Andrés Zapata

Electrochemical reduction of diaryl-1,2-diketones in the presence of carbonimidoyl dichlorides. A new method for the synthesis of enediol iminocarbonates

Abstract Selective cathodic reduction of diaryl-1,2-diketones in the presence of carbonimidoyl dichlorides provides a new and very convenient method for the synthesis of the title compounds.

Electrochemical reduction of carbonimidoyl dichlorides. A new method for the preparation of isocyanides

Abstract The cathodic reduction of carbonimidoyl dichlorides provides a new, mild and free-reagent method for the preparation of isocyanides in almost quantitative yields.

ELECTROCHEMICAL SYNTHESIS AND X-RAY MOLECULAR STRUCTURE OF 2-ARYLIMINO-4,5-DIARYL-1,3-DIOXOLES

Abstract Selective cathodic reduction of diaryl-1,2-diketones in the presence of N-arylcarbonimidoyl dichlorides leads to 2-arylimino-4,5-diaryl-1,3-dioxoles, a little known class of heterocycle, in almost quantitative yields. NMR spectra of these compounds show a remarkable dependence upon temperature associated with a low configurational stability around the carbon-nitrogen double bond. An x-ray crystallographic analysis has been performed, showing an unusually short carbon-nitrogen double bond, which might be expected to be longer to explain the mechanism of the facile thermal isomerization through a polar transition state in which the double bond character is lost.

ELECTROCHEMICAL SYNTHESIS AND X-RAY MOLECULAR STRUCTURE OF 3,4,5-TRIARYL-2-ARYLIMINOOXAZOLINES

Abstract Selective cathodic reduction of benzilmonoimines in aprotic medium at a mercury pool cathode, under constant potential, in the presence of equimolecular amounts of N-arylcarbonimidoyl dichlorides, provides a new and very convenient method for the synthesis of 3,4,5-triaryl-2-aryliminooxazolines. Geometrical characteristics of this little known class of heterocycle were determined by X-ray crystallography of 2-(4-chlorophenylimino)-5-(4-methoxyphenyl)-3-(4-methylphe-nyl)-4-phenyloxazoline.

Electrochemical generation of alkyl and aryl isocyanides

Abstract An efficient and widely applicable reagent-free method for the synthesis of alkyl and aryl isocyanides has been established. The electrochemical reduction of alkyl and aryl carbonimidoyl dichlorides under constant cathode potential leads to the corresponding isocyanides in almost quantitative yields. The availability of the starting materials, the mildness of the reaction conditions as well as the easy isolation of products are noteworthy, advantageous features of the procedure.

Synthesis and X-ray molecular structure of N-(1-amino-2,2-dichloroethyl)benzamides

Abstract Efficient procedures for the synthesis of N-(1-alkylamino-2,2-dichloroethyl)benzamides, N-(1-arylamino-2,2-dichloroethyl)benzamides and N-(1-amino-2,2-dichloroethyl)benzamides are reported. These compounds are of special interest as intermediates to access new heterocyclic series. N-(2,2-dichlorovinyl)amides react with primary or secondary alkylamines to yield the title compounds in high to quantitative yields. However, similar addition reactions with arylamines or ammonia are unsuccessful. In these cases the synthesis of the targeted products may be achieved by starting from N-(1,2,2,2-tetrachloroethyl)benzamides which are aminated via nucleophilic substitution yielding the corresponding N-(1-amino-2,2,2-trichloroethyl)benzamides. Finally, these compounds are selectively monodechlorinated by electrochemical reduction at constant cathodic potential. The crystallographic X-ray structure of N-(2,2-dichloro-1-isopentylaminoethyl)-4-methylbenzamide has been determined.

THE REACTION OF PHTHALIDYLIDENE DICHLORIDE WITH PRIMARY AMINES. SYNTHESIS AND X-RAY MOLECULAR STRUCTURE OF N-SUBSTITUTED PHTHALISOIMIDES

Abstract An efficient method for the synthesis of N-substituted phthalisoimides, by reaction of phthalidylidene dichloride with primary amines, is described. The reactions with arylamines, arylenediamines and alkylenediamines lead to the corresponding phthalisoimides or bisphthalisoimides in nearly quantitative yields. However, the reactions with alkylamines are not useful because of the relatively high nucleophilicity of alkylamines. Certain particular behaviours of arylamines, associated with the presence of specific ortho-substituents have been found. The reactions of arylamines bearing an o-hydroxymethyl group provide a convenient method for preparing 2-benzoxazinylbenzoic acids. The X-ray crystallographic structures of N-(2-methoxyphenyl)phthalisoimide 3a and 2-(4H-3,1-benzoxazin-2-yl)benzoic acid 15a have been determined.

Electrochemical reduction of diheteroaryl-1,2-diketones in the presence of carbonimidoyl dichlorides. First synthesis of 2-arylimino-4,5-di-2-furyl-1,3-dioxoles and (E)-1,2-di-2-furylvinylene bis(N-arylchloroformimidates)

Abstract Selective cathodic reductions of 2,2′-furil in an aprotic medium, under constant potential, in the presence of equimolecular amounts of N -arylcarbonimidoyl dichlorides provide previously unknown 2-arylimino-4,5-di-2-furyl-1,3-dioxoles in high yields. These compounds were formed accompanied by minor products which were identified as ( E )-1,2-di-2-furylvinylene bis( N -arylchloroformimidates), a new class of compound. Similar reductions were applied to 2,2′-pyridil, 2,2′-thenil and bis(pyrrol-2-yl)-1,2-ethanedione. However, arylisocyanides were quantitatively generated by mediated electroreduction of arylcarbonimidoyl dichlorides.

A NEW METHOD FOR THE SYNTHESIS OF N-ARYLPHTHALISOIMIDES

Abstract N-arylphthalisoimides have been synthesized in almost quantitative yields by the reaction, under very mild conditions, of 3,3-dichlorphthalide with aromatic amines.

Electrolytic preparation of 2-osuloses: a route to L-ascorbic acid

ConclusionsIndirect electrosynthesis of 2-osuloses from aldopentoses and ketohexoses has shown to be an interesting tool for reducing the amount of chemical oxidant (copper (II) involved in the reaction. However, the experimental conditions under which the reaction is carried out are far from those industrially acceptable. Nevertheless, the potential advantages of the electrolytic method, as well as its interest in organic synthesis, are so important that further effort should be spent in studying this procedure.