Hydrogen peroxide with selenium dioxide

The preparation of Pans-1,2-cyclohexanediol by oxidation of cyclohexene with peroxyformic acid and subsequent hydrolysis of the diol monoformate has been described, and other methods for the preparation of both cis- and trans-l,2-cyclohexanediols were cited. Subsequently the trans diol has been prepared by oxidation of cyclohexene with various peroxy acids, with hydrogen peroxide and selenium dioxide, and with iodine and silver acetate by the Prevost reaction. Alternative methods for preparing the trans isomer are hydroboration of various enol derivatives of cyclohexanone and reduction of Pans-2-cyclohexen-l-ol epoxide with lithium aluminum hydride. cis-1,2-Cyclohexanediol has been prepared by cis hydroxylation of cyclohexene with various reagents or catalysts derived from osmium tetroxide, by solvolysis of Pans-2-halocyclohexanol esters in a manner similar to the Woodward-Prevost reaction, by reduction of cis-2-cyclohexen-l-ol epoxide with lithium aluminum hydride, and by oxymercuration of 2-cyclohexen-l-ol with mercury(II) trifluoro-acetate in the presence of ehloral and subsequent reduction. ... 

Sideritis (Labiatae) species have continued to attract attention as a source of diterpenoids. n/-lljS,18-Dihydroxykaur-15-ene (49) was obtained from 5. chamaedryfolia and the known diterpenoids foliol (enr-3/8,7a,18-trihydroxy-kaur-16-ene) and its 3- and 18-monoacetates (sidol and linearol) were detected in S. arborescens ° and along with their A -isomers and 18-hydroxykaur-16-ene (candol B) in S. flavovirens. A similar group of hydroxykaurenes was found in S.funkiana whilst enr-18-acetoxy-3jS,6a,7a-trihydroxykaur-15-ene (funkiol) and the isomeric 3-acetate (sidofunkiol) were amongst the minor constituents. The selective allylic oxidation of the kaur-16-enes at C-15 by hydrogen peroxide and selenium dioxide is facilitated by the presence of a 7-hydroxy-group. 

A mixture of 1,4-dioxane and water is often used as the solvent for the conversion of aldehydes and ketones by H2Se03 to a-dicarbonyl compounds in one step (Eq. 8.117).331 Dehydrogenation of carbonyl compounds with selenium dioxide generates the a, (i-unsaturated carbonyl compounds in aqueous acetic acid.332 Using water as the reaction medium, ketones can be transformed into a-iodo ketones upon treatment with sodium iodide, hydrogen peroxide, and an acid.333 Interestingly, a-iodo ketones can be also obtained from secondary alcohol through a metal-free tandem oxidation-iodination approach. 

Oxidation of 2,3-dimethylquinoxaline (from phenylenediamine and diacetyl) with either peracids or hydrogen peroxide in acetic acid gives the 1,4-dioxide (162). Treatment of this bis-N-oxide with selenium dioxide leads to oxidation of one of the methyl groups to the methyl carbinol and formation of... 

Figure 3.60 Ring contraction of cyclic ketones with selenium dioxide in the presence of hydrogen peroxide.

Cyclopenteaediol isomers have previously been prepared by hydrolysis of acetates produced by reaction of dibromocyclopen-tene with potassiiun acetate in acetic acid by reaction of cyclo-pentene with selenium dioxide in acetic anhydride or by reaction of cyclopentadiene with phenyl iodosoacetate/ with lead tetraacetate, or with peracetic acid in the absence of base. Preparation of cydopentenediol without intermediate formation of acetates has been accomplished by reaction of cyclopentadiene with hydrogen peroxide in the presence of osmium tetroxide in terf-butanol, and hy reaction of cyclopentadiene with peracetic acid in a methylene chloride suspension of anhydrous sodium carbonate, followed by hydrolysis of the resulting epoxycyclo-pentene. ... 

Finally we note that oxidation of a saturated 3-ketone (30) with selenium dioxide/hydrogen peroxide gave the isomeric lactones (31) and (32) in ratio 4 3, apparently by a nonspecific Baeyer-ViHiger type of reaction [66]. 

A PS-peroxyselenic acid (29) was prepared by treatment of PS-mercury(II) chloride (30) with selenium dioxide followed by 30% hydrogen peroxide (Scheme 10). In a triphase system, consi ting of (29) (1.5 mol %), 1.5-1.8 equivalents of 30% aqueous hydrogen peroxide and dichloromethane, alkenes were oxidized to 1,2-diols, and ketones to esters or lactones. The polymeric seleninic acid (31) could be reoxidized to the PS-peroxyseleninic acid (29) and recycled with no apparent loss of activity. 

ALLYLIC OXIDATION WITH HYDROGEN PEROXIDE-SELENIUM DIOXIDE frans-PINOCARVEOL... 

Treatment of 73 with selenium metal at 360° yields dibenzothio-phene. Oxidation of 73 with hydrogen peroxide was accompanied by partial dehydrogenation yielding 1,2,3,4-tetrahydrodibenzothiophene 5,5-dioxide (68). ... 

The pyrazine ring is stable toward permanganate oxidation, and this explains a variety of pyrazinecarboxylic acids that have been prepared from quinoxalines or benzo-fused quinoxalines. In contrast, alkyl side chains on pyrazines are effectively oxidized by permanganate, selenious acid, selenium dioxide, or dichromate to afford the corresponding carboxylic acids (Section 8.03.7.1). Oxidation of pyrazines with hydrogen peroxide or percarboxylic acids gives pyrazine A -oxides and/or A, A -dioxides (Section 8.03.5.2). 

Oxidation of the sulfur- or selenium-bridged azepines (171 X=S or Se) with mercury(II) oxide in methanol yields ultimately the 4f/-azepine (68JCS(C)23ll) with hydrogen peroxide as oxidant, the sulfur compound furnishes the sulfoxide (171 X=SO). Selenium dioxide oxidation of 7,8-dimethyl-lf/-l-benzazepin-2-one affords the 2,3-dioxo derivative (173) that displays no evidence of enol tautomers or heteroaromaticity (7ici(L)1439). 

Phenanthrenequinone has been prepared by treatment of phe-nanthrene with chromic acid in acetic acid 5 potassium dichromate in sulfuric acid 3-6 hydrogen peroxide in acetic acid 6 7 and selenium dioxide above 250°.8 It can also be prepared from benzil with aluminum chloride at 120° 9 and from biphenyl-2,2 -dialdehyde with potassium cyanide.10... 

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