3938-95-2Relevant academic research and scientific papers
Exploring the catalytic activity of Lewis-acidic uranyl complexes in the nucleophilic acyl substitution of acid anhydrides
Takao, Koichiro,Akashi, Shin
, p. 12201 - 12207 (2017/03/08)
The catalytic activities of several uranyl complexes, such as N,N′-disalicylidene-o-phenelyenediaminato(ethanol)dioxouranium(vi) (UO2(salophen)EtOH), bis(dibenzoylmethanato)(ethanol)dioxouranium(vi) (UO2(dbm)2EtOH), pentakis(N,N-dimethylformamide)dioxouranium(vi) ([UO2(DMF)5]2+), and tetrakis(triphenylphosphine oxide)dioxouranium(vi) ([UO2(OPPh3)4]2+), were examined in the nucleophilic acyl substitution of acid anhydrides. Among them, [UO2(OPPh3)4]2+ was the most efficient to give ethyl acetate and acetic acid from acetic anhydride (Ac2O) and ethanol, and was resistant towards decomposition during the catalytic reaction. Several nucleophiles were also subjected to the catalytic acylation reaction using acetic and pivalic anhydride. Kinetic and spectroscopic studies suggested that [UO2(OPPh3)4]2+ interacts with Ac2O to form [UO2(Ac2O)(OPPh3)3]2+. Interaction of this actual catalyst with additional Ac2O determines the rate of the overall nucleophilic acyl substitution reaction.
Chemoselective CaO-mediated acylation of alcohols and amines in 2-methyltetrahydrofuran
Pace, Vittorio,Hoyos, Pilar,Alcántara, Andrés R.,Holzer, Wolfgang
, p. 905 - 910 (2013/07/27)
Calcium oxide is proposed as an innocuous acid scavenger for the chemoselective synthesis of amide- and ester-type compounds. Although these molecules have wide spread applications in organic and pharmaceutical chemistry, and a large number of routes have been designed for their synthesis, the development of more efficient and environmentally friendly acylation strategies remains an ongoing challenge. The use of CaO allows for the stoichiometric acylation of primary alcohols in the presence of phenols or tertiary alcohols; amines can also be subjected to acylation reactions in the presence of hydroxyl groups. Chirality is obtained through acylation if the starting material is an optically pure alcohol or if a chiral acylating agent is used. Furthermore, the use of 2-methyltetrahydrofuran (2-MeTHF), a more ecofriendly solvent, leads to maximized yields. This protocol is successfully applied to the synthesis of an interesting N-aryloxazolidin-2-one intermediate for the preparation of linezolid-type compounds.
Double molecular recognition with aminoorganoboron complexes: Selective alcoholysis of β-dicarbonyl derivatives
Oishi, Shunsuke,Saito, Susumu
supporting information; experimental part, p. 5395 - 5399 (2012/06/18)
Double duty: Aminoorganoboron (AOB) complexes recognize alcohol and β-dicarbonyl units, and thereby facilitate chemo- and site-selective alcoholysis of the latter (see scheme). The complex activates both reaction partners. This strategy enables C-C, C-N, and C-O bond cleavage in addition/elimination reactions under near neutral pH conditions and provides a new method for functional group conversions. Copyright
A mild and efficient chemoselective protection of primary alcohols as pivaloyl esters using La(NO3)3·6H2O as a catalyst under solvent-free conditions
Prabhakar,Suryakiran,Venkateswarlu
, p. 732 - 733 (2008/02/09)
Primary alcohols are selectively and efficiently protected as their pivaloyl esters with pivaloyl chloride in the presence of catalytic amounts of La(NO3)3·6H2O at room temperature under solvent-free conditions in excellent yields. Copyright
Alpha- haloenamine reagents
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, (2008/06/13)
The present invention describes immobilized haloenamine reagents, immobilized tertiary amides, methods for their preparation, and methods of use.
The Pd3(dppm)3 (CO)2+ cluster: An efficient electrochemically assisted Lewis acid catalyst for the fluorination and alcoholysis of acyl chlorides
Lemaitre, Frederic,Lucas, Dominique,Mugnier, Yves,Harvey, Pierre D.
, p. 7537 - 7540 (2007/10/03)
The dicationic palladium cluster Pd3(dppm)3-(CO)2+ (dppm = bis(diphenylphosphino)methane) reacts with acid chlorides RCOCl (R = n-C6H13, t-Bu, Ph) to afford quantitatively the chloride adduct Pd3(dppm)3(CO)(Cl)+ and the acyl cation RCO+ as the organic counterpart. The dicationic reactive cluster can be reformed by electrolyzing the chloride complex with a copper anode leaving CuCl as a byproduct. The combination of these two reactions provides an electrocatalytic way to form the acylium from the acid chloride. Indeed, in CH2Cl2, 0.2 M NBu4PF6, or NBu4BF4, the electrolysis of the acid chloride in the presence of a catalytic amount of the cluster (1%) gives in good yields the acid fluoride RCOF, arising from the coupling of the acylium with a F- issued from the fluorinated supporting electrolyte. Alternatively, in CH2Cl2 or 0.2 M NBu4ClO4, by operating with an alcohol R′OH as the nucleophile, the electrolysis gives the ester RC(O)OR′ as the only final product.
Hydroesterification of tert-butyl alcohol in room temperature ionic liquids
Qiao, Kun,Deng, Youquan
, p. 667 - 670 (2007/10/03)
Hydroesterification of tert-butyl alcohol with ethanol catalyzed by transition metal triphenylphosphine complexes in the presence of p-toluenesulfonic acid was investigated using room temperature ionic liquids as the reaction medium at 373-413 K and 3-6 MPa of CO. In comparison with the organic solvents as reaction medium, higher conversion was achieved and ethyl tert-valerate could be directly formed in the ionic liquid medium. The products could be separated from the ionic liquids easily due to their immiscibility in this medium.
Syntheses based on monocarbon molecules: III.1 hydroethoxycarbonylation of 2-methylpropene in the presence of palladium phosphine complexes at a low pressure of carbon monoxide
Suerbaev,Shalmagambetov,Zhubanov
, p. 1924 - 1926 (2007/10/03)
Among the catalytic systems PdCl2(PPh3)2, PdCl2(PPh3)2-PPh3, PdCl2(PPh3)2-TsOH, PdCl2(PPh3)2-PPh3-TsOH, and PdCl2-PPh3-TsOH, the latter is the best catalyst for hydroethoxycarbonylation of 2-methylpentene at a low pressure of carbon monoxide.
Reversible protonation of isobutane in liquid superacids in competition with protolytic ionization
Sommer, Jean,Bukala, Jozef,Hachoumy, Mohammed,Jost, Roland
, p. 3274 - 3279 (2007/10/03)
The deuterium distribution observed in isobutane recovered after short contact times with the DF-SbF5 superacid at 0°C shows that a very fast reversible protonation of all C-H bonds occurs before ionization of the alkane, in accord with the Olah σ-basicity concept. Comparison of the amounts of hydrogen with the amount of tert-butyl ions generated during ionization shows that the reaction is purely protolytic in HF containing up to 20 mol % SbF5, but becomes oxidative at higher concentrations.
Reaction enthalpy of nucleophilic substitution of ethyl iodide in acetonitrile and its mechanistic significance
Kondo, Yasuhiko,Tsukamoto, Tamio,Kimura, Naoko
, p. 1765 - 1769 (2007/10/03)
Enthalpies of reaction for nucleophilic substitution of ethyl iodide have systematically been determined in acetonitrile. Through the concurrent analysis of empirical correlations between the reaction enthalpies and the specific interaction enthalpies for relevant anions with those between the logarithmic rates and the specific interaction enthalpies, partial desolvation accompanying activation has been deduced to be the major contributor to activation thermodynamic parameters, while the propensity of the reacting central atom in the nucleophilic anion plays a crucial role in determining reaction thermodynamic parameters. Semi-empirical molecular orbital calculations have supported these ideas. The application of the Marcus equation to the analysis of reaction characteristics in these reactions is discussed.
