Trans-Cyclohexane-l,2-diol

Preparation of the Cyclic Sulfite of trans-Cyclohexane-l,2-diol [14]... 

Periodic add (or sodium metaperiodate) is often the reagent of choice when the substrate is soluble in an aqueous medium, as in the carbohydrate field an example of its use is to be found in Expt 5.117. Sodium metaperiodate supported on silica gel (Section 4.2.55, p. 454) has been found to effectively oxidise water-insoluble a-diols,106 and its value is illustrated in the preparation of hexanedial (Expt 5.78) from trans-cyclohexane-l,2-diol. 

Ti-MMM with a mesopore diameter of 3.4-3.8 nm showed fairly good activity in cyclohexene oxidation with HP in acetonitrile [35f, g]. Cyclohexene oxide and trans-cyclohexane-l,2-diol prevailed among the oxidation products. No titanium leaching... 

TABLE 4. Comparison of geometries of various derivatives of trans-cyclohexane-l,2-diol (52)... 

Transglucosylation, using different enzymes, from maltose and cellobiose to the enantiomers of trans-cyclohexane-l,2-diol gave stereochemically discrete a- and jS-monoglycosides. 

Starting from racemic trans-cyclohexan-l,2-diol by sequential KR [124]. 

If X is weakly nucleophihc (e.g., X = S04 or Cl04 ), the protonated oxirane is attacked by H2O and 1,2-diols are formed. For symmetrically substituted systems like ds-and trans-2,3-dimethyl oxirane or cyclohexene oxide, the acid-catalyzed hydrolysis follows a bimolecular SN2-hke mechanism, as indicated by its stereospecific outcome Products are rac-butane-2,3-diol, meso-butane-2,3-diol, and trans-cyclohexane-l,2-diol, respectively. 

Compound 5a possessing the C4 symmetry was reacted with WClg in benzene to produce the dichlorotungsten complex rac-19 in 81 % [7]. This complex was then resolved via diastereomeric intermediates. Thus, the reaction of rac-19 with (75,25)-trans-cyclohexane-l,2-diol gave a diastereomeric mixture of 20 and 21. Similarly, (iS,2S)-l,2-diphenylethane-l,2-diol provided a mixture of 22 and 23 in... 

The same authors have shown that independently prepared cyclohexanone enolate on treatment with borane yields trans-cyclohexane-l,2-diol in 45% yield. 2-Methylcyclohexanone, which can give two enolates under appropriate conditions, may thus be selectively converted into either a mixture of trans-diols (112) and (113) in a ratio of 42 58 or the trans-diol (114). Enol silyl ethers may also be employed as substrates for this reaction. 

Strong inductive and polar directive effects of the allylic borate group the stereospecificity at C-3 is due to a steric effect of the t-butyl group. The steric effect of the t-butyl group controls the stereochemistry of products in the hydroboration of 4-t-butylcyclohex-2-enone (119) in particular the traits directive effect of the allylic borate is overcome. Hydroboration of cyclohexa-l,3-diones gave predominantly trans-cyclohexane-l,2-diols in yields of ca. 45—50%. This... 

The reduction of cyclohexane-l,2-dione 38 (Figure 21.12) gave racemic trans-cyclohexane-l,2-diol 39 [179, 180]. From the reduction of camphorquinone 40, a 63% yield [96] of cxo-2-hydroxy camphor 41 and 3-hydroxy camphor 42 was obtained. In addition, the reduction of substituted acenaphthenequinones afforded the corresponding 2-hydroxyacenaphthenones in 24-48% yields with 10-93% ee [181]. The Wieland-Miescher ketone has also been reduced with high enantioselectivity [182]. 

Alkylation Reactions. DMF dialkyl acetals undergo a variety of reactions with 1,2-diols. For example, the reaction of trans-cyclohexane-l,2-diol with DMF dimethyl acetal leads to the formation of cyclohexane epoxide (eq 2) with inversion of configuration. Similarly, wej 0-l,2-diphenyl-l,2-ethanediol gives trans-stilbene epoxide stereospecifically (eq 3). This method has also been applied in the synthesis of cholestane epoxide from vicinal diols. If the intermediate 2-dimethylamino-1,3-dioxolane is treated with Acetic Anhydride, reductive elimination to the alkene occurs with retention of stereochemistry (eq 4). " ... 

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. 

The syntheses of (-l-)-mww,a ri,m -dicyclohexano-18-crown-6, i+)-trans-cyclohexano-15-crown-5, and (-l-)-r wis-cyclohexano-18-crown-6 (115) ftom (-l-)-mi/w-cyclohexane-l,2-diol (Figure 15) have been described. They involve base-promoted cyclizations with the appropriate ditosylates after chain extension of the chiral diol using the allylation-ozonolysis-reduction procedure. 

Triphenylbismuth carbonate (2) displays remarkable chemoselecdvity, aUowing alcohol oxidation in the presence of benzenethiol, pyrrolidine, indole, aniline, dimethyl aniline and 3-pyrolidinocholesta-3,S-diene. The diol moiety in (3) is cleaved selectively without oxidizing the dithioacetal function (equation 3). The rate of the stoichiometric oxidative cleavage of ciJ-cyclohexane-l,2-diol to adipic aldehyde with Ph3BiC03 is faster than that of the trans isomer, suggesting the formation of a cyclic organobismuth intermediate (4 Scheme 1). ... 

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. 

Cyclohexane. Dihydrodiol formation is characteristic both of saturated and aromatic cyclic hydrocarbons. The trans-A o isomer invariably is the intermediate. Eliot et al. (1959) isolated fr[Pg.258]

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... 

Butan-2,3-dione, cyclohexan-l,2-dione and phenanthraquinone react with a range of trans-1,2-dio s, including carbohydrate-based analogues, to form the 1,4-dioxane, thereby offering potential as protecting groups for the diols <97JCS(P1)2023>. 

Acid-catalyzed hydrolysis of a 1,2-epoxycyclohexane produces a trans-diaxial 1,2-diol. What product would you expect to obtain from acidic hydrolysis of c/s-3-tert-butyl-l,2-epoxycyclohexane (Recall that the bulky tert-butyl group locks the cyclohexane ring into a specific conformation.)... 

The parent 7-oxanorbomane, 1, is commercially available. Its preparation starts with the catalytic hydrogenation of hydroquinone to generate a mixture of trans-and cfs-cyclohexane-l,4-diol [15-18]. cfs-Cyclohexane-l,4-diol can be isomerized into the more stable trans isomer with metallic sodium [17]. Dehydratation of the latter on A4 zeolites, on alumina [19], or over nickel-kieselguhr catalyst [20] provides 1. This reaction is exergonic (ArG° = ArH° — TArS° = -3.1 2.5 kcal/mol) at room temperature as its standard gas phase heat of reaction amounts to ArH° = -1-7.3 2.5 kcal/mol. A variation of entropy of reaction of ca. -1-35 eu is assumed for this fragmentation, what leads to —TArS° = 298(0.035) = — 10.4 kcal/mol. The standard gas phase heat of formation of frans-cyclohexane-1,4-diol (Scheme 1) is estimated from that of cyclohexanol (—69.0 2.0 kcal/mol) and the standard heat of oxidation of cyclohexane into cyclohexanol (—39.5 kcal/ mol) [21]. Chickos and Acree [22] give AfH°(l) = -43.4 0.5 kcal/mol (see also [23-25]). 

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