Electrochemical methoxylation of anethole on a graphite anode

A procedure is suggested for electrochemical methoxylation of anethole in an electrolyzer with a graphite cathode and potassium p-toluenesulfonate in methanol as supporting electrolyte; a mixture of two products is formed in the process.     

Electrolytic methoxylation of halognofurans

-Halogenofurans are electrolytically methoxylated in two ways in the presence of sulfuric acid electrolyte, methoxyl groups either adding at the 2 and 5 positions in the furan ring or replacing a ring halogen atom. The following are methoxylated: 2-bromo-, 2-iodofuran, 5-chloro-, 5-bromo-, and 5-iodofurfural, ethyl 5-bromopyromucate. Derivatives of 2, 2, 5-trimethoxy-2, 5-dihydrofuran are prepared, giving on hydrolysis-aldehydo- and-ketoacrylic acids.Total anode polarization graphs are obtained in order to study the electrolytic methoxylation reaction mechanism.Furfural and 2-acetylfuran methoxylate, but only after first undergoing conversion to the dimethylacetal [1, 2].Electrolytic methoxylation of furan derivatives using sulfuric acid as electrolyte was first applied to methoxylation of a pyromucic ester, which, as referred to above, is not methylated using ammonium bromide.     

The electrochemical methoxylation of methoxybenzenes and related compounds : The mechanism of electrochemical methoxylation of 1,4-dimethoxybenzene

Anodic oxidation of benzenoid aromatic ethers in methanolic KOH soln at a platinum electrode constitutes a one step method for the synthesis of the rare class of compounds, herein designated as the quinone diketals. The mechanism of conversion of 1,4-dimethoxybenzene to the diketal of p-benzoquinone, based on the evidence accumulated, is considered to proceed via discharge of the adsorbed aromatic compound, followed by nucleophilic reaction of the solvent system with the electrogenerated cationic species. The quinone diketal products resulting from anisole, 1,4-, 1,2-, and 1,3-dimethoxybenzene, 9,10-dimethoxyanthracene and benzodioxane have been established. In contrast methyl benzoate, anisonitrite, and benzene were found to be unreactive in agreement with a direct discharge scheme which does not involve methoxy radicals.     

Anodic methoxylation and acetoxylation of imines and imidates

Anodic oxidation of cyclic imidates, 2-aryl-2-oxazolines, in methanol provided the corresponding 4-methoxylated products. Anodic α-methoxylation and α-acetoxylation of open-chain imines derived from glycine esters and benzophenone were also achieved using a bromide ion mediator. On the other hand, anodic α-acetoxylation of CF₃-containing imine and imidate was successful without use of the bromine mediator. This is the first example of successful anodic α-substitution of imines and imidates.     

An unusual anodic methoxylation: 3,4-dimethoxyacetophenone

The electrolysis of 3,4-dimethoxyacetophenone in methanol at a platinum anode gives a high yield of 1-acetyl-4,5,5,6-tetramethoxycyclohexa-1,3-diene, whose structure is proven by ¹H and ¹³C NMR.     

Highly stereoselective methoxylation at the seven position of cephalosporins

Addition reaction of methanol to 7-methylsulfeniminocephem 1 β-oxide derivatives (6 and 12) under acidic conditions gave exclusively 7β-amino-7α-methoxycephem 1 β-oxides (7) stabilized by the formation of an intramolecular hydrogen bond between the 7β-amino and the oxygen atom at the 1-position.     

Deprotonation in anodic methoxylation of fluoroethyl phenyl sulfides using site-isolated heterogeneous bases

On the basis of the concept of site isolation in electrochemical reactions, we have successfully demonstrated acceleration of the deprotonation step in anodic methoxylation of fluoroethyl phenyl sulfides using silica gel supported bases.     

Total synthesis of khellinone and khellin the pyrogallol route regiospecific methoxylation of a benzofuran

Khellinone is prepared in 5 steps from the readily available triacetoxybenzofuran 7. The key step in the synthesis is a regiospecific oxidative methoxylation of benzofuran 9.     

A ceramic electrochemical microreactor for the methoxylation of methyl-2-furoate with direct mass spectrometry coupling

A ceramic electrochemical reactor (CEM) devoted to electrosyntheses was developed. The CEM was constituted by the assembly of five structured ceramic layers. On one layer, platinum interdigitated band electrodes with a submillimetre interelectrode gap were screen-printed. The microreactor chamber was constituted by seven channels and its volume was less than 100 microL. After a sintering step at 850 degree C for 1 h, the CEM appeared as a solid and compact unit. The CEM was directly connected to the six port valve of a mass spectrometer allowing an on-line sampling and analysis of the reaction mixture. The methoxylation of the methyl-2-furoate was carried out and the effect of the residence time in the CEM was investigated thanks to mass spectrometry analyses.     

Electrolytic methoxylation of 3,4-bis(hydroxymethyl) furan and synthesis of 4,5-bis-(hydroxymethyl) pyridazine

3,4-Bis(hydroxymethyl)furan was electrolytically methoxylated during intense cooling. 4,5-Bis(hydroxymethyl)pyridazine was obtained by reaction of the methoxylation product — 2,5-dimethoxy-3,4-bis (hydroxymethyl)-2,5-dihydrofuran — with hydrazine hydrate.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1306–1307, October, 1970.     

Electrolytic transformation of functional groups of fluoroorganic compounds. I. Anodic methoxylation and acetoxylation of trifluoroethyl sulfide

Anodic methoxylation and acetoxylation of phenyl trifluoroethyl sulfide were successfully performed to give the corresponding α-methoxy and α-acetoxy sulfides in good to excellent yields, respectively. These products were found to be useful building blocks for the synthesis of fluoroorganic compounds.     

Regioselective ortho-acetoxylation/methoxylation of N-(2-benzoylphenyl)benzamides via substrate directed C-H activation

A highly regioselective ortho-acetoxylation of N-(2-benzoylphenyl)benzamides has been achieved using a catalytic amount of Pd(OAc)₂ (10 mol %) and a stoichiometric amount of PhI(OAc)₂ in a mixture of acetic anhydride and acetic acid via C-H activation to produce the corresponding 2-acetoxybenzamides in good yields. ortho-Methoxylation has been accomplished using methanol under similar conditions.     

Une nouvelle methoxylation d'hydroperoxy-3 indolines issues de la photo-oxygenation d'indoles en milieu reducteur

3-Hydroperoxy-1,3,6-trimethyl-2-phenyl indolines coming from the sensitized photooxygenation of the indoles in presence of KBH₄ rearrange partially in basic methanol into the corresponding 3-hydroxy-6-methoxymethyL indolines.     

Studies on methoxylation in the 7H-naphtho[1,2,3-I,j][2,7]naphthyridin-7-one system

Studies on methoxylation in the 7H-naphtho[1,2,3-i,j][2,7]naphthyridin-7-one (sampangine) system represented by 3-bromo- and 4-bromosampangine as well as sampangine itself are described. We have found that regioselectivity of nucleophilic substitution in the sampangine system can be directed by reaction conditions. Under kinetic control (lower temperatures) substitution at C-4 is the predominant reaction, regardless of whether 3-bromo or 4-bromosampangine were used. At higher temperatures, when the reaction is thermodynamically controlled, substitution of the bromine atom at C-3 predominates. This is the first reported example of nucleophilic substitution in ring A of the 7H-naphtho[1,2,3-i,j][2,7]naphthyridin-7-one system.     

Electrochemical Fluoro-Chalcogenation

Electrochemical fluoro-chalcogenation (S, Se) of alkenes and alkynes, and recycle use of in situ generated PhSeF for allylic fluorination are discussed.     

Electrochemical immunoassays

Immunoassays (IA) use the specific antigen antibody complexation for analytical purposes. Radioimmunoassays (RIA), fluorescence immunoassays (FIA) and enzyme immunoassays (EIA) are well established in clinical diagnostics. For the development of hand-held devices which can be used for point of care measurements, electrochemical immunoassays are promising alternatives to existing immunochemical tests. Moreover, for opaque or optically dense matrices electrochemical methods are superior. Potentiometric, capacitive and amperometric transducers have been applied for direct and indirect electrochemical immunoassays. However, due to their fast detection, broad linear range and low detection limit, amperometric transducers are preferred. Competitive and non-competitive amperometric immunoassays have been developed with redox compounds or enzymes as labels. This review will give an overview of the most frequently applied principles in electrochemical immunoassays. The potential of an indirect competitive amperometric immunoassay for the determination of creatinine within nanomolar range and the circumvention of the most serious problem in electrochemical immunoassays, namely regeneration, will be discussed.