Practical hydroxymethylation of aldehydes and ketones via pinacol cross-coupling reactions with paraformaldehyde
作者:Jeonghan Park、Steven F. Pedersen
DOI:10.1016/s0040-4020(01)88875-x
日期:——
method for the direct hydroxymethylation of aldehydes and ketones via pinacol cross-coupling with paraformaldehyde is described. The reaction is promoted by vanadium(II) ions which are conveniently generated from the reduction of VCl3(THF)3 with zinc dust. Excellent yields of terminal diols are obtained and stereoselective coupling is observed with some chiral aldehydes and ketones.
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