35242-02-5Relevant academic research and scientific papers
Conformational effects on lipase-mediated acylations of 2-substituted cyclohexanols
Tanikaga, Rikuhei,Matsumoto, Yoshimasa,Sakaguchi, Maki,Koyama, Yohei,Ono, Kentaro
, p. 6781 - 6783 (2007/10/03)
Lipase-mediated acetylations of trans- and cis-2-substituted cyclohexanols gave the corresponding (1R)-cyclohexyl acetates and (1S)-cyclohexanols in high yields and ee, but c-4-tert-butyl-c-2-ethenyl-r-1-cyclohexanol was unreactive owing to the steric interaction between the axial OH group and the axial H atoms at the 3- and 5-positions. In the cis-isomer the OH group occupies an equatorial position to bind to the lipase, and less bulky axial alkenyl and alkynyl groups might not so much prevent acetylations than an alkyl group.
Kinetics and Activation Parameters for the Reduction of Alkylcyclohexanones by Lithium Tri-tert-butoxyaluminohydride
Wigfield, Donald C.,Gowland, Frederick W.
, p. 653 - 658 (2007/10/02)
The kinetics of reduction of 15 cyclohexanones by lithium tri-tert-butoxyaluminohydride in tetrahydrofuran solvent are reported.The data confirm that the reaction is well represented by a simple second-order kinetic process.Second-order rate constants determined at various temperatures are recorded and the activation parameters determined.Rate constants vary from 5.0E-3 to 4.4 l mol-1 s-1; these rate constants exceed those of reduction by NaBH4 by factors varying from 50 (unhindered cyclohexanones) to 450 (hindered cyclohexanones).The reductions appear to be nearly isoenthalpic, all but three of the values of ΔH(excit.) being in the range 6.8 +/- 0.8 kcal mol-1.Variations in rates between ketones are caused by changes in ΔS(excit.), and entropy is also more significant than enthalpy in the free-energy barrier to reaction.Mechanistic aspects of the reduction are discussed.
