Cis-l,2-Cyclohexane diol

Free cyclohexene from peroxides by treating it with a saturated solution of sodium metabisulphite, separate, dry and distil collect the fraction having b.p. 81-83°C. Mix 8.2 g (0.1 mol) of cyclohexene with 55 ml of the reagent (0.1 mol), add 3 ml of a 0.5 per cent solution of osmium tetroxide [CAUTION (1)] in anhydrous t-butyl alcohol and cool the mixture to 0°C. Allow to stand overnight, by which time the initial orange coloration will have disappeared. Remove the solvent and unreacted cyclohexene by distillation at atmospheric pressure and fractionate the residue under reduced pressure using an air condenser. Collect the fraction of b.p. 120-140 °C/15 mmHg this solidifies almost immediately. Recrystallise from ethyl acetate. The yield of pure cis-cyclohexane-l,2-diol, m.p. 96 °C, is 5.0g (45%). 

Anodic oxidation of a mixture of cis-cyclohexane-l,2-diol and cyclohexanol in methanol containing dibutyltin oxide and Et4NBr provides 2-hydroxycyclohexanone selectively, while cyclohexanol is recovered almost completely (Fig. 28) [146]. The cyclic intermediate dibutyl-(l,2-dioxycyclo-hexyl) stannan is oxidized indirectly by Br" ". 

Relative rate studies of cyclic cis- and trans-l 2-diols give no clear pattern of results. C -cyclohexane-l 2-diol is oxidised by V(V) faster than the trans isomer, but the reverse is found for the isomers of 1 2-dimethylcyclohexane-1 2-diol. 

Obviously with the indan-l,2-diol substrates there is no symmetrical meso intermediate which makes interpretation of the mechanism more difficult. In both the cyclohexan-l,2-diol and the indan-l,2-diol series the trans diols react faster and cis diols (both enantiomers for indandiol) are seen as intermediates. The (IS,2R) cis indandiol 29 is faster reacting and on incubation of the racemate only a very small trace of the R,R)-trans 28 isomer is observed. 2-Hydroxyin-dan-1 -one 30, an observed intermediate in these biotransformations, undergoes kinetic resolution when incubated as a racemic substrate. The faster reacting enantiomer is reduced to the faster reacting cis (lS,2i )-indan-l,2-diol 29 which is subsequently transformed into both trans diols and ultimately the (S,S)-iso-mer. Current work is focussing on determining the absolute configuration of the intermediate a-hydroxyketone 30. 

Stirring for about 1 hr. the temperature rose to 40°, and benzaldehyde separated in an oily layer. The reagent is not specific to m-glycols monoprotic alcohols and aldehydes are oxidized by silver-catalyzed persulfate. Kinetic study of the cleavage of CIS- and tran j-cyclohexane-l,2-diol showed strikingly identical rates of reaction for both isomers. 

These reagents were developed by Criegee for the characterization of vic-diols. Dipotassium tetramethylosmate (1) is a crystalline green solid readily made from osmium tetroxide and methanolic potassium hydroxide. It reacts in methanol with cis-diols and also with sufficiently flexible tranj-diols. tranj-Cyclohexane-l,2-diol,... 

Miscellaneous Cyclohexanes. Various reactions involving hydroxylation of cyclohexane derivatives have been reported. The reaction of cyclohexanol with Fe(C10 )2 and hydrogen peroxide in acidic aqueous MeCN solutions has been shown to be very sensitive to the exact concentrations of Fe", Fe ", and perchloric acid. In MeCN, cis-cyclohexane-l,3-diol forms 72% of the product diol, i.e. hydrogen removal at C-3 occurs with some stereoselectivity cis to the hydroxy-group. In highly aqueous solutions, the dominant oxidation site is at C-4. Evidence is presented for a stepwise process involving an initial directed hydrogen abstraction, oxidation of the radical by Fe" , and stereoselective carbonium ion capture. 

Octahydro- (we have used this nomenclature throughout) or perhydrobenzo[c]thiophene (35) exists as the cis and trans isomers and is more commonly named 2-thiahydrindane or 8-thiabicyclo-[4.3.0]nonane. Each stereoisomer may be prepared by treating the corresponding isomer of l,2-di(bromomethyl)cyclohexane with sodium sulfide (details of the products are given in Table IV).45 Cyclization of the cis isomer may be effected partially with thiourea via the formation of cis-hexahydro-o-xylylenebis(isothiouronium bromide) with sodium disulfide it gives a mixture of cis-octahydro-benzo[c]thiophene and cis-2,3-dithiadecalin.46 Optically pure ( —)-(8 R,9I )-lran -octahydrobenzo[c]thiophene has been prepared from (+ )-dicarboxylic acid via reduction of the diacid to the diol, tosylation, and ring closure of the bistosylate with sodium sulfide.47... 

The O18 exchanges accompanying the pinacol rearrangement in the cyclohexane-1,2-diol and cyclopentane-l,2-diol systems have also been investigated. The pinacolic rearrangement of both cis- (17) and trans-1,2-dimethylcyclohexane-l,2-diol (18) in aqueous acid gives 1-acetyl-methylcyclopentane and a small amount of 2,2-dimethylcyclohexanone... 

We have observed that diol 3, cis-2-butene-l,4-diol, and cis-1,2-bis(hydroxymethyl)cyclohexane react smoothly with TPP-CClq to afford 4 (78%), 2,5-dihydrofuran (65%), and cis-8-oxabicyclo[4.3.0]-nonane 84%). Reaction of diol 5 with TPP-CCli in CH3 CN gives 52% of 5-chloropentanol, 6 (11%), and 1,5-dichloropentane (25%) while diol 7 affords 6-chlorohexanol (48%) and 1,6-dichlorohexane (39%). Comparisons of the ether chlorohydrin dichloride product distributions arising from these simple diols reveal a trend for efficiency of chain closure to 3 - 7 membered rings where the formation of cyclic ethers appear to decrease in order of the following ring size 3-5>6>4-7. 

Enzymatic dihydroxylation of toluene by Pseudomonas putida affords (-t-)-cis-l, 2-dihy-droxy-3-methyl-3,5-cyclohexadiene) (Figure 33). The relative stereochemistry was determined to be ds, but the absolute configuration was unknown, until determined by Ziffer et al. [43] Catalytic reduction of the diene gave a stereochemically well-resolved cyclohexane diol suitable for introducing the benzoate chromophore. The dibenzoate gave a (-) exciton chirality CD, and thus the organism produces the diene-diol shown in Figure 33(a). 

We next became interested in the possibility of extending this to a seven-membered cyclic ketal. It was immediately recognized that if the yield of the cyclic compound were not nearly quantitative, the resulting polymer would be cross-linked. In our previous work (16) the cis- and trans-l,2-bis (hydroxymethyl)-cyclohexane were prepared. When either the cis- or trans-diol was condensed with 1,4-cyclohexanedione, a 92% yield of the corresponding model compound was obtained. 

In the course of time, a great many crystalline organic substances have been discovered which, upon recrystallisation from a suitable solvent, form gels instead of depositing crystals. Examples are dibenz-oyl-l-cystine (upon pouring its alcoholic solution in water), camphoryl phenyl thio semicarba ide (by recrystallisation from toluene) Azomethine (upon recrystallisation from organic solvents), 1. cyclohexyl cyclohexane cis 1.2 diol (upon recrystallisation from water). Lithium urate and others. 

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