Oxidative coupling Ferric chloride

PHENOLIC OXIDATIVE COUPLING Ferric chloride. Silver carbonate. Vanadium oxytrichloride. Vanadium tetrachloride. 

OXIDATIVE COUPLING Cuprous chloride. Ferric chloride-Dimethylformamide. Manganese dioxide. Palladium(ll) chloride. Potassium ferricyanide. Silver carbonate-Celite. Thallium(Ill) trifluoroacetate. 

OXIDATIVE PHENOL COUPLING Ferric chloride-Silica. 

There are many reports on the biogenetic synthesis of these alkaloids by phenol oxidation. These reactions were carried out using a diphenolic isoquinoline with one-electron oxidizing reagents ferric chloride, potassium ferricyanide, manganese dioxide, and so on. In order to obtain the androcymbine-type compound 82 the diphenolic isoquinoline 81 was subjected to phenol oxidation with potassium ferricyanide (3a) and with ferric chloride (2b), respectively, but instead the homo-aporphine 83 (2a) coupled at the ortho-ortho position to the hydroxy groups. 

Oxidative coupling of aromatic compounds via the SchoU reaction has been appHed successhiUy to synthesise a polyarylethersulfone (18). High molecular weight polymer was obtained upon treating 4,4 -di(l-naphthoxy)diphenylsulfone and 4,4 -di(l-naphthoxy)ben2ophenone with ferric chloride. Equimolar amounts of the Lewis acid are required and the method is limited to naphthoxy-based monomers and other systems that can undergo the SchoU reaction. 

Oxidative coupling of phenols and phenol ethers.2 This reaction can be conducted with ferric chloride supported on silica gel. 

The norbelladin derivative (186) undergoes oxidative coupling in ferric chloride solution, the product (187) suffering further coupling on hydrolysis to give the crinin derivative (188).207 That these... 

Paquette has reported an intramolecular oxidative coupling using ferric chloride to prepare the intermediate 30 for the synthesis of cerorubenic acid-III. Addition of the dienolate of 28 to FeCls in dmf at —78°C produced the cyclopropane intermediate 29 in 54% yield (equation 16). Although the mechanism of this oxidative cyclization is not discussed in the paper, it is likely that a one-electron transfer pathway is involved. Copper(n) salts have also been utilized for intramolecular enolate coupling, but they proved to be somewhat less effective in the present context. 

Now let me come back to primary substitutions at the ferrocene nucleus. Together with Vil chevskaya, we phosphorylated ferrocene and its derivatives to triferrocenylphosphine oxides [263, 264). An unusual reaction, discovered in collaboration with Perevalova and Yur eva, was the direct cyanation of ferrocene with hydrocyanic acid in the presence of ferric chloride [265,272). Initially, cyanide attacks the iron atom of the ferricinium cation, then the cyanide group transfers to the ring while the iron is simultaneously reduced. The reaction was termed by us as the ricochet (from the metal to the nucleus) substitution it may be applied to many substituted ferrocenes and to the ruthenocenium cation [273), and it is now the simplest route to ferrocene carboxylic acids through their nitriles. Further, ferrocene was studied in acid-medium reactions with oxo compounds. With aldehydes [274), the reaction was complicated by the transformation of ferro-cenylalkyl carbinol formed Initially via the carbonium ion, followed by transformation to a radical which, in its turn, was coupled to 1,2-bis-(ferrocenylalkyl)ethane (27.5). The reaction with acetone led to 2,2-di-ferrocenylpropane (276). 

Esters of carboxylic acids undergo oxidative coupling in the a positions with respect to ester groups when treated in the enolate form with ferric chloride. Thus ethyl acetate stirred with lithium diisopropylamide in tet-rahydrofuran at -78 °C for 10 min and subsequently with anhydrous ferric chloride in dimethylformamide yields 69% of diethyl succinate [911]. 

Gentle oxidation of mercaptans and thiols leads to coupled products— disulfides. The oxidants used for this purpose are air [9], hydrogen peroxide [186], dichromates [663], chlorochromates [619], manganese dioxide [816], copper permanganate [896], ferric chloride [907], and diethyl azodicar-boxylate [977] (equations 544-546). 

Commercial reagent grade 2,2 d1hydroxy-l,l -b1naphthy1 from Aldrich Chemical Company, Inc. (l,l -b1-2-naphtho1) was used as obtained. It also can be prepared by the oxidative coupling of g-naphthol with ferric chloride and used after recrystalllzatlon from ethanol and then benzene. 

Since the mid-1950s, phenol oxidative coupling (7) has been actively applied to the synthesis of many types of alkaloids, with considerable progress being achieved especially in the field of isoquinoline alkaloids (8-H). As to aporphine synthesis, employment of new reagents such as vanadium oxyfluoride (12) greatly improved yields as compared to classical methods such as oxidation with potassium ferricyanide and ferric chloride. 

The oxidative demethylation of methyl ethers by ferric chloride is probabl limited to cases where a concomitant coupling reaction occurs as in the given example. 

Phenolic oxidative coupling. Oxidation of the phenolic amine (1) with 4.1 molar equivalents of ferric chloride hexahydrate gives 5-hydroxy-6-methoxyindole (2) in 10.6% yield. The amino nitrogen can also be substituted by an alkyl group.1... 

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