Alcohols oxidative carbonylation

As a unique reaction of Pd(II), the oxidative carbonylation of alkenes is possible with Pd(ll) salts. Oxidative carbonylation is mechanistically different from the hydrocarboxylation of alkenes catalyzed by Pd(0), which is treated in Chapter 4, Section 7.1. The oxidative carbonylation in alcohol can be understood in the following way. The reaction starts by the formation of the alkoxy-carbonylpalladium 218. Carbopalladation of alkene (alkene insertion) with 218 gives 219. Then elimination of /3-hydrogen of this intermediate 219 proceeds to... 

The first report of oxidative carbonylation is the reaction of alkenes with CO in benzene in the presence of PdCh to afford the /3-chloroacyl chloride 224[12,206]. The oxidative carbonylation of alkene in alcohol gives the q, f3-unsaturated ester 225 and /3-alkoxy ester 226 by monocarbonylation, and succinate 111 by dicarbonylation depending on the reaction conditions[207-209]. The scope of the reaction has been studied[210]. Succinate formation takes... 

Aconitatc was obtained as a minor product in the carbonylation of propar-gyl alcohol[479]. However, in the two-step synthesis of methyl aconitate (536) from propargyl alcohol in 70% overall yield, the first step is the oxidative carbonylation under CO and air using Pdli and KI to giNe dimethyl hydro-xymethylbutenedioate (535), which is carbonylated further to give trimethyl aconitate (536) by u.sc of [Pd(Tu)4jl2 as a catalyst[480]. 

As an application of maleate formation, the carbonylation of silylated 3-butyn-l-ol affords the 7-butyrolactone 539[482], Oxidative carbonylation is possible via mercuration of alkynes and subsequent Lransmetallation with Pd(II) under a CO atmosphere. For example, chloromercuration of propargyl alcohol and treatment with PdCF (1 equiv.) under 1 atm of CO in THF produced the /3-chlorobutenolide 540 in 96% yield[483]. Dimethyl phenylinale-ate is obtained by the reaction of phenylacetylene, CO, PdCU, and HgCl2 in MeOH[484,485]. 

Oxidative carbonylation of alcohols with PdCh affords the carbonate 572 and oxalate 573(512-514]. The selectivity of the mono- and dicarbonylation depends on the CO pressure and reaction conditions. In order to make the reaction catalytic, Cu(II) and Fe(III) salts are used. Under these conditions, water is formed and orthoformate is added in order to trap the water. Di-/-butyl peroxide is also used for catalytic oxidative carbonylation to give carbonates and oxalates in the presence of 2,6-dimetliylpyridine(515]. 

Carbamates are produced by the oxidative carbonylation of amines in alcohol, and active research on the commercial production of carbamates as a precursor of isoyanates based on this reaction has been carried out. As an example, ethyl phenylcarbamate (582) is produced in a high yield (95%) with... 

Many biological processes involve oxidation of alcohols to carbonyl compounds or the reverse process reduction of carbonyl compounds to alcohols Ethanol for example is metabolized m the liver to acetaldehyde Such processes are catalyzed by enzymes the enzyme that catalyzes the oxidation of ethanol is called alcohol dehydrogenase... 

Oxidative Carbonylation of Ethylene—Elimination of Alcohol from p-Alkoxypropionates. Spectacular progress in the 1970s led to the rapid development of organotransition-metal chemistry, particularly to catalyze olefin reactions (93,94). A number of patents have been issued (28,95—97) for the oxidative carbonylation of ethylene to provide acryUc acid and esters. The procedure is based on the palladium catalyzed carbonylation of ethylene in the Hquid phase at temperatures of 50—200°C. Esters are formed when alcohols are included. Anhydrous conditions are desirable to minimize the formation of by-products including acetaldehyde and carbon dioxide (see Acetaldehyde). 

The elimination of alcohol from P-alkoxypropionates can also be carried out by passing the alkyl P-alkoxypropionate at 200—400°C over metal phosphates, sihcates, metal oxide catalysts (99), or base-treated zeoHtes (98). In addition to the route via oxidative carbonylation of ethylene, alkyl P-alkoxypropionates can be prepared by reaction of dialkoxy methane and ketene (100). 

In general, peroxomonosulfates have fewer uses in organic chemistry than peroxodisulfates. However, the triple salt is used for oxidizing ketones (qv) to dioxiranes (7) (71,72), which in turn are useful oxidants in organic chemistry. Acetone in water is oxidized by triple salt to dimethyldioxirane, which in turn oxidizes alkenes to epoxides, polycycHc aromatic hydrocarbons to oxides and diones, amines to nitro compounds, sulfides to sulfoxides, phosphines to phosphine oxides, and alkanes to alcohols or carbonyl compounds. 

In the alcohol oxidations, the sulfonium intermediate (2, nucleophile = R2C(OH)) loses a proton and dimethyl sulfide to give the carbonyl compound (42). The most common mechanism for the decomposition of (2) is attack by a mild base to remove a proton from one of the methyl groups. Subsequent cycHc coUapse leads to the carbonyl compound and dimethyl sulfide (eq. 9) ... 

Bromine or chlorine dissolved in hexamethylphosphoric triamide [680-31-9] (HMPT) with a base, eg, NaH2PO, present, oxidizes primary and secondary alcohols to carbonyl compounds in high yield (38). 

The oxidative carbonylation of styrene with carbon monoxide, oxygen, and an aUphatic alcohol in the presence of a palladium salt, a copper salt, and sodium propionate also provides the requisite cinnamate. 

Dimethyl sulfoxide reacts with trifluoroacetic anhydride at low tempera ture to give a complex that is an efficient reagent for the oxidation of alcohols to carbonyl compounds [40 41] This reagent can be used to oxidize primary and secondary aliphatic alcohols, cycloalkyl alcohols, and allylic, homoallylic, ben-zylic, acetylenic, and steroidal alcohols (equation 19)... 

Hydrogenation of carbonyls, or incipient carbonyls such as phenols (86), in lower alcohol solvents may result in the formation of ethers. The ether arises through formation of acetals or ketals with subsequent hydrogenolysis. The reaction has been made the basis of certain ether syntheses (45,97). Reaction of alcohols with carbonyls may be promoted by trace contamination, such as iron in platinum oxide (22,53), but it is also a property of the hydrogenation catalyst itself. So strong is the tendency of palladium-hydrogen to promote acetal formation that acetals may form even in basic media (61). 

The anion in KRu04 has a slightly flattened tetrahedral structure (Ru-O 1.73 A). Organic-soluble salts like Pr4NRu04 are selective mild oxidants that will oxidize alcohols to carbonyl compounds but will not affect double bonds [54a]. ESR indicates that Ru04 (g = 1.93 gy = 1.98 gz = 2.06) has a compressed tetrahedral geometry with the electron in dz2 [54b]. 

Dipyridiue-chromium(VI) oxide2 was introduced as an oxidant for the conversion of acid-sensitive alcohols to carbonyl compounds by Poos, Arth, Beyler, and Sarett.3 The complex, dispersed in pyridine, smoothly converts secondary alcohols to ketones, but oxidations of primary alcohols to aldehydes are capricious.4 In 1968, Collins, Hess, and Frank found that anhydrous dipyridine-chromium(VI) oxide is moderately soluble in chlorinated hydrocarbons and chose dichloro-methane as the solvent.5 By this modification, primary and secondary alcohols were oxidized to aldehydes and ketones in yields of 87-98%. Subsequently Dauben, Lorber, and Fullerton showed that dichloro-methane solutions of the complex are also useful for accomplishing allylic oxidations.6... 

Oxidation of alcohols to carbonyls (2° alcohols can be selectively oxidized)... 

Oxoreductases include enzymes such as dehydrogenases, oxidases and peroxidases which catalyse transformations such as oxidation of alcohols to carbonyls and dehydrogenation of functionalized alkanes to alkenes. 

The oxidation of alcohols to carbonyl compounds by permanganate proceeds most rapidly in basic solution and it is with this medium that the majority of kinetic studies have been performed. 

M-NHC catalysts in this area. Metal catalysed carbonylation also provides an alternative synthetic ronte to the prodnction of materials that traditionally reqnire highly toxic precnrsors, like phosgene. This section discnsses carbonylation of aryl hahdes, oxidative carbonylation of phenolic and amino componnds, carbonylation of aryl diazoninm ions, alcohol carbonylation, carbonylative amidation, and copolymerisation of ethylene and CO. 

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