85114-32-5Relevant articles and documents
An examination of hyperconjugative and electrostatic effects in the hydride reductions of 2-substituted-4-tert-butylcyclohexanones
Rosenberg,Abei,Drake,Fox,Ignatz,Kwiat,Schaal,Virkler
, p. 1694 - 1700 (2007/10/03)
To better understand electronic effects on the diastereoselectivity of nucleophilic additions to the carbonyl group, a series of 2-X-4-tert-butylcyclohexanones (X = H, CH3, OCH3, F, Cl, Br) were reacted with LiAlH4. Reduction of ketones with equatorial substituents yields increasing amounts of axial alcohol in the series for X {H 3 3}. These data cannot be explained by steric or chelation ·effects or by the theories of Felkin-Anh or Cieplak. Instead, an electrostatic argument is introduced: due to repulsion between the nucleophile and the X group, axial approach becomes energetically less favorable with an increase in the component of the dipole moment anti to the hydride approach trajectory. The ab initio calculated diastereoselectivities were close to the experimental values but did not reproduce the relative selectivity ordering among substituents. For reduction of ketones with axial substituents, increasing amounts of axial alcohol are seen in the series for X {Cl 3 3 H F}. After some minor adjustments are made, this ordering is consistent with both the electrostatic model and Felkin-Anh theory. Cieplak theory cannot account for these data regardless of adjustments. Ab initio calculated diastereoselectivities were reasonably accurate for the nonpolar substituents but were poor for the polar substituents.
Regioselective dehydration in cyclic system with triphenylphosphine-azodicarboxylate
Iimori,Ohtsuka,Oishi
, p. 1209 - 1212 (2007/10/02)
The regioselective dehydration of cyclohexanol derivatives was achieved by using the Mitsunobu reagent system. The reaction undergoes under mild and neutral conditions. The observed regioselectivity was explained by considering the importance of the orientation of the leaving group at the elimination stage.
Stereochemistry of Nucleophilic Reductions of 2-Methyl-4-t-butylcyclohexanones. Further Support for the Linear Combination of SSC and PSC Stereochemical Models
Fang, Jim-Min,Sun, Shih-Feng,Rei, Min-Hon
, p. 747 - 750 (2007/10/02)
trans-2-Methyl-4-t-butylcyclohexanone reacts with lithium aluminum hydride, lithium trimethoxyaluminium hydride and methyl-lithium with equal stereoselectivity of axial attack (i. e. 95 +/- 1 percent).This is attributed to the equal steric strain control
