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Erratum: Internal redox amidation of α,β-unsaturated aldehydes in ionic liquids. the electrochemical route (Electrochimica Acta (2013) 89:(692-699))
No full textCarbon dioxide as carbon source: Activation via electrogenerated O(2)(center dot-) in ionic liquids
No full text"The activation of carbon dioxide has been obtained in O(2)\/CO(2) saturated ionic liquids, via electrochemically generated O(2)(center dot-), at a less negative potential than the one of the direct cathodic reduction of CO(2). This electrochemical activation has been applied to the C-N bond formation from amines and carbon dioxide in the synthesis of organic carbamates. A competitive reaction between electrogenerated superoxide ion and imidazolium cations yielding 2-imidazolones has been pointed out. This procedure allows to avoid the utilization of volatile and toxic organic solvents, supporting electrolytes and catalysts.
Activation of Elemental Sulfur by Electrogenerated Cyanomethyl Anion: Synthesis of Substituted 2-Aminothiophenes by the Gewald Reaction
No full textThe activation of elemental sulfur (S(8)) has been achieved by means of electrogenerated cyanomethyl anion [easily obtained by galvanostatic reduction from acetonitrile/tetraethylammonium hexafluorophosphate (MeCN-Et(4)NPF(6))]. The "activated" sulfur reacted with ylidenernalononitriles to give substituted 2-aminothiophenes in very high yields. This variation of the Gewald reaction has been carried out using only catalytic amounts of electricity and supporting electrolyte. A proposed mechanism for the interaction between S(8) and cyanomethyl anion is described
Electrogenerated N-Heterocyclic Carbenes in the Room Temperature Parent Ionic Liquid as an Efficient Medium for Transesterification/Acylation Reactions
No full textN-Heterocyclic carbenes (NHCs), generated by electrochemical reduction under galvanostatic control of 1,3-dialkylimidazolium-based ionic liquids, were employed as catalysts in transesterification reactions in the parent, room temperature ionic liquids (RTILs) as solvents, without the utilisation of any volatile organic solvent or base. The reaction between isopropenyl or ethyl acetate and an alcohol (not efficient in the absence of catalyst) was induced by the presence of an electrogenerated NHC, which seems to assist the proton transfer from the alcohol to the ester, yielding the corresponding acetate. The reaction also proceeds with methyl nicotinate as starting ester and 2-(diethylamino)ethanol or benzyl alcohol as alcohols and leads to the corresponding biologically active compounds, nicametate and benzyl nicotinate, in good yields. All products were isolated in good to excellent yields and complete recyclability of the ionic liquid as solvent has been demonstrated
Geminal Ionic Liquids: an electrochemical approach to investigate their reactivity and stability vs. traditional monocationic ionic liquids
No full textThe dual role of ionic liquid BmimBF4, precursor of N-heterocyclic carbene and solvent, in the oxidative esterification of aldehydes
No full textElectrogenerated N- heterocyclic carbenes: N-functionalization of benzoxazolones
No full textA simple electrochemical procedure for the N-acylation and N-alkylation of benzoxazol-2(3H)-ones has been set up via electrolysis of an ionic liquid containing a benzoxazolone followed by addition of saturated or unsaturated anhydrides or alkyl halides. The electrochemically induced N-functionalization of benzoxazol-2(3H)-ones works very well in all tested ionic liquids, avoiding the use of volatile organic solvents. The N-acyl and N-alkyl derivatives of benzoxazol-2(3H)-ones were isolated in good to excellent yields; moreover, the ionic liquid has been reused fivefold maintaining the high yield of the products
Two different selective ways in the deprotonation of β-bromopropionanilides: β-lactams or acrylanilides formation
Full text linkThe reactivity of 3-bromo-N-(p-bromophenyl)propanamide with different bases in an ionic liquid (BMImBF4) and in acetonitrile (ACN) was studied. Two possible deprotonation sites are present in this molecule, leading to different products. When the NH group is deprotonated, a β-lactam is obtained after internal halide displacement; when the CH2 in alpha to the carbonyl is deprotonated, the corresponding acrylanilide is formed. This study allowed determining the experimental conditions to obtain selectively and in high yields both products starting from the same molecule. In particular, to obtain the acrylanilide Et3N in ACN is to be used, while to obtain selectively the β-lactam ring the base must be generated by cathodic reduction of a DMF or ACN-Et4NBF4 solution. These reactions were extended to other β-bromopropionanilides, allowing to easily synthesize both β-lactams and acrylanilides, molecules having noteworthy biological activities
Umpolung reactions in an ionic liquid catalyzed by electrogenerated N-heterocyclic carbenes. Synthesis of saturated esters from activated a,b-unsaturated aldehydes
No full textThe umpolung reaction of a,b-unsaturated aldehydes to saturated esters has been carried out in an ionic liquid by organocatalysis of electrogenerated NHC. The roles of solvent, precatalyst and proton donor of the ionic liquid have been verified and good to high yields of esters have been obtained using a ‘‘green’’ and mild methodology
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