Oxidative Carbonylation Reactions

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]. 

The alkylurea 576 and oxamide 577 are formed by oxidative carbonylation of amines under CO pressure using Pd/C as a catalyst[518]. The urea formation proceeds under atmospheric pressure using PdCh and CuCl2[519]. The mono-and double carbonylations of / -aminoethanol (578 and 579) afford the cyclic carbamate (oxazolidinones) 580 and oxamide (morpholinediones) 581 [520,521]. 

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 

As an e.xtension of the oxidative carbonylation with alkyl nitrites, malonate can be prepared by the oxidative carbonylation of ketene (583)[524], Also, the acetonedicarboxylate 585 is prepared by the Pd-catalyzed, alkyl nitrite-mediated oxidative carbonylation of diketene (584)[525], 

Although turnover of the catalyst is low, even unreactive cyclohexane[526] and its derivatives are oxidatively carbonylated to cyclohexanecarboxylic acid using KiS Og as a reoxidant in 565% yield based on Pd(II)[527]. Similarly, methane and propane are converted into acetic acid in 1520% yield based on Pd(II) and butyric acid in 5500% yield [528], 

In the last six chapters we discussed the transition metal catalyzed carbonylative activation of organohalogen (C-X, X = I, Br, Cl, OTf, etc.) compounds. They all have one common point in their reaction mechanism taking a palladium catalyst, for example, the reactions start with Pd(0) and then go to Pd(II) after an oxidative addition. To summarize, the reactions all go through Pd(0) to Pd(II) and a Pd(0) cycle. But for oxidative carbonylation reactions, the reactions go through Pd(ll) to Pd(0) and a Pd(II) cycle. Clearly, oxidative carbonylations need additional oxidants to reoxidize the Pd(0) to Pd(II), and various organic nucleophiles were applied as substrates in the presence of CO. One of the most obvious advantages for oxidative carbonylation reactions is the oxidative addition step can be avoid which is more reluctant under CO atmosphere. 

Beller and X.-F. Wu, Transition Metal Catalyzed Carbonylation Reactions, DOI 10.1007/978-3-642-39016-6 8, Springer-Veriag Berlin Heidelberg 2013 

As early as 1963, Tsuji and colleagues described the reaction of olefin-palladium chloride complexes with CO to produce jS-chloroacyl chlorides [1,2]. Both internal and terminal aliphatic olefins were transformed into the corresponding chloroesters when the reaction was conducted in alcohols. Later on, in 1969, Yukawa and Tsutsumi reported on the reaction of a styrene-palladium complex with CO in alcohols [3]. Here, various cinnamates and phenylsuccinates were synthesized. Compared with Tsuji s work, they proposed a different reaction mechanism. They assumed that the oxidative addition of the alkyloxycarbonyl groups into styrenes is the key step, but a stoichiometric amount of palladium was stiU necessary to perform the reaction. Another version of a dialkoxycarbonylation of olefins was reported by Heck [4], using mercuric chloride as additive. 

While these initial examples were performed in the presence of stoichiometric amounts of palladium, the first catalytic dialkoxycarbonylation of olefins was independently described by Fenton [5] and Medema [6] in 1969 and 1970. More specifically, a catalytic amount of palladium was used together with an equivalent of CuCL, and the reactions were run at high pressure of CO and comparatively high reaction temperatures (140-150 °C). Heck demonstrated that CuCL is not able to efficiently reoxidize Pd(0) at low temperatures [7-9]. In 1972 Fenton and Steinwand reported on the oxidative carbonylation of olefins to succinates [10]. For the reoxidation of palladium, iron and copper chlorides were used, but oxygen should also have been present—otherwise only low yields of succinates were obtained. A related study of the hydroxycarbonylation of olefins was described by the same group [11]. Nowadays, this type of reaction is efficiently performed in the presence of protic acids.  

In 1979 Cometti and Chiusoli published their results on the synthesis of methyl cinnamates from styrene [20]. Using a mixture of PdCU, CuCU, MgCl2 and 

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Abstract The basic principles of the oxidative carbonylation reaction together with its synthetic applications are reviewed. In the first section, an overview of oxidative carbonylation is presented, and the general mechanisms followed by different substrates (alkenes, dienes, allenes, alkynes, ketones, ketenes, aromatic hydrocarbons, aliphatic hydrocarbons, alcohols, phenols, amines) leading to a variety of carbonyl compounds are discussed. The second section is focused on processes catalyzed by Pdl2-based systems, and on their ability to promote different kind of oxidative carbonylations under mild conditions to afford important carbonyl derivatives with high selectivity and efficiency. In particular, the recent developments towards the one-step synthesis of new heterocyclic derivatives are described. 

A wide range of organic substrates can undergo an oxidative carbonylation reaction. Depending on reaction conditions, alkenes have been converted into -chloroalkanoyl chlorides (oxidative chloro-chlorocarbonylation) [1,2], succinic diesters (oxidative dialkoxycarbonylation) [3-20], a,/J-unsaturated esters [21,22] (oxidative monoalkoxycarbonylation), or /J-alkoxyalkanoic esters [11] (oxidative alkoxy-alkoxycarbonylation), according to Eqs. 10-13. 

Depending on the metal promoter and reaction conditions, alkynes may undergo several different oxidative carbonylation reactions, most of which are promoted by Pd(II) species and are usually carried out in the presence of an oxidizing agent (such as Q1CI2 or 02). 

The oxidative carbonylation reaction of enolizable ketones follows the general routes already illustrated for simple alkenes. Thus, a-methoxycarbonyl-ation may occur either by addition of a Cl - Pd - C02Me species to the enolic... 

The first oxidative carbonylation reactions (cf. Section 2.1.2.5) with methane used superacid catalysts to perform the carbonylation in a Koch-type reaction which involved protolytic oxidation of methane to the methyl cation (eq. (29) [137]) ... 

Carbonylations which are accompanied hy oxidation reactions, are frequently called oxidative carbonylations . Reactions of this type are usually carried out in the presence of a catalyst and an oxidant, for example air. In principle, similar starting materials to those in classical Reppe carbonylations may be used, but as a result of the additional oxidation step different reaction products are obtained. To some extent, this method represents an extension of the Reppe carbonylation. For... 

A major challenge in Pd-catalyzed oxidative carbonylation reactions is the decomposition of catalysts into inactive metallic Pd, promoted by the strong reducing CO reagent. Successful examples of Pd-catalyzed oxidative carbonylation typically... 

Recent developments in the synthesis of heterocyclic derivatives by Pdl2-catalyzed oxidative carbonylation reactions of suitably functionalized alkynes 03JOM(687)219. 

Above we mentioned the palladium-catalyzed carbonylative coupling of organohalides with C-H nucleophiles. Compared with their version of carbonylative coupling with organometaUic reagents, the pre-activation of C-H bonds was not needed. The other pathway in carbonylative C-H activation is the reaction between two nucleophiles in the presence of an additional oxidant sometimes these types of reactions are also called oxidative carbonylations. Only the reaction between Ar-H and nucleophiles will be discussed in the following the other oxidative carbonylation reactions will be summarized in Chap. 8. 

In the next chapter, oxidative carbonylation reactions will be summarized. 

For reviews on Pdl2-catalyzed oxidative carbonylation reactions, see [74—76]. 

In this chapter we discussed the transition metal catalyzed oxidative carbonylation of alkenes, alkynes and organometallic reagents. In these types of reactions, an additional oxidant is needed to reoxidize the catalyst back to an active state after a reductive elimination step. The oxidants applied are normally Cu(OAc)2 or BQ, air or O2, as more green oxidants should be investigated and applied in oxidative carbonylation reactions. In contrast, carbonylative reduction reactions using CO as a reductant are also interesting. In the next chapter, the reduction of C-NO2 with CO will be discussed. 

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