Phenol Baeyer-Villiger oxidation

Oxidation of aryl aldehydes or aryl ketones to phenols using basic hydrogen peroxide conditions. Cf. Baeyer-Villiger oxidation. 

SCHEME 159. Selenium-catalyzed Baeyer-Villiger oxidation of aromatic aldehydes and phenol formation via hydrolysis of the intermediary esters... 

Baeyer-Villiger oxidation.1 Aromatic aldehydes can be converted to phenols in generally high yield by oxidation with hydrogen peroxide (30%) activated by an areneseleninic acid. Polymethoxyacetophenones are also oxidized to phenols, but in lower yields. 

Alternative methods for the formation of the catechol (5) were examined, and these serve to show other methods for introduction of the hydroxy group. Nitration of triene (6) followed by reduction to the amine and diazotization in the presence of methanol gave the phenol (8), but only in poor yield. The best method developed appears to be acetylation of the triene (6) with titanium tetrachloride/acetyl chloride to give the ketone (9), followed by Baeyer-Villiger oxidation to die acetate (10), which on hydrolysis afforded the catechol (8) in 70% overall yield. 

Baeyer-Villiger oxidation, This reagent is generally superior to Caro s acid (monoperoxysulfuric acid) for Baeyer-Villiger oxidation. Limitations are that double bonds are attacked, that o ,/3-enones react sluggishly, and that aryl alkyl ketones are hydrolyzed to phenols. 

Syper, L. The Baeyer-Villiger oxidation of aromatic aldehydes and ketones with hydrogen peroxide catalyzed by selenium compounds. A convenient method for the preparation of phenols. Synthesis 1989, 167-172. 

The Baeyer-Villiger oxidation of aromatic ketones by peroxyacids is a widely applicable method for the synthesis of phenols . This oxidation can be carried out by organic peroxyacids such as peroxyacetic , trifluoroperoxyacetic , 4-nitro-and 3,5-dinitroperoxybenzoic acids . However, m-chloroperoxybenzoic acid is most frequently used. Hydrogen peroxide is sometimes used, but it works only in the presence of strong acids . 

The oxidation of aromatic aldehydes to phenols via the aryl formates is known as the Dakin reaction and is evidently related to the Baeyer-Villiger oxidation of ketones. The use of MCPBA is well known [45]. The successful use of MMPP and UHP-acetic anhydride in these reactions (Eqs. 34 to 36) can be achieved with aromatic aldehydes that have an electron releasing substituent in an ortho- or para-position. In the absence of a suitable electron releasing substituent, aromatic aldehydes are oxidised to the corresponding carboxylic acid. 

Phenols with p-carbonyl Substituents Acetovanillone (VI) reacted more rapidly than phenols that had no p-carbonyl substituent. The maximum rate of reaction occurred near pH 8 [88]. Strumila and Rapson [82] obtained Baeyer-Villiger oxidation products, methoxyhydroquinone and its monoacetate, from neutral peracetic acid treatment of acetovanillone. From vanillin they obtained only vanillic acid. 

Baeyer-Villiger oxidation of alkyl- and aryl-substituted C -C, cycloalkanones, steroid ketones and branched chain aliphatic ketones is catalysed by arsonated polystyrene resins [53], Larger size cycloalkanones and linear ketones react much slower. Water miscible and immiscible solvents can be used. With the latter, the resin behaves as an effective catalyst and a phase-transfer agent (triphase catalysis). The same compounds are also epoxidation catalysts. More recently, a method for the preparation of phenols by the oxidation of aromatic aldehydes and ketones has been reported. The most convenient catalysts are nitro-substituted arylseleninic acids and corresponding diselenides [54]. 

Phenols can also be prepared by combining two reactions that you have seen previously Baeyer-Villiger oxidation and ester hydrolysis. Oxidation of p-methoxyacetophenone with trifluoroperoxyacetic acid gives 4-methoxyphenyl acetate as the major product and methyl 4-methoxybenzoate as the minor one. 

Via intermediates Phenols from arenes via Yilsmeier aldehyde synthesis and Baeyer-Villiger oxidation... 

Baeyer-Villiger oxidation—Phenols from arenes—Friedel-Grafts ketone synthesis s. 19, 190 Baeyer-Villiger oxidation s. a. R. Granger, H. Orzalesi, and P. Joyeux, G.r. 260, 923 (1965)... 

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