Synthesis electrochemical oxidation

Synthesis depends on gas-phase pyrolysis techniques , and interconversion is by electrochemical oxidation . Understanding of the mechanisms by which the boranes interconvert and build up into larger clusters is growing . 

Continuing his studies on the metallation of tetrahydro-2-benzazepine formamidines, Meyers has now shown that the previously unsuccessful deprotonation of 1-alkyl derivatives can be achieved with sec-butyllithium at -40 °C <96H(42)475>. In this way 1,1-dialkylated derivatives are now accessible. The preparation of 3//-benzazepines by chemical oxidation of 2,5- and 2,3-dihydro-l/f-l-benzazepines has been reported <96T4423>. 3Af-Diazepines are also formed by rearrangement of the 5//-tautomers which had been previously reported to be the products of electrochemical oxidation of 2,5-dihydro-lAf-l-benzazepine <95T9611>. The synthesis and radical trapping activities of a number of benzazepine derived nitrones have been reported <96T6519, 96JBC3097>. 

Electrochemical Oxidations of Arylmethanes Investigated in Micro Reactors Organic synthesis 85 [OS 85] Oxidation of4-methoxy toluene to 4-methoxy benzaldehyde... 

The Clauson-Kaas pyrrole synthesis was adapted to a soluble polyglycerol (PG) support <060L403>. Electrochemical oxidation of furan 33 in the presence of methanol followed by hydrogenation gave 2,5-dimethoxytetrahydrofuran 34. Cyclocondensation with primary arylamines gave A-arylpyrroles 35. Removal from the PG support was then accomplished by treatment of 35 with LiOH which gave 2-pyrrolepropanoic acids 36. 

Denti, G., Campagna, S., Serroni, S., Ciano, N., and Balzani, V. (1992) Decanuclear homo- and hetero-metallic polypyridine complexes Synthesis, absorption spectra, luminescence, electrochemical oxidation, and intercomponent energy transfer./. Am. Chem. Soc. 114, 2944-2950. 

Alder (hDA) reaction <00CEJ3755> and the electrochemical oxidation of m-hydroxyalkyl tetrahydropyrans offers a different approach to spiroketals <00TL4383>. The synthesis and stereochemistry of insect derived spiroacetals has been reviewed <00S1956>. 

In this article we report the synthesis and electrochemical properties of the polymer derived from oxidation of X, poly(I), and the characteristics of a microelectrochemical transistor based on the polymer. Poly(I), which is formed by electrochemical oxidation of X, Equation 1, consists of a conducting polymer backbone, polythiophene. 

Studies on the electrochemical oxidation of silyl-substituted ethers have uncovered a rich variety of synthetic application in recent years. Since acetals, the products of the anodic oxidation in the presence of alcohols, are readily hydrolyzed to carbonyl compounds, silyl-substituted ethers can be utilized as efficient precursors of carbonyl compounds. If we consider the synthetic application of the electrooxidation of silyl-substituted ethers, the first question which must be solved is how we synthesize ethers having a silyl group at the carbon adjacent to the oxygen. We can consider either the formation of the C-C bond (Scheme 15a) or the formation of the C-O bond (Scheme 15b). The formation of the C Si bond is also effective, but this method does not seem to be useful from a view point of organic synthesis because the required starting materials are carbonyl compounds. 

The potentiality of the present methodology is demonstrated by the synthesis of y-undecalactone, as shown in Scheme 18 [37,47], The treatment of the THP-protected cu-hydroxyalkyl iodide with the anion of methoxybis(trimethylsilyl) methane gave the corresponding alkylation product. Acidic deprotection of the hydroxyl group followed by Swern oxidation produced the aldehyde. The aldehyde was allowed to react with heptylmagnesium bromide, and the resulting alcohol was protected as tm-butyldimethylsilyl ether. The electrochemical oxidation in methanol followed by the treatment with fluoride ion afforded the y-undeealactone. 

Nitrogen compounds are also effective as nucleophiles in the anodic oxidation of silyl-substituted ethers. The electrochemical oxidation in the presence of a carbamate or a sulfonamide in dry THF or dichloromethane results in the selective cleavage of the C-Si bond and the introduction of the nitrogen nucleophile at the carbon (Scheme 21) [55]. Since a-methoxycarbamates are useful intermediates in the synthesis of nitrogen-containing compounds [44], this reaction provides useful access to such compounds. Cyclic silyl-substkuted ethers such as 2-silyltetrahydrofurans are also effective for the introduction of nitrogen nucleophiles. The anodic oxidation in the presence of a carbamate or a... 

Other mediators which have been used in combination with diaphorase for the regeneration of NAD+ are riboflavin and Vitamin K3, which is 2,3-dimethyl-1,4-naphthoquinone. However, especially riboflavin is not stable enough for synthetic applications [40]. Better stability is exhibited by phenanthrolindiones as mediators. In combination with diaphorase, Ohshiro [41] showed the indirect electrochemical oxidation of cyclohexanol to cyclohexanone using the NAD+ dependent HLADH with a turnover frequency of two per hour. For an effective enzymatic synthesis, this turnover frequency, however, would be too small. In our own studies, we were able to accelerate the NAD(P)+ regeneration considerably by lowering the electron density within the... 

Direct production of benzoquinone (BQ) from benzene is one of the targets in industrial chemistry. Considerable efforts have been made to develop the electrochemical oxidation of benzene to p-benzoquinone to the industrial scale thus forming a basis for a new hydroquinone process [40]. Benzene in aqueous emulsions containing sulfuric acid (1 1 mixture of benzene and 10% aqueous H2S04) forms, at the anode, p-benzoquinone which can be reduced cathodically to yield hydroquinone in a paired synthesis. A divided cell with Pb02 anodes is used. 

The direct electrochemical oxidation of aliphatic alcohols (1) to carbonyl compounds (2) (Eq. 1) is not a convenient way for synthesis because of the high oxidation potentials of alcohols. The oxidation always competes with the oxidation of a solvent and supporting electrolyte, leading to low current efhdencies and side products. 

Another useful route to alkaloids involves the electrochemical oxidation of lactams (145) bearing functionality on nitrogen that can be used to intramolec-ularly capture an intermediate acyl im-minium ion (146). The concept is portrayed in Scheme 33 and is highlighted by the synthesis of alkaloids lupinine (150) and epilupinine (151) shown in Scheme 34 [60]. Thus, the electrooxidation of lactam (147) provided a 71% yield of ether (148). Subsequent treatment with titanium tetrachloride affected cyclization and afforded the [4.4.0] bicyclic adduct (149). Krapcho decarbomethoxylation followed by hydride reduction of both the... 

A convenient method to affect the oxidation p- to nitrogen in piperidines is based on the anodic oxidation of N-carboalkoxy piperidines (Scheme 35). The electrochemical oxidation of piperidine (152) in the presence of acetic acid and potassium acetate, for example, afforded a mixture of isomeric 2-hydroxy-3-acetoxypiperidines (153) in a combined yield of 93%, following an aqueous workup [61]. Reduction with sodium boro-hydride severed the C-OH bond. Treatment with acid and then base completed a synthesis of pseudoconhydrine (154). 

It is quite often possible to prepare hydroxypyridinone complexes directly by one-pot synthesis from the appropriate hydroxypyranone, amine, and metal salt 90-92). They can also be prepared by reacting complexes such as P-diketonates with hydroxypyridinones (see e.g., Ce, Mo later). Several maltolate complexes, of stoichiometry ML2, ML3, ML4, or MOL2, have been prepared by electrochemical oxidation of the appropriate metal anode, M — a first-row d-block metal (Ti, V, Cr, Mn, Fe, Co, Ni), In, Zr, or Hf, in a solution of maltol in organic solvent mixtures 92). Preparations of, e.g., manganese(III), vanadium(III), or vanadium(V) complexes generally involve oxidation... 

In the synthesis of compounds of the same kind as 161 but with only one substituent at the 3-position, the reaction conditions caused the electrochemical oxidation of the dihydrooxazines to give a 2/7-oxazine <2004JOC882>. The reaction will be discussed with the syntheses of conjugated 1,4-oxazines in Section 8.06.9.3 (Scheme 34). 

The direct electrochemical synthesis (Scheme 2) of the addncts of organomagnesinm halides with 2,2 -bipyridine (6) and salts of organodihalogenomagnesinm(II) anions (7) was reported by Hayes and coworkers . Adducts of different stoichiometry and 7 were obtained in the electrochemical oxidation of magnesium in ACN solutions containing organic halides RX (8), a.ro-dihalides XR X (9) and 8 with ammonium salts R NX, respectively. All new products showed none of the typical reactions of Grignard reagents. 

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