Regioselective opening of epoxy alcohols: mild chemo- and stereoselective preparation of iodohydrins and 1,2-diols
作者:Carlo Bonini、Giuliana Righi、Giovanni Sotgiu
DOI:10.1021/jo00021a045
日期:1991.10
Several 2,3-epoxy alcohols have been opened, at -60-degrees-C, with MgI2, leading to the corresponding 3-iodo 1,2-diols with a high level of regio- and chemoselectivity. The iodohydrins can be reduced "in situ", by means of nBu3SnH, to the corresponding 1,2-diols. The chemo-, regio-, and stereocontrol of the reaction makes the method of wide use. Furthermore, epoxy alcohol derivatives (acetyl, benzyl, or TBMS) still maintain a strong preference for C-3 attack of the nucleophile. The experimental data strongly suggest that a metal (Mg) centered chelate is formed throughout the reaction, which gives rise to the regioselective delivery of the iodide ion.
Regioselective reduction of epoxides by electron transfer—a photochemical approach
作者:Gary A. Epling、Qingxi Wang
DOI:10.1039/c39920001133
日期:——
Irradiation of epoxides in the presence of amines and sodium borohydride leads cleanly to a regioselective opening of the epoxide, giving the lesser substituted alcohol as a product.