Carboxylic acids methoxylation

CjHgONa, which is obtained from ricinine by replacement of the methoxyl group by hydroxyl, chlorine and hydrogen in succession. Ricinidine, on hydrolysis, yields first an amide, C7Hg02N, and then a carboxylic acid, by ... 

Karrer and Schmid have examined the water-soluble constituents in poppy straw after extraction of the alkaloids, and have recorded the presence of -hydroxybenzaldehyde, vanillin, -hydroxystyrene, meconin and the following acids fumaric, dZ-lactic, benzoic, -hydroxycinnamic, p-hydroxybenzoic, 2-hydroxycinchoninic, vanillic, phthalic, hemipinic and m-hemipinic, with a more highly unsaturated, carboxylic acid J, b.p. 170-570-02 mm., and three unidentified substances Fa , m.p. 271-2° Wx, m.p. 310° (dec.) and Q, m.p. 260° the two latter are free from nitrogen and contain no methoxyl. 

Carboxylic acids can be converted to symmetrical ketones by pyrolysis in the presence of thorium oxide. In a mixed reaction, formic acid and another acid heated over thorium oxide give aldehydes. Mixed alkyl aryl ketones have been prepared by heating mixtures of ferrous salts.1717 When the R group is large, the methyl ester rather than the acid can be decarb-methoxylated over thorium oxide to give the symmetrical ketone. 

Intermolecular Markovnikov-type addition of phenols (ArOH), carboxylic acids (RCO2H), and protected amines (TsNH2) to alkenes, such as 4-MeOC6H4CH2CH= CH2, can be catalysed by triflic acid in low concentrations (1-5%). Functional groups, such as the methoxyl on aromatics, can be tolerated if the concentration of triflic acid and the reaction temperature are controlled appropriately. This reaction provides one of the simplest alkene addition methods and can serve as an alternative to metal-catalysed reactions.33... 

Electrolysis of A-carbamoylaspartic acid or A-ethoxycarbamoylaspargine in MeOH-MeONa-(C) affords the corresponding methoxylated products [140], A 5-fluorouracil derivative (LXIII), a potent antitumor agent, can be prepared via electrolytic methoxylation of A-acylazacycloalkane-2-carboxylic acids (LXI) in MeOH-MeONa-(C) and subsequent condensation of (LXII) with 2,4-bis-(trimethylsilyl)-5-fluorouracil (TMS-5-FU) [Eq. (31)] [133,141]. Recently, the decarboxylative methoxylation of o -amino acids has been extended to prepare useful chiral building blocks [127-130]. 

A. Olefinic compounds Acetylenic compounds Aromatic compounds Carbonyl compounds F/c-Oxygen compounds Nitrogen compounds Sulfur compounds Halogen compounds Other heteroatom compounds Organometallic compounds Stereoselective and Stereospecific Electrooxidation A. Carboxylic acids Acetoxylation Methoxylation Acetamidation... 

Utley and Yates [276] reported an interesting stereochemistry and regiochemistry of methoxylated prdoucts derived from 4-phenylcyclohexene-2-carboxylic acid ... 

Stereoisomeric (exo and endo) bicycloalkane carboxylic acids are stereospecifically methoxylated, hydroxylated, and amidated [277,278]. cyclic monocarboxylic acids are also anodically decarboxylated to give stereoselectively cycloalkenes in high yields [279,280]. 

Carboxylic acids with a chiral center at the a-carbon give racemic Kolbe dimers [399,400]. Addition products of radicals derived from such carboxylic acids to olefins are also racemic [401]. Racemization is also observed in anodic methoxylation of carboxylic acids [402], These facts may suggest that Kolbe rdicals interact so weakly with the anode surface that their configuration cannot be stabilized during the reaction. However, it can also be stated that the radicals interact sterically with the anode so that the geometry of the dimers is influenced by the anode material (see Sec. IV). 

Work continues on the factors which can affect the photo-methoxylation of esters of pyridine carboxylic acids in acidic methanol solutions and a remarkable effect of atmosphere has been reported.Under oxygen, methoxylation of, for example, (134) occurs at both the a- and 3-positions in a respective ratio of 3 5 but in nitrogen degassed solutions, substitution occurs specific-... 

Jaaskelelainen and Poppius-Levlin [92] found that the molecular weight, methoxyl content and phenolic hydroxyl content of residual lignin in pulps treated with neutral peracetic acid was unchanged, while the carbonyl and carboxylic acid contents increased. 

The anodic oxidation of carboxylic acids has also been carried out using a solid-supported base in methanol. Non-Kolbe-type electrolysis takes place to give the corresponding methoxylated product (Equation 12.7). The acid-base reaction between a carboxylic acid and a solid-supported base seems to reduce the cell voltage and makes the electrochemical reaction possible. Kolbe-type carbon-carbon coupling using aliphatic and benzylic carboxylic acids has also been accomplished using this method [26]. Based on a similar concept, anodic fluorination by an alkali metal... 

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