Cyclohexanone, reduction

Wu, Y.-D. Tucker, J. A. Houk, K. N. Stereoselectivities of nucleophilic additions to cyclohexanones substituted by polar groups. Experimental investigation of reductions of trans-decalones and theoretical studies of cyclohexanone reductions. The influence of remote electrostatic effects, J. Am. Chem. Soc. 1991,113, 5018-5027. 

Felkin identified torsional effects in cyclohexanone reductions that accounted for the observed stereoselectivity. Minimization of these torsional effects, in the absence of steric hindrance, led to the predominance of axial attack (equation 2).- Recently, a computational approach has provided quantitative support for this model.- The eclipsing interactions between the incoming nucleophile and the bonds a to... 

The relative rate for cyclohexanone reduction was set at 100. This would give, for example, a total relative rate of 24 for the reduction of 2,3,5,6-tetrahydro-2-... 

The reaction proceeds under phase-transfer conditions (benzyltriethylam-monium chloride and 18-crown-6) at 28°C. After 2.5 hr, cyclohexanol is formed with 78% conversion (catalytic turnover 20) (119). With Ru3(CO)12, methanol can be used as the hydrogen source for the cyclohexanone reduction a large excess of triphenylphosphine increases the conversion considerably. After 18 hr at 150°C, 44% of cyclohexanol was formed, corresponding to a catalytic turnover of 44 (120). 

N. G. Gaylord, Reduction with Complex Metal Hydrides. Interscience, New York (1956) H. C. Brown, Boranes in Organic Chemistry, Cornell Univ. Press, Ithaca, NY (1972), pp 209-250 H. 0. House, Modem Synthetic Reactions, Benjamin, New York (1972), p 49 Chem Soc Rev 5 23 (1976) Tetr 35 449 (1979) (stereochemistry and mechanism) Topics Stereochem 11 53 (1979) (stereochemistry) JACS 103 4540 (1981) (stereochemistry of cyclohexanone reductions) J. Seyden Penne, Reductions by the Alumino- and Borohydrides in Organic Synthesis, VCH-Lavoisier (1991), Chpt 2 Comprehensive Organic Synthesis, Eds. B. M. Trost and I. Fleming, Pergamon, Oxford (1991), Vol 8, Parts 1.1 and 1.7 TL 34 5483 (1993) (stereochemistry) ... 

The product stereochemistry and rates of reduction by sodium borohydride in propan-2-ol at various temperatures have been investigated for a number of 2-sub-stituted cyclohexanones. Reduction of 2,6-dimethylcyclohexanone gave rise to... 

Following is an aldol reaction between nitromethane and cyclohexanone. Reduction of the nitro group in the aldol product thus formed is a convenient synthetic route to S-aminoalcohols. 

Contrary to the reduction of amino-2-cyclohexanones, reduction of 2-amino-cyclopentanones with LaAlH4 and NaBH occurs by preferential trans attack of H . The effect of the cation was also in the opposite sense to that observed for the cyclohexanones. The results indicate two competing mechanisms involving a cyclic intermediate, favoured by hard cations, or a dipolar transition state. 

The main feature of the Meerwein-Ponndorf-Verley reaction pathway involves the coordination of both reactants to the Lewis-acid metal eentre and hydride transfer from the alcohol to the earbonyl group. Aluminium or titanium alkoxides are usually effective homogeneous catalysts. With tin-Beta catalyst, cyclohexanone reduction with 2-butanol led selectively to cyclohexanol at 100 °C. Ketone conversion was >95%, whereas silicon-Beta, Sn02/Si02 and SnCl4 -5H20 were inaetive under the same experimental conditions. Therefore, the activity is likely due to tetrahedral tin in the zeolite framework, and not to extra-framework tin or to leached tin. ... 

The terms approach control and product development control as applied to cyclohexanone reductions have been redefined in a relative sense with... 

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