Torsional, Rotor, and Electronic Effects in 4-<i>tert</i>-Butylmethylenecyclohexane Epoxidations and Osmylations
作者:E. Vedejs、W. H. Dent、J. T. Kendall、P. A. Oliver
DOI:10.1021/ja953040p
日期:1996.1.1
The axial epoxidation preference for 2-substituted 4-tert-butylmethylenecyclohexanes is attributed to a combination of small effects, including existing bond torsion and rotor effects. Contributions from developing bond torsion are smaller and may be negligible. Cieplak (σ−σ*) effects are too small to identify in most of the epoxidations, but a marginal effect could be present according to comparisons
cis- and trans-2-Methylene-5-t-butylcyclohexanols are obtained in high (>90%) e.e. through Rabbit Gastric Lipase (RGL)-catalyzed acylation or hydrolysis of the stereoisomeric racemicalcohols or their corresponding acetates. Since these reactions were diastereomer-selective, enantiomerically enriched cis- and trans-5-t-butyl-2-methylenecyclohexanols could also be prepared from cis/trans isomeric mixtures