Benzaldehyde Baeyer-Villiger

Either in the solid state or when treated with Na carbonate, it is dissociated into benzaldehyde and H2Oz cold acetic anhydride converts it into acetic peroxide, acetic acid and benzaldehyde (Refs 1 2). On adding benzaldehyde to a dil ale soln of H,Oz and H2S04, Baeyer Villiger (Ref 3) obtd a product, O—CX... 

One of the achievements in Baeyer-Villiger oxidation is aerobic catalytic rearrangement of cyclic ketones, for example, / -butylcyclohexanone, in the presence of Ru02 or Mn02 (0.05 equiv) and benzaldehyde (3 equiv) at room temperature (Equation 32), giving the respective e-caprolactones in yields up to 95%, the reaction being accelerated in the presence of lithium perchlorate <1994SL1037>. 

Fig. 11.33. Regioselective Baeyer-Villiger rearrangement of an electron-poor aromatic aldehyde. This reaction is part of the autoxidation of benzaldehyde to benzoic acid. Both alternative reaction mechanisms are shown the [1,2]-rearrangement (top) and the /3-elimination (bottom).

Treatment of heterocyclic enamides with peracids resulted in the oxidative fission of the double bond, followed by Baeyer-Villiger reaction of the methoxylated benzaldehyde intermediate45 (Scheme 30). 

Oxidations with peroxybenzoic acid are carried out in solutions in dichloromethane, chloroform, benzene, ether, or ethyl acetate at or below room temperature and include epoxidation of double bonds [295, 296, 297, 298, 299, 300, 301], oxidation of benzaldehydes to carboxylic acids or phenols [302], the Baeyer-Villiger reaction of ketones [303, 304, 305, 306, 307], and oxidation of sulfides to sulfoxides [308, 309]. Peroxybenzoic acid is also used for the anti hydroxylation of double bonds [310], the oxidation of pyrrolidines to pyrrolidones [377] and of pyrroles to succinimides [377], and the preparation of azoxy compounds from azo compounds [372]. 

Ogata, Y., Sawaki, Y. Kinetics of the Baeyer-Villiger reaction of benzaldehydes with perbenzoic acid in aquo-organic solvents. J. Org. 

The basic sites of HT (type A in Figure 2.44) are active in the Baeyer-Villiger oxidation of various carbonyl compounds, for example, the oxidation of a substrate in the presence of O2 and an aldehyde (e.g., benzaldehyde) through the intermediate formation of a peracid. An example is the oxidation of cyclopentanone to 5-valer-olactone [275]. The base property of hydrotalcites can be tuned by changing the Mg/Al ratio and the content of interlayer anion species, for example, Cl and S04 ... 

A variety of metals have been used to promote the Baeyer-Villiger oxidation. Using catalytic metal complexes has allowed the use of inexpensive H202 or 02. Yamada and co-workers reported the use of a Ni(II) complex with 02 to promote the Baeyer-Villiger oxidation on simple ketones. In this work was reported the use of (dipivaloylmethanato)-nickel(II) to be a good complex with isovaleraldehyde or benzaldehyde under an atmosphere of 02 to provide good conversions of ketones to lactones or esters. These conditions proved to be amenable to promote the Baeyer-Villiger oxidation of a variety of ketones in 33-96% yield and is exemplified by the conversion of ketone 51 into lactone 52,29... 

Baeyer-Villiger oxidation. Cyclic ketones are converted to lactones by molecular oxygen in the presence of an aldehyde (benzaldehyde most frequently used), with or without metal catalysts. Hydrotalcite catalysts have also been evaluated. ... 

What the Beckmann rearrangement is to azepine, so is the Baeyer-Villiger oxidation to oxepine chemistry. A recent aerobic catalytic study has shown that yields of up to 95 % can be achieved with benzaldehyde and ruthenium dioxide or manganese dioxide <94SL1037>. The rate of reaction is greatly increased in the presence of lithium perchlorate without any significant loss in yield. Chiral nickel and copper complexes have been demonstrated to oxidise 2-phenylcyclohexanone... 

Baeyer-Villiger oxidation of ketones. This oxidation can be effected in high yield by oxygenation in the presence of an aldehyde (3 equiv.) and FejOj. Benzaldehyde is the aldehyde of choice but heptanal is also useful. Benzene is the only suitable solvent. 

The oxidation of thiols to disulfides with molecular oxygen has been achieved by Go(ii)-phthalocyanine complexes in [C4CiIm]BF4. Hydrogen peroxide/methyltrioxorhenium in [C4GiIm]PF6 or [G4GiIm]BF4 promotes the oxidation of hydroxylated and methoxylated benzaldehydes and acetophenones to the corresponding phenols (Scheme 26) or the Baeyer-Villiger reaction. ... 

Further examples of selective oxidations using O2 include the oxidation of -xylene to terephthalic acid, Baeyer-Villiger oxidations of cyclic ketones to lactones using molecular oxygen and benzaldehyde as a sacrificial aldehyde and catalytic epoxidation via a free radical route (rather than the electrophilic oxidation proposed for hydrogen peroxide mediated epoxidation over TS-1). ... 

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