2- Phenylcyclohexanol

Selenski investigated the use of chiral enol ether auxiliaries in order to adapt method F-H for enantioselective syntheses. After surveying a variety of substituted and unsubstituted enol ethers derived from a vast assortment of readily available chiral alcohols, she chose to employ enol ethers derived from trans-1,2-phenylcyclohexanol such as 73 and 74 (Fig. 4.37). These derivatives were found to undergo highly diastereoselective cycloadditions resulting in the formation of 75 and 76 in respective... 

Treatment of either the cis or trans isomer of 4-/m-bu(yl-1 -phenylcyclohexanol with trifluoroacetic acid and one of a variety of organosilicon hydrides in dichloromethane yields a mixture of cis- and trans-4-tert-butyl-l-phenyl-cyclohexane and the elimination product, 4-/er/-butyl -1 -phenylcyclohexene... 

Substituted 3-hydroxy-2-pyrrolidinones were synthesised via 1,3-DC reactions of furfuryl nitrones with acrylates and subsequent intramolecular cyclisation after N-0 bond reduction. Addition of iV-acryloyl-(2/()-bomane-10,2-sultam to Z-nitrone 83 gave the endo/exo cycloadducts in 85 15 ratio with complete stereoface discrimination <00JOC1590>. The 1,3-DC of pyrroline A-oxide to chiral pentenoates using (-)-/rans-2-phenylcyclohexanol and (-)-8-phenylmenthol as chiral auxiliaries occurred with moderate stereocontrol (39% de and 57% de, respectively) and opposite sense of diastereoselectivity <00EJO3595>. The... 

Enantioselective [2 + 2 cycloaddition.2 The chiral allylic ether (1), prepared from (lS,2R)-( + )-2-phenylcyclohexanol, undergoes enantioselective cycloaddition with dichloroketene to furnish, after one crystallization, optically pure (-)-2. This cyclobutanone after ring expansion and exposure to chromium(II) perchlorate gives... 

An enantioselective intramolecular Pauson-Khand reaction based on chiral auxiliary-directed 7t-face discrimination in acetylenic 0-alkyl enol ether-dicobalt hexacarbonyl complexes, which proceeds with good yields and high facial diastereoselectivity, has recently been developed by M.A. Pericas, A. Moyano, A.E. Greene and their associates. The method has been applied to an enantioselective formal synthesis of hirsutene. Moreover, the process is stereodivergent and the chiral auxiliary -rran5-2-phenylcyclohexanol- is recovered in a yield as high as 92% [18]. 

The other enantiomer, (+)-(1S,2fl)-trans-2-phenylcyclohexanol, was also prepared by this procedure. The crude mass of the alcohol was 39.15 g (95.8% ee), while after recrystalli/ration, the yield was 29.80 g (69%) of materieil with the following properties mp 64-66°G, >99.5% ee (see Note 7 for data). The reaction appears to be scaleable... 

In scaling up this procedure, the biggest improvement in the overall yield was achieved by omitting the crystallization of the intermediate diol. The trans-2-phenylcyclohexanol, which forms relatively large crystals, is easier to handle lhan the diol, which is a very fluffy powder. Analysis of the final product was carried out by both CSP-HPLC and CSP-SFC methods. 

SYNTHESIS OF (+)-(1S,2fl)- AND -H1B,2S)-trans-2-PHENYLCYCLOHEXANOL VIA SHARPLESS ASYMMETRIC DIHYOROXYLATION (AD)... 

The progress of the reaction may be followed by TLC using 1 3 ethyl acetate/petroleum ether and visualization with anisaldehyde stain. The diol appears at an ff, = -0.3 (stains olive-brown) the 2-phenylcyclohexanol appears at an R, = -0.6 (stains blue). The checkers found that the use of a needle outlet at the top of the condenser helped to maintain a smooth reflux and prevented leakage though the stirring assembly. 

Enantiomerically pure trans-2-phenylcyclohexanol, first used by Whitesell as a chiral auxiliary has become a popular reagent in a number of asymmetric transformations. Some recent applications include asymmetric azo-ene reactions, [4 + 2]-cycloaddition reactions, ketene-olefin [2 + 2]-reactions, enolate-imine cyclocondensations, Pauson-Khand reactions," palladium annulations and Reformatsky reactions. Despite its potential, use of this chiral auxiliary on a preparative scale is currently limited by its prohibitive cost. 

The Birch reduction of dibenzofuran is reported to give 1,4-dihydro-dibenzofuran. The electrochemical reduction of dibenzofuran by solvated electrons is reported to produce a dihydrodibenzofuran and a tetrahydro-dibenzofuran, both of unspecified structure. Treatment of dibenzofuran with W-7 Raney nickel in boiling methanol gave a moderate yield of trans-2-phenylcyclohexanol, whereas treatment of dibenzofuran with Raney nickel alloy and aqueous sodium hydroxide gave a low yield of 2-biphenylol. ... 

Supercritical CO2 and 15 different solvents Esterification of racemic 1-phenylcyclohexanol [93]... 

Early efforts using a chiral auxiliary, such as a chiral acetal or 2-phenylcyclohexanol, resulted in modest diastereoselectivity. - ... 

The technique of chiral auxiliaries was exploited in a synthesis of cholesterol absorption inhibitors, based on an imino-Reformatsky reaction between bromoacetates of chiral alcohols (e.g. 69a and 69b) and imine 70. Virtual complete asymmetric induction was found with (-)-trans-2-phenylcyclohexanol and (—)-phenyl substituted menthol derived chiral auxiliaries (equation 43)126. 

Because of the lack of ready access to 2, Whitesell et al.2 recommend trans-2-phenylcyclohexanol (3) as an auxiliary. Hydrolysis of the acetate of ( + )-3 with hog liver esterase provides optically pure (- )-3,aD - 56° and (+ )-3,aD + 54°. The glyoxylate ester of 3 undergoes ene reactions with high diastereoselectivity. 

Methyl-5-phenyl-3-(3-phenylpro-pionyl)-2-oxazolidone, 24 (S)-l-[l-Methyl-2-pyrrolidinyl]-methylpiperidine, 116, 302 Methyl p-tolyl sulfoxide, 115 Norephedrine, 200 2-Oxazolidones, chiral, 24, 225, 267 (2R,4R)-Pentanediol, 205, 237 /r[Pg.403]

LIPASE-CATALYZED KINETIC RESOLUTION OF ALCOHOLS VIA CHLOROACETATE ESTERS (-)-(1R,2S)-trans-2-PHENYLCYCLOHEXANOL AND (+)-(1S,2R)-trans-2-PHENYLCYCLOHEXANOL... 

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