Hydroxylation of cyclohexene

C. Hydroxylation of Cyclohexene with Hydrogen Peroxide-Formic Acid 8, 9)... 

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. ... 

Scheme 3.22 Proposed rebound mechanism shown forthe hydroxylation of cyclohexene la [109].

Payne and Smith59 studied the hydroxylation of cyclohexene with a mixture of 34% hydrogen peroxide and a little tungstic acid in acetone. In addition to trans-1,2-cyclohexanediol, they obtained a 25% yield of 3,3-dimethyl -1,2,4-trioxaacetone derivative of the intermediate hydroxyhydroperoxide. Hydrogenation of 71 leads to tm w-cyclo-hexane-l,2-diol. 

Turbulent stirring and the presence of low concentrations of sodium hydroxide are very beneficial in improving the yield of cir-l,2-cyclohexanediol from the hydroxylation of cyclohexene with potassium permanganate. " Presumably, hydroxylation of other alkenes with this reagent would also benefit by attention to these factors. 

Although catalyst B is simpler to prepare than catalyst A, it should not be used if the diol is to be distilled directly from the reaction mixture, since residual sodium chlorate can cause explosions when heated with an organic compound. Hydroxylation of allyl alcohol with catalyst A gave glycerol in 67% yield. ri.t-Cyclohcxaiic-l,2-diol was obtained in 76% yield by hydroxylation of cyclohexene with catalyst B. 

Another DFT study on hydroxylation of cyclohexene catalysed by manganese oxoporphyrin suggests the physisorption of the substrate over the catalyst molecule followed by the abstraction of H from the C—H bond by the oxo group of the catalyst. The cyclohexene radical is readily bound to the OH group formed at the active site of the catalyst. Alcohol is formed on the catalyst active site via oxygen rebound mechanism without the dissociation of cyclohexene radical. ... 

The allylic hydroxylation of cyclohexene catalyzed by sMMO is accompanied by the allylic rearrangement (20%), as described above [69]. In addition, in the case of oxygenation of terminal olefins, the detected alcohols are only the primary alcohols as shown in eqs. (22) and (23) [75]. This means that all of the carbon radical intermediates must undergo the allylic rearrangement. It seems inadequate to explain the results of eqs. (22) and (23) (the allylic rearrangement of 100%) only by the thermodynamic stability of the inner olefin, and necessary to consider an alternative mechanism which can explain the formation of both allylic alcohol and epoxide in the oxygenation of olefin vide post). 

A clean, solvent-free method has been developed for the bis-hydroxylation of alkenes by the use of Nafion-based acidic catalysts and 30% H202.655 Nafion NR50 and SAC-13 exhibited high activity in the oxidation of isomeric C alkenes, cyclohexene [Eq. (5.228)], 1,4-cyclohexadiene, and allylic alcohols in the temperature... 

Alternatively and more conveniently this ds-hydroxylation process can be effected using only catalytic amounts of osmium tetroxide together with hydrogen peroxide, which cleaves the first formed osmate ester to the diol and regenerates the osmium tetroxide. The reaction is carried out in t-butyl alcohol and is illustrated by the conversion of cyclohexene into ds-cyclohexane-l,2-diol (Expt 5.47). 

Then, pseudo-p-DL-gulopyranose (14) was synthesized by hydroxylation of 2,5-di-hydroxy-3-cyclohexene-l-methanol triacetate (12), which was prepared by Diels-Alder cycloaddition of 1,4-diacetoxy- 1,3-butadiene (10) and allyl acetate (11), with osmium tetroxide and hydrogen peroxide and successive acetylation as the pentaacetate (13). Analogous hydrolysis of 13 in ethanolic hydrochloric acid afforded the free pseudosugar 14 in 33% yield from 12 [2] (Scheme 7). 

HYDROXY-1-CYCLOHEXENE-1-CARBOXALDEHYDE 1-CYCLOHEXENE-1 -CARBOXALDEHYDE, 3-HYDROXY- (67252-14-6), 67, 205 (S)-(+)-3-HYDROXY-2,2-DIMETHYLCYCLOHEXANONE Cyclohexanone, 3-hydroxy-2,2-dimethyl-, (S)- (87655-21-8), 68, 56 Hydroxylamine, N-phenyl-, 67, 187 a-Hydroxylation of ketones, 66, 138... 

Results for the oxidation of cyclohexene, 1,3,3-trideuterocyclo-hexene (5) and 3,3,6,6-tetradeuterocyclohexene (6) are given in Table II. It is apparent from the large increase in the relative amount of cyclohexene oxide upon deuteration of the allylic hydrogens that the hydroxylation path has a significant hydrogen-isotope effect... 

The hydroxylation of aliphatic C-H bonds can be performed exclusively by CPO [65-67]. A direct oxygen transfer mechanism has been suggested, as the oxygen atom arises from the peroxide. The reaction requires an activated C-H bond since hydroxylation occurs at the ally lie or benzylic positions. Both cyclic (cyclohexene)... 

Osmium tetroxide is also a catalyst in the oxidation of the double bond by chlorates. Cis addition of hydroxyl groups takes place as is shown by the preparation of cis-l,2-cyclohexanediol from cyclohexene and the formation of the proper diastereoisomeric dihydroxy derivatives of maleic, fumaric, and 4-halocrotonic acids. Silver chlorate is preferred to potassium chlorate in the hydroxylation of crotonic acid. ... 

The cyclopentadiene dimer, when treated with potassium permanganate and triethylbenzylammonium chloride as a phase-transfer agent, furnishes an 83% yield of exo,cis-diol resulting from the hydroxylation of the double bond in the cyclohexene ring [900] (equation 82). 

---