatively, anti-Markovnikov products can be accessed with a novel 4,4-disubstituted Pyrox ligand in excellent yield and >20:1 selectivity. Both electronic and steric effects on the ligand contribute to the high yield and selectivity. Mechanistic studies suggest a change in the turnover-limiting and selectivity-determining step induced by the optimal ligand. DFT calculations reveal that in the anti-Markovnikov pathway, repulsion between the ligand and the alkyl group is minimized (by virtue of it being 1° versus 2°) in the rate- and regioselectivity-determining transmetalation transition state. <br></div>

scholarly journals Ligand-Controlled Regiodivergence in Nickel-Catalyzed Hydroarylation and Hydroalkenylation of Alkenyl Carboxylic Acids

2020 ◽  
Author(s):  
Zi-Qi Li ◽  
Yue Fu ◽  
Ruohan Deng ◽  
Van Tran ◽  
Yang Gao ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Transition State ◽  
Carboxylic Acids ◽  
Alkyl Group ◽  
Steric Effects ◽  
High Yield ◽  
Mechanistic Studies ◽  
Ligand Environment ◽  
Ligand Free ◽  
Electronic And Steric Effects

<div>A nickel-catalyzed regiodivergent hydroarylation and hydroalkenylation of unactivated alkenyl carboxylic acids is reported, whereby the ligand environment around the metal center dictates the regiochemical outcome. Markovnikov hydrofunctionalization products are obtained under mild ligand-free conditions, with up to 99% yield and >20:1 selectivity. Alternatively, anti-Markovnikov products can be accessed with a novel 4,4-disubstituted Pyrox ligand in excellent yield and >20:1 selectivity. Both electronic and steric effects on the ligand contribute to the high yield and selectivity. Mechanistic studies suggest a change in the turnover-limiting and selectivity-determining step induced by the optimal ligand. DFT calculations reveal that in the anti-Markovnikov pathway, repulsion between the ligand and the alkyl group is minimized (by virtue of it being 1° versus 2°) in the rate- and regioselectivity-determining transmetalation transition state. <br></div>

scholarly journals Hydrolysis of Hydroxamic Acid Complexants in the Presence of Non-Oxidizing Metal Ions

2012 ◽  
Vol 1383 ◽  
Author(s):  
Scott Edwards ◽  
Fabrice Andrieux ◽  
Colin Boxall ◽  
Robin Taylor ◽  
David Woodhead
Keyword(s):  
Metal Ions ◽  
Organic Compounds ◽  
Rate Constants ◽  
Hydroxamic Acid ◽  
Hydroxamic Acids ◽  
Acid System ◽  
Nuclear Fuel Reprocessing ◽  
System 1 ◽  
Hydrolysis Of ◽  
Fuel Reprocessing

ABSTRACTSimple Hydroxamic acids (XHAs) are salt free, organic compounds with affinities for hard cations such as Fe3+, Np4+, Pu4+ and have been identified as suitable reagents for the control of Pu and Np in advanced nuclear fuel reprocessing. Building upon previous work on the neptunium(IV)-formohydroxamic(FHA) acid system [1], a model that describes the hydrolysis of the acetohydroxamate moiety has been extended to include hydrolysis of bishydroxamatoneptunium(IV) complex. The model has been used to determine the rate constants for hydrolysis of mono- and bis-acetohydroxamatoneptunium(IV) at 25 °C, which were found to be 1.0×10-5 dm3 mol-1 s-1 and 5.0×10-5 dm3 mol-1 s-1, respectively.

Electronic and steric effects on the intramolecular Schmidt reaction of alkyl azides with secondary benzyl alcohols

Tetrahedron ◽  
2014 ◽  
Vol 70 (3) ◽  
pp. 643-649 ◽  
Author(s):  
Xiaowei Sun ◽  
Chengzhe Gao ◽  
Fan Zhang ◽  
Zhuang Song ◽  
Lingyi Kong ◽  
...  
Keyword(s):  
Steric Effects ◽  
Schmidt Reaction ◽  
Benzyl Alcohols ◽  
Alkyl Azides ◽  
Electronic And Steric Effects

Eco-Friendly Synthesis of Sulphonic Acid Oxime Esters Catalyzed by 2-(1H-Benzotriazole-1-yl)-1,1,3,3-Tetramethyluronium Tetrafluoroborate

2014 ◽  
Vol 525 ◽  
pp. 93-96
Author(s):  
Wei Shi ◽  
Ji Ming Zhang ◽  
Jian Hua Zhou ◽  
Jian Hua Zhou ◽  
Song Song Ding
Keyword(s):  
High Selectivity ◽  
Sulphonic Acid ◽  
Present Approach ◽  
High Yield ◽  
Facile Synthesis ◽  
Reaction Duration ◽  
Mild Conditions ◽  
Environmental Friendly

Herein we describle a facile synthesis of sulphonic acid oxime esters in acetonitrile from the corresponding sulphonic acids and oximes catalyzed by the environmental friendly 2-(1H-benzotriazole-1-yl)-1,1,3,3-tetramethyluronium tetrafluoroborate (TBTU) in the presence of triethylamine (TEA) under mild conditions. The present approach offers the advantages of a clean reaction, simple methodology, employing readily available catalyst, short reaction duration, high selectivity and high yield.

The Reactions of Substituted Germyl- and Silylhydrazines with BX3 and CY2 Acceptor Species

1972 ◽  
Vol 50 (4) ◽  
pp. 562-566 ◽  
Author(s):  
L. K. Peterson ◽  
K. I. Thé
Keyword(s):  
Molecular Weight ◽  
Nitrogen Atom ◽  
Low Temperatures ◽  
Adduct Formation ◽  
Steric Effects ◽  
Reaction Products ◽  
Hydrazine Derivatives ◽  
Basic Catalysts ◽  
Series Of Experiments ◽  
Electronic And Steric Effects

Boron trimethyl reacts with each of the organometalloid-hydrazine derivatives Me2NN(R)GeMe3 (R = H, Me, SiMe3) except Me2NN(SiMe3)GeMe3, and with Me2NNHSiMe3, forming 1:1 adducts. With Me2NN(SiMe3)GeMe3 and BMe3, no adduct was formed even at low temperatures. On the basis of p.m.r. spectra, the metalloid-substituted nitrogen atom rather than the terminal nitrogen, is indicated as the basic center at which adduct formation occurs. With BF3, the Si—N and Ge—N bonds of the hydrazine derivatives were cleaved, again indicating attack at the central nitrogen atom. In a series of experiments involving CY2 (Y = O, S) and Me2NN(R)MMe3 (R = H, Me, SiMe3; M = Si, Ge), reaction occurred readily for R = H, but less readily for R = Me and for the compound Me2NN(GeMe3)2, while no reaction was observed for the compounds Me2NN(SiMe3)2 and Me2NN(SiMe3)GeMe3, even when heat or basic catalysts were employed. Reaction products, carbamate and thiocarbamate derivatives, Me2NN(R)C(Y)YMMe3, were characterized on the basis molecular weight, i.r., p.m.r., and mass spectroscopy, and m.p. data. Ease of formation is discussed in terms of electronic and steric effects.

Highly Stereo- and Regioselective Allylations Catalyzed by Mo−Pyridylamide Complexes:  Electronic and Steric Effects of the Ligand

2000 ◽  
Vol 65 (18) ◽  
pp. 5868-5870 ◽  
Author(s):  
Oscar Belda ◽  
Nils-Fredrik Kaiser ◽  
Ulf Bremberg ◽  
Mats Larhed ◽  
Anders Hallberg ◽  
...  
Keyword(s):  
Steric Effects ◽  
Electronic And Steric Effects
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