2-Cyclohexene-l,4-diol

A typical preparation of the polycarbonates is shown for polymer III in Scheme I. 1,4-Benzenedimethanol is activated by reaction with two equivalents of p-nitrophenyl chloroformate in pyridine and the resulting symmetrical dicarbonate is then used in a polycondensation with an equimolar amount of 2-cyclohexen-l,4-diol in a solid-liquid phase-transfer catalyzed reaction with 18-crown-6 as catalyst and solid anhydrous potassium carbonate as base. Alternately, the same polymer can be prepared by condensation of bis(4-nitrophenyl)-2-cyclohexen-1,4-ylene dicarbonate [12] with 1,4-benzenedimethanol or through a variety of similar polycondensations using diol biscar bonylimidazolides [13,14]. 

Reaction of the bis-p-nitrophenylcarbonate of 1,4-benzenedimethanol with 2-cyclohexen-l,4-diol A mixture is prepared under argon atmosphere, consisting of 1.1348 g (9.954 mmoles) of the diol, 4.6623 g (9.954 mmoles) of the bis-p-nitrophenyl carbonate 0.630 g of 18-crown-6, 7.0 g of potassium carbonate and 15 mL of dry dichloromethane. The reaction mixture is stirred and refluxed for 90 hours, after which time it is worked-up by the usual method. Three precipitations into 1.5 liter of methanol are necessary to obtain 2.760 g (91% yield) of the pure white polymer. The cis trans ratio of the cyclohexenediol units in polymer III is shown to be 35 65 by H-NMR reflecting the mixture used initially. 

Polycarbonates based on 2-cyclohexen-l,4-diol and a dihydroxy compound liberate benzene through aromatization, a dihydroxyl compound, and carbon dioxide, upon acidolysis [343]. The low volatility of the dihydroxyl compound hampers complete development by heating alone and necessitates wet development. 

Reduction of epidioxides. Schenck and Dunlap used thiourea for reduction of epidioxides, obtained by 1,4-addition of singlet oxygen to conjugated dienes at low temperatures, to the corresponding diols. Kaneko et al. report that the diols can be obtained in one step by irradiation of the diene with singlet oxygen in the presence of thiourea. Under these conditions irradiation can be conducted conveniently at room temperature. This procedure was used to prepare cw-2-cyclopentene-l,4-diol and cw-2-cyclohexene-l,4-diol. 

Cyclohexene-l,4-diol, 586 Cyclohexene epoxide, 71, 333, 466, 488 Cyclohexene-3-ol, 428 Cyclohexenone, 21 Cyclohexenones, 371 2-(3-Cyclohexenyl)ethanol, 637 N-Cyclohexenylmotpholine, 433 Cyclohexylamine, 230 Cyclohexylideneacetaldehydes, 357 Cyclohexylidenecyclohexane, 171 Cyclohexylidenethyl bromide, 327, 328 Cyclohexyl isocyanide, 129, 152... 

A cyclic allylic azide is required for a synthesis of (-i-)-pancratistatin. This intermediate is obtainable from a Pd-catalyzed reaction of MCjSiNj with a meso-2-cyclohexene-l,4-diol dicarbonate in the presence of a chiral ligand. 

Scheme 15 Preparation of supraminol complexes 29 35 and 29 36 from the (R,R)-trans-1,2-diaminocyclohexane (29) and (/ ,/ )-4-cyclohexene-l,2-diol (35) and (R,R,R,R)-4, 5-dibromocyclohexane-1,2-diol (36).

Similar results were obtained in the recognition process between (i ,i )-39 and (i ,i )-4-cyclohexene-l,2-diol (35) [60], The motif of the crystal core of the complex 39 35 is a right-handed helical ribbon while the outer core adopts a left-... 

Acyl esters of vicinal diols are obtained by the reaction of alkenes with metal carboxylates [436]. Lead tetraacetate in acetic acid at 70 °C converts 1,2-dihydronaphthalene to rranj-l,2-diacetoxy-l,2,3,4-tetrahy-dronaphthalene in 72% yield [436]. The reaction is not always stereospecific. Cyclohexene treated with thallium triacetate gives a mixture of diastereomers in varying ratios, depending on reaction conditions, and byproducts as a result of rearrangements (equation 89) [411],... 

We close this section with a brief mention of 2,4-dinitrosobenzene-l,3-diol or 5-cyclohexene-l,2,3,4-tetrone-l,3-dioxime or yet some other tautomer studied as a solid... 

The catalyst was prepared from the conesponding chiral diol and TiCl2(OPr-z )2 at room temperature in the presence of 4 A molecular sieves. Without molecular sieves, stoichiometric amounts of the titanium complex were required to obtain an equally high enantioselectivity. A remarkable solvent effect was observed. Various cycloadducts were only obtained with high optical yields when non-polar solvents were cmployctl -. For example. 4-substituted4-cyclohexene-l,2-dicarboxylate derivatives 408 were obtained with ee values ranging from 91 to 94% in the reactions of 91a, 399 and 407 with 17b in toluene/... 

Regioselective Diels-Alder reactionsThe intramolecular [4+2]cycloaddition of 2, prepared by reaction of a vinylsilane with the diunsaturatcd alcohol 1, provides an adduct (3), which on oxidative dcsilylation provides the cyclohexenes 4 and S with marked preference for the d.v-l,3-diol 4. 

Graft copolymers between unsatnrated acids, especially acrylic acid and maleic anhydride (MA), and polyolefins (PE and PP) are widely used as surface modifiers and compatibilisers, sometimes in combination with bi-functional coupling agents [46], for talc, calcium carbonate and calcined clays. Such polymer coatings include polypropylene-maleic anhydride [47], polypropylene c/s-4-cyclohexene-l,2 dicarboxylic acid [48], polystearyl or polylauryl acrylate [49], polypropylene-acrylic acid, partially oxidised poly(butane diol) [50] and ethylene-vinyl acetate copolymers [51]. Acid-containing products can react with basic fillers. With most other types, they will simply adsorb on to the mineral surface, but they can form esters with some non-basic metal hydroxyls, notably silanols. 

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. 

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