Permanganate hydroxylation with

Fluonnated alkenes with one fluonne atom attached to the double bond are converted to a-hydroxyketones by potassium permanganate [30] (equation 22) a-Diketones are formed by permanganate hydroxylation of double bonds flanked by fluonne atoms [31] (equation 23)... 

A base-catalyzed, elimination reaction was a key step in a synthesis of D-ribose from L-glutamic acid.188 In that work, L-glutamic acid was converted, by a series of reactions, into 5-0-benzyl-2,3-dideoxy-D-glycero-pentofuranose (157) from compound 157, a mixture of glycosides was obtained which, on treatment with bromine and calcium carbonate, gave the monobromo derivative 158 as a mixture of diastereoisomers. Base-catalyzed dehydrobromination of 158 afforded the unsaturated derivative 159. Hydroxylation of 159 with potassium permanganate or with osmium tetraoxide gave a mixture of methyl 5-0-benzyl-/3-D-ribofuranoside and methyl 5-O-benzyl-a-D-lyxofuranoside. 

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. 

Pentenal was employed30 for an effective synthesis of the 2,3-di-deoxy-DL-pentose (50a). The aldehyde was converted into the dimethyl acetal 48 this was ci.s-hydroxylated with potassium permanganate to give diol 49. Mild, acid hydrolysis of 49 afforded the methyl... 

Tittle is known about the detailed mechanism of the addition of osmium tetroxide to a double bond, although the immediate product is a cyclic osmate (i) which may be decomposed to give a cw-glycol [6 ]. The addition normally follows the rule of a-attack , with the exceptions noted previously (p. 70 due to abnormal steric effects, cis-Hydroxylations with permanganate probably involve similar cyclic intermediates, although these have not been isolated... 

The results of some oxidations with potassium permanganate differ depending on the pH of the reaction. For example, stearolic acid gives 9,10-diketostearic acid at pH 7-7.5 (achieved with carbon dioxide) and azelaic acid on treatment at pH 12 [864]. In some reactions, potassium permanganate is used as a catalyst for oxidation with other oxidants, such as sodium periodate. Thus alkenes are cleaved to carbonyl compounds or acids via vicinal diols obtained by hydroxylation with potassium permanganate, followed by cleavage by sodium periodate [763, 552]. 

In Problem 7.11 we saw that hydroxylation with permanganate is syn, and hydroxy lotion with peroxy acids is anti. Keeping in mind that reaction of epoxides (Sec. 17.12 is acid-catalyzed, give a detailed mechanism for hydroxylation with peroxy acids. (Ch your answer in Sec. 17.12.)... 

Hydroxylation with permanganate gives. ry/7-addition (Problem 7.11, p. 242). To account for this stereochemistry it has been suggested that an intermediate like I is involved ... 

Diols are oxidatively cleaved by reaction with periodic acid (HIO4) to yield carbonyl compounds, a reaction similar to the KMnO cleavage of aJkenes just discussed. The sequence of (1) alkene hydroxylation with OsO< j followed by (2) diol cleavage with HIO4 is often an excellent alternative to direct alkene cleavage with ozone or potassium permanganate. 

Posternak prepared five ortlio-tetrol diastereoisomers (54, 55, 56, 60, and 61) by the appropriate cis or trans hydroxylation of ds- or trans-S-cyclohexene-l,2-diol (58 or 59). cis-Hydroxylation may be effected with permanganate or with silver chlorate-osmium tetroxide Imns-hydroxy-lation with a peroxy acid, or with silver benzoate-iodine (the Provost reagent). ... 

Sable and coworkers also synthesized all four of the predicted racemic forms of cyclopentanetetrol (131-134), and the meso diastereomer (130). The all-cfs, meso isomer is unknown. cis-Hydroxylation of the enediols (136 and 137) is effected with permanganate or with silver chlorate-osmium tetroxide Irans-hydroxylation is caused by peroxybenzoic acid. Ihe epoxy group enters ds to the neighboring, free hydroxyl group in the intermediates (136-A, 136-B, and 137-A), according to Henbest s rule. However, prior reaction of the diol structure in the intermediate (136-A) with acetone caused the epoxide group to enter trana,... 

Computations using density functional theory predict that the concerted permanganate hydroxylation of alkenes follows the 3 - - 2-cycloaddition mechanism established earlier for osmium tetroxide rather than a stepwise process involving a 2 -I- 2-cycloaddition. Calculated carbon and deuterium KIEs for a substituted case (frans-pentane-2,4-dienoic acid) are in good agreement with experimental data for frans-cinnamic acid." ... 

Carbonyl-containing and unsaturated materials are removed by treatment with sodium borohydride (227,228) and boric acid (229). Other methods used to remove carbonyl impurities include treatment with hydroxyl amine hydrochloride, potassium permanganate, or A/-hydroxyben2enesulfonamide (229). 

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