Phenyl-1,2-ethanediol

Styrene glycol dimesylate [ 1,2-Ethanediol, 1-phenyl-, dimethylsulfonate], 55,... 

Since double bonds may be considered as masked carbonyl, carboxyl or hydroxymethylene groups, depending on whether oxidative or reductive methods are applied after cleavage of the double bond, the addition products from (E)-2 and carbonyl compounds can be further transformed into a variety of chiral compounds. Thus, performing a second bromine/lithium exchange on compound 4, and subsequent protonation, afforded the olefin 5. Ozonolysis followed by reduction with lithium aluminum hydride gave (S)-l-phenyl-l,2-ethanediol in >98% ee. 

Several fluoro analogs of ketoses have been reported 1,6-dideoxy-1,6-difluoro-D-fructose was readily obtained from 2,3-O-isopropyli-dene-l,6-di-0-p-tolylsulfonyl-)3-D-fructofuranose by treatment with potassium fluoride in 1,2-ethanediol under a stream of carbon dioxide.96 Surprisingly, although the 6-sulfonyloxy group would be expected to be more reactive than the 1-sulfonyloxy group,97-99 no selectivity was observed. The failure to obtain 1-deoxy-l-fluoro-D-fructopyranose96 from 2,3 4,5-di-0-isopropylidene-l-0-(methylsulfonyl) (or p-nitro-phenylsulfonyl)-/3-D-fructopyranose or phenyl 3,4,5-tri-O-acetyl-l-O-(methylsulfonyl)-/3-D-fructopyranoside by treatment with potassium or sodium fluoride in 1,2-ethanediol, N,N-dimethylformamide, or form-amide at elevated temperatures may be attributed to the fact that nu-... 

Monoalkyl ethers of (R,R) 1,2-bis[3,5-bis(trifluoromethyl)phenyl]ethanediol, 24, have been examined for the enantioselective protonation of silyl enol ethers and ketene disilyl acetals in the presence of SnCU (Scheme 12.21) [25]. The corresponding ketones and carboxylic acids have been isolated in quantitative yield. High enantioselectivities have been observed for the protonation of trimethylsilyl enol ethers derived from aromatic ketones and ketene bis(trimethylsilyl)acetals derived from 2-arylalkanoic acids. 

After exposure to atmospheres containing 300 and 600 ppm [1.30 and 2.60 g/m ] ethylbenzene for 6 h, Wistar rats excreted 83% and 59% of the estimated dose as ethylbenzene metabolites in the urine in 48 h, respectively. The principal metabolites were 1-phenylethanol, -hydroxyacetophenone and phenylacetic, mandelic, phenylglyoxylic and benzoic acids, accompanied by smaller amounts of 1-phenyl-1,2-ethanediol, phenylglyoxal, acetophenone and/ ara-hydroxyacetophenone (Engstrdm, 1984b). 

The stereochemical aspects of the fates of 1-phenyl-1,2-ethanediol and mandelic acid in rats have been examined by Drummond et al. (1990). The proportions of a dose of 1-phenyl-1,2-ethanediol converted to phenylglyoxylic and mandelic acids depend upon its stereochemistry. The i -diol is preferentially converted to i -mandelic acid (30% of the dose in 48 h) with 15% of the dose as phenylglyoxylic acid. In contrast, after administration of the 5 -diol, the major product is phenylglyoxylic acid (46% of the dose) with 16% as mandelic acid (JUS 80 20). 

The vibrational circular dichroism(VCD) spectroscopy can be used to elucidate the stereochemistries of chiral molecules, including the accurate estimation of enantiomeric excess and their absolute configrations[20]. Optically pure samples as well as a racemic sample(c) were used as a reference to compare the VCD spectra. Three VCD spectra are shown in Fig. 7 a spectrum of 99 % ee R(-)-1-phenyl 1,2-ethanediol(a) and that of 99 % ee S(+ )-1-phenyl l,2-ethanediol(b) obtained from Aldrich Co., and the other is that of the product obtained on the Ti-MCM-41/chiral Co(HI) salen catalyst(d). 

Fig.7. Vibrational circular dichroism(VCD) spectra of R(-)-l-phenyl 1,2-ethanediol, S( + )-l-phenyl 1,2-ethanediol and racemic 1-phenyl 1,2-ethanediol.

Exercise 16-44 Strong acid converts 1,1 -diphenyl-1,2-ethanediol first to diphenyl-ethanal and then more slowly to 1,2-diphenylethanone (benzyl phenyl ketone). Explain how and why kinetic and equilibrium control may be expected in this case to give different products. 

Diaryl ketones do not undergo photodissociation in the same way as alkyl ketones, probably because cleavage to phenyl and other aryl radicals is unfavorable (Table 4-6). Nevertheless, aromatic ketones are photochemically reactive in the presence of compounds that can donate a hydrogen atom, with the result that the carbonyl group is reduced. Indeed, one of the classic photochemical reactions of organic chemistry is the formation of 1,1,2,2-tetraphenyl-1,2-ethanediol (3, benzopinacol) by the action of light on a solution of diphenyl-methanone (2, benzophenone) in isopropyl alcohol. The yield is quantitative. 

C. Wandrey, and U. Kragl, Enzymic resolution of 1-phenyl-1,2-ethanediol by enantioselective oxidation overcoming product inhibition by continuous extraction, Biotechnol. Bioeng. 1996, 51, 544-550. 

Fig. 13.—Formation and equilibration of acyl derivatives from the dibutylstannylene acetal of l-phenyl-l,2-ethanediol and their subsequent trapping reactions.53...

Phenyl-1,2-ethanediol Acetal CHCI3 Amb. Benzoyl chloride6 86 5 84... 

Chromium-salen complexes have been used for the reaction between styrene epoxide and scC02 in [C4Ciim][PF6], as illustrated in Scheme 9.15.1601 At low catalyst concentrations, 1-phenyl-1,2-ethanediol was detected as a by-product while at a catalyst loading of ca. 0.35 mol%, 100% selectivity was obtained. Recycling of the catalyst was possible, but the ionic liquid phase needed to be exhaustively purified with volatile organic solvents prior to its reuse. 

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