Stereoselectivity in Pinacol-Homocoupling Mediated by Samarium Diiodide
作者:Peter G�rtner、Max Knollm�ller、Joachim Br�ker
DOI:10.1007/s00706-003-0061-x
日期:2003.12.1
The stereoselectivity of the pinacol-coupling of various substituted benzaldehydes mediated by samariumdiiodide was investigated. The dependence of product-ratios, yields, and stereoselectivities on the substrate, the substrate-reagent-ratio, and the solvent is described.
Treatment of aromatic carbonyl compounds with Zn powder in 10% aq NaOH solution without using any organic solvents under the mild conditions afforded the corresponding 1,2-diols in good yields.
An electrochemical method to prepare solutions of samarium diiodide in THF is reported. The simple electrolysis of a samarium rod provides a rapid and straightforward in situ synthesis of SmI2. The electrogenerated complex catalyzes various CC bond formations. The reagent is produced continuously (see scheme) and leads to efficient organic electrosynthesis with significantly smaller amounts of solvent
A monomeric titanium(III) complex, TiCl3(tmeda)(thf) (1), has been prepared by a reaction of TiCl4 with TMEDA, Zn, and a catalytic amount of PbCl2 in an almost quantitative yield. The solid state structure of 1 is revealed by X-ray crystallographic analysis. The complex 1 couples aromatic aldehydes under mild conditions to give 1, 2-diols in good to excellent yields with high dl-selectivities.