Belen Batanero

Electrosynthesis of 3-chloro-4-substituted-coumarins

A facile synthesis of 3-chloro-4-substituted-coumarins (2) was performed in good yield by cathodic reduction of 2-acyl(or aroyl)phenyltrichloroacetates (1). When 2-acetylphenyldichloroacetate (3) was employed, a mixture of 3-chloro-4-methyl-coumarin (2a) and 4-methyl-coumarin (4) was obtained. The cleavage of the ester was the main reaction when 2-acetylphenylchloroacetate was reduced.

Electrochemical synthesis of 3-phenylcinnamonitrile by reduction of benzophenone in acetonitrile

Abstract The electrochemical cyanomethylation of benzophenone in acetonitrile was investigated as an interesting way of synthesizing high yield of 3-phenylcinnamonitrile (55% for 50% of theoretical circulated charge). This synthetic method uses the benzophenone radical-anion as a strong electrogenerated base to abstract a proton from the solvent and obtain the nucleophile − CH 2 CN. This anion is capable of yielding cyanomethylated products very easily. In our case the reaction of this anion with benzophenone yields 3-phenylcinnamonitrile in a father–son like mechanism.

A new proposed mechanism for the cathodic reduction of a carbon–chlorine bond in 2-acetylphenyltrichloroacetate

Abstract The cathodic reduction of 2-acetylphenyltrichloroacetate at a controlled potential of −0.5 V (vs SCE) yields 3,3-dichloro-4-hydroxy-4-methyl-3,4-dihydrocoumarin. The charge consumption is 1e−/substrate molecule, which is in agreement with a non-conventional R–X→R−+X mechanism.

One-Pot Formation of 1,3,4-Oxadiazol-2(3H)-ones and Dibenzo[c,e]azepines by Concomitant Cathodic Reduction of Diazonium Salts and Phenanthrenequinones

The one-pot concomitant electrochemical reduction of phenanthrenequinones (1, 2) and arenediazonium salts (3a-f) led to the formation of 1,3,4-oxadiazol-2(3H)-ones (4a-f, 5a) and dibenzo[c,e]azepines (6a-f) when N-methylformamide was used as the solvent. A new pathway, different from those previously described with other aprotic solvents, is proposed. The experimental data support a radical mechanism for the electrochemical process followed by an internal rearrangement to give the products.

Microwave reaction of diazonium salts with nitriles

A series of aryldiazonium tetrafluorborates dissolved in nitriles have been converted into the corresponding anilides in almost quantitative yield in 1 min by microwave irradiation. When bromoacetonitrile was used, 2,4-bis(bromophenyl)-quinazoline was formed. The reaction of malononitrile with the diazonium salt, in DMF as a solvent, afforded 2-(dimethylaminomethylene) malononitrile and phenylhydrazone propanedinitrile.

Synthesis of 1,2,3-triazoles

4-Phenyl-1-(p-toluenesulfonamido)-1,2,3-triazole (1) is obtained when phenacyl halides react with tosyl hydrazide in one-pot process.

Cathodic reduction of phenacyl thiocyanate

Abstract The cathodic reduction of phenacyl thiocyanate in aprotic medium leads to an enolate, which acts as nucleophile in addition or substitution reactions as well as electrogenerated base. The products of these reactions were isolated and identified as 2,4-diphenylthiophene, 1,4-diphenyl-1,4-butanedione, 1,5-diphenyl-3-benzoyl-1,5-pentanedione, trans-1,2,3-tribenzoyl cyclopropane and acetophenone.

Preparation of novel mesoionic compounds : a reversible photochromic process

Abstract The 3,7-diaryl-2H-imidazo[2,1-b][1,3,4]oxadiazines 1 in sunlight undergo a reversible transformation into mesoionic imidazole compounds 2.

Stereoselective Cyclopropanation to Homoquinones from Phenacyl Carbenes Obtained through Quinone-Electrogenerated Bases

A series of new (E) and (Z)-benzoyl-homoquinones have been prepared in good yield by the parent quinone-electrogenerated base (EGB) in the presence of α-bromoacetophenones or α-bromopropiophenone. The EGB, obtained when electrolysis of p-benzoquinone, or 1,4-naphthoquinone, is carried out at the reduction potential of their first voltammetric peak, conducted to electrogenerated phenacyl carbenes after halide evolution on the first obtained bromo-enolates. The stereoselectivity of the [2 + 2]cycloaddition of the carbene to the quinoid substrate is highly dependent on the electrode nature. Reaction mechanism proposal is discussed.

Novel mesoionic compounds derived from 3,7-diaryl-2H-imidazo[2,1-b][1,3,4]oxadiazines

Abstract Reversible reaction in which imidazo-oxadiazines are converted into mesoionic compounds, takes place under conditions of the sunlight and heating.