Potassium permanganate epoxides

Perfluoroepoxides have also been prepared by anodic oxidation of fluoroalkenes (39), the low temperature oxidation of fluoroalkenes with potassium permanganate (40), by addition of difluorocarbene to perfluoroacetyl fluoride (41) or hexafluoroacetone (42), epoxidation of fluoroalkenes with oxygen difluoride (43) or peracids (44), the photolysis of substituted l,3-dioxolan-4-ones (45), and the thermal rearrangement of perfluorodioxoles (46). 

The oxidation of P-carotene with potassium permanganate was described in a dichloromethane/ water reaction mixture (Rodriguez and Rodriguez-Amaya 2007). After 12 h, 20% of the carotenoid was still present. The products of the reaction were identified as apocarotenals (apo-8 - to apo-15-carotenal = retinal), semi-P-carotenone, monoepoxides, and hydroxy-p-carotene-5,8-epoxide. 

Stereospecific syntheses of the 1,1-diethyl acetals 45 and 47 were performed by Makin and coworkers.29 trans-5,5-Diethoxy-2-penten-l-ol (44) was cis-hydroxylated with potassium permanganate, to yield the diethyl acetal (45) of 2-deoxy-DL-threo-pentose. Epoxidation of 44 and alkaline hydrolysis of the epoxide 46 gave the diethyl acetal (47) of 2-deoxy-DL-en/thro-pentose. 

An epoxide is formed from alkene and peroxymethanoic acid (H202 -l- HC02H) but is cleaved by the HC02H present to a frans-diol. Alternatively, osmium tetroxide may be used in fe/t-butyl alcohol and leads to the c/ s-diol. Potassium permanganate in neutral can be useful for preparation of c/ s-glycols. (See Section 11-70.)... 

An unusual regiocontrolled oxidation (epoxidation and dihydroxylation) of l-halo-1,3-dienes (equation 13) has been accomplished by use of potassium permanganate-MgSCU, after initial treatment with 2,2-dimethoxypropane78. The preferred epoxy diol is formed with the epoxide being adjacent to the chloro substituent. Further elaboration of these molecules yields highly sought after inositols with controlled stereochemistry. 

The sterically hindered character of the double bond in adamantylidene adamantane is also reflected by the fact that it is inert to oxidation by potassium permanganate and that although the corresponding epoxide may be formed, the epoxide is inert to hydrolysis conditioning. Adamantylidene adamantane glycol may be prepared, however, by treating adamantanone with sodium metal in xylene 36S). 

Whereas hydrolysis of epoxides leads to the trans diaxial addition of water and the formation of trans glycols (1,2-diols), cis glycol formation involves the addition of osmium(VIII) oxide (osmium tetroxide, OsO ) or cold dilute aqueous potassium manganate(Vll) (potassium permanganate) to an alkene. 

Cyclic vinyl epoxides are versatile building blocks (Table 11) which have been used in palladium-assisted routes to carbocyclic nucleosides. A formal synthesis of ( )-aris-teromycin101, the carbocyclic analog of adenosine, has been accomplished employing ni-tromethane as the nucleophile which serves as an acyl anion equivalent (Table 11. entry 2). The aldehyde is released by subsequent basic potassium permanganate oxidation. If nitromethane is used diluted in tetrahydrofuran, then a mixture of mono- and bis-alkylated product is formed. Whereas the alkylation of cyclohexenoxide with dimethyl malonate proceeds in a 1,4-crs fashion under palladium(O) catalysis, the 1.2-/ra/i.v-product is formed under basic conditions in the absence of the palladium(O) catalyst. 

Chromic oxide in glacial acetic acid converts tetraarylethylenes into their epoxides 54,55 and various steroids are oxidized at positions 5,6 to epoxides by potassium permanganate in glacial acetic acid.56... 

Primary alcohols are oxidized to carboxylic acids by chromium-containing reagents and to aldehydes by PCC or a Swem oxidation. Secondary alcohols are oxidized to ketones. Tollens reagent can oxidize only aldehydes. A peroxyacid oxidizes an aldehyde to a carboxylic acid, a ketone to an ester (in a Baeyer-Villiger oxidation), and an alkene to an epoxide. Alkenes are oxidized to 1,2-diols by potassium permanganate (KMn04) in a cold basic solution or by osmium tetroxide (OSO4). 

The oxidation of manool has been re-examined with the aim of producing ambergris-type perfumes. Oxidation with potassium permanganate afforded the known s methyl ketone (6), the diether (7), and at 40 °C the lactone (8). Sodium dichromate gave the aldehyde (9) as a mixture of E- and Z-isomers. Further oxidation of the methyl ketone with hypobromite gave an a-hydroxy-acid (10) and an ether (11) which was also obtained from manoyl oxide. Oxidation of the ketone with per-acid gave an acetoxy-epoxide which on reduction with lithium aluminium hydride afforded a diol. This was converted into an odoriferous ether (12). The ready formation of 5- and 6-membered-ring ethers of this type is a characteristic feature of this area of diterpenoid chemistry. 

Treatment of the 1,5-diene (Z,Z)-CHD=CHCH2CH2CH=CHD with potassium permanganate results in stereospecific oxidative cycloaddition to give 40% of the tetrahydrofuran (25), which possesses four chiral centres the (E,E)-isomer behaves in an analogous fashion. " 2,2-Dialkoxytetrahydrofurans are formed from epoxides and keten acetals thus epichlorhydrin reacts with MeCH=C(OMe)2 in the presence of zinc chloride to afford compound (26). The chloro-furanone (27) is obtained as a mixture of cis- and trans-isomers from styrene and trimethylsilyl dichloroacetate in the presence of bis(triphenylphos-phine)ruthenium(ii) chloride. Total syntheses of both enantiomers of the pheromone (28) of the Japanese beetle [Popillia japonica) and of chalcogran (29), the principal pheromone of Pityogenes chalcographus (L.), have been described. 

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