Cyclohexane-1,2-diol, oxidation

Chiral Alcohols and Lactones. HLAT) has been widely used for stereoselective oxidations of a variety of prochiral diols to lactones on a preparative scale. In most cases pro-(3) hydroxyl is oxidized irrespective of the substituents. The method is apphcable among others to tit-1,2-bis(hydroxymethyl) derivatives of cyclopropane, cyclobutane, cyclohexane, and cyclohexene. Resulting y-lactones are isolated in 68—90% yields and of 100% (164,165). 

Cyclohexadiene has been prepared by dehydration of cyclohexen-3-ol,3 by pyrolysis at 540° of the diacetate of cyclohexane-1,2-diol,4 by dehydrobromination with quinoline of 3-hromocyclohexene,6 by treating the ethyl ether of cyclohexen-3-ol with potassium bisulfatc,6 7 by heating cyclohexene oxide with phthalic anhydride,8 by treating cyclohexane-1,2-diol with concentrated sulfuric acid,9 by treatment of 1,2-dibromocyclo-hexane with tributylamine,10 with sodium hydroxide in ethylene glycol,10 and with quinoline,6 and by treatment of 3,6-dibromo-cyclohexene with sodium.6... 

The production of alcohols by the catalytic hydrogenation of carboxylic acids in gas-liquid-particle operation has been described. The process may be based on fixed-bed or on slurry-bed operation. It may be used, for example, for the production of hexane-1,6-diol by the reduction of an aqueous solution of adipic acid, and for the production of a mixture of hexane-1,6-diol, pentane-1,5-diol, and butane-1,4-diol by the reduction of a reaction mixture resulting from cyclohexane oxidation (CIO). 

Acidification with trichloracetic acid catalyses oxidation , the fractional increase in the rate coefficient per mole of acid added, viz. Ak/ko)/[sicid], being of the order of two. Strong catalysis by alkali metal acetates has been observed for several oxidations, e.g. of m-cyclohexane-l,2-diol °, formic acid , methyl mannoside and galactoside and several a-hydroxycarboxylic acids °. 

Retardation by acetic acid itself, which reduces the oxidation rate of trans-cyclohexane-1 2-diol by three orders of magnitude, suggests the existence of a pre-equilibrium... 

Carless HAJ, Billinge JR, Oak OZ (1989) Photochemical routes from arenes to inositol intermediates the photo-oxidation of substituted cw-cyclohexane-3,5-diene-l,2-diols. Tetrahedron Lett 30 3113-3116. 

Cyclohexene oxide (1,2-epoxycyclohexane, 10.5, Fig. 10.29) has received particular attention as a substrate for EH (see Table 10.1). The compound has a meso-cis geometry like d.v-stilbcnc oxide (10.7), and, like the latter, is hydrated preferentially to the chiral (/ ,/ )-/ran.y-cyclohexane-1,2-diol (10.124) [185], There was a difference, however, between the activities of the rabbit liver microsomal and cytosolic EHs. The former was ca. 20-fold more active than the latter toward this substrate also, it formed the (R,R)-diol with 94% enantiomeric excess (ee) compared to only 22% ee for the cytosolic EH. 

Anodic oxidation of a mixture of ds-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+. 

In 1999, Sanjuan and co-workers [27] reported a very elegant type IIavRH oxidation of cyclohexene to give a mixture of cyclohexane-1, 2-diol, 2-cyclohexenol, and 2-cyclohexenone. The reaction is initiated by excitation of the zeolite-embedded 2,4,6-triphenylpyrylium cation to produce a hydroxy radical (steps 1 and 2... 

From the NMR spectrum of copolymers produced from cyclohexene oxide and carbon dioxide it is difficult to assess low levels of asymmetric induction, i.e., low degrees of desymmetrization in the epoxide ring-opening step. In order to determine the extent of asymmetric induction it is necessary to hydrolyze the copolymer leading to the tra s-cyclohexane-l,2,-diol and examine the enantiomeric excess (4) [22]. Figure 4 shows the NMR spectrum in the carbonate region of atactic copolymer produced from cyclohexene oxide and CO2 using an achiral (salen)CrX catalyst. 

A chiral complex was used in Ru(N0)Cl(salen )/02/UV/CHCl3 for oxidative desymmetrisation of meso-diols to optically active lactols and lactones, e.g. of cis-1,2 -bis(hydroxyhnethyl)-cyclohexane to (1/ , 6S, 7/ 5)-7-hydroxy-8-oxabicyclo[4.3.0] nonane, cf mech. Ch. 1 [363],... 

Disilyl ethers of bicyclo[2.2.0]hexane-l,4-diols were transformed to cyclohexane-1,4-diones by oxidation after hydrolysis in methanol to the diols, which can be isolated.100 Sodium periodate101-103 and molecular oxygen100,101,104 were used as oxidants. 

Because organobismuth(V) compounds have found considerable use as oxidizing agents, the oxidizing ability of methyl di-l-naphthylbismuthinate [124066-66-6], C21H17Bi02, was investigated. Benzoin yields benzil, naphthalene, and metallic bismuth hydrazobenzene yields azobenzene, and 1,1,2,2-tetraphenylethanediol yields benzophenone. 1,2-Diphenyl-1,2-ethanedione dihydrazone gives diphenylacetylene in 50% yield. Cyclohexane-1,2-diol and 1-phenylethane-l,2-diol, however, were unaffected. 

A material prepared by anchoring titanium(IV) on to the walls of a high-area, crystalline mesoporous silica (MCM41) has been used as an alkene epoxidation catalyst with alkyl hydroperoxides.204 The effect of replacing one of the three O—Si= groups to which the Ti(IV) is bound by an O—Ge= group is reported to lead to an increase in catalytic activity of up to 18% in die epoxidation of cyclohexene, although no explanation is provided and it is notable diat the selectivity towards the formation of cyclohexene oxide (versus cyclohexenol and cyclohexane-1,2-diol) was inferior to that with the non-modified system.205... 

Diels-AUer reactions. This diene can serve as a precursor to the highly oxygenated cyclohexane derivative shikimic acid (3), as shown in Scheme 1. Oxidative desilylation of the Diels-Alder adduct 2 could not be effected with peracids, but was effected by cis-dihydroxylation (Upjohn procedure, 7, 256-257) followed by p-elimination of (CH3)3SiOH with TsOH. Introduction of the 4a,5P diol system was effected indirectly from the 4a,5a-epoxide in several steps, since direct hydrolysis of the epoxide resulted in a mixture of three triols.1... 

Ruthenium(VI)-catalysed oxidation of propane-1,2-diol, cyclohexane-1,2-diol, and propanetriol by alkaline HCF(III) exhibits a zero-order dependence on HCF(III) and first-order dependence on Ru(VI) and the rate increased with a decrease in alkali concentration. The reaction showed a Michaelis-Menten type of behaviour with respect to the reductant. A tentative mechanism has been proposed.63 In the ruthenium(in)-catalysed oxidation of sulfanilic acid by HCF(III) in alkaline medium, the proposed ruthenium(III) active species is [Ru(H20)50H]2+.64 Iridium(III) chloride-catalysed oxidation of diethylene glycol by alkaline HCF(III) is proposed to proceed through complex formation.65... 

Alicyclic compounds, such as cyclohexane, are also susceptible to oxidation, in this case first to cyclohexanol and then to /rans-cyclohexane-1,2-diol, cyclohexaone, and adipic acid. 

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