Synthesis of (E)-α,β-unsaturated esters with total diastereoselectivity by using chromium dichloride
作者:José M. Concellón、Humberto Rodrı́guez-Solla、Carmen Méjica
DOI:10.1016/j.tetlet.2004.02.011
日期:2004.3
Synthesis of di- and trisubstituted (E)-α,β-unsaturatedesters is easily achieved by using chromium dichloride through an elimination reaction of a diastereoisomeric mixture of α-halo-β-hydroxy esters. The starting materials were easily prepared by the aldol reaction of lithium enolates of α-chloroesters with aldehydes. A mechanism to explain this elimination process is proposed.
An efficient synthesis of (E)-α,β-unsaturated ketones and esters with total stereoselectivity by using chromium dichloride
作者:José M. Concellón、Humberto Rodríguez-Solla、Carmen Méjica
DOI:10.1016/j.tet.2006.01.052
日期:2006.4
(E)-α,β-Unsaturatedketones 1 or esters 2 can be obtained with complete stereoselectivity by reaction of different 2-chloro-3-hydroxy ketones 3 or esters 4 and CrCl2. A comparative study of the results of synthesis of ketones 1 with CrCl2 or samarium is performed. A mechanism to explain both β-elimination reactions has been proposed.