Stereocontrolled palladium-catalysed umpolung allylation of aldehydes with allyl acetates
作者:Monika Vogt、Sascha Ceylan、Andreas Kirschning
DOI:10.1016/j.tet.2010.04.133
日期:2010.8
In the present work the stereocontrolled palladium-catalysed umpolung allylation of aldehydes is described. Allyl acetates are in situ transformed into the corresponding allyl boronates, which directly react with aldehydes. The question of stereocontrol is raised by employing (a) chiral boronating agents (reagent control) and by (b) utilising chiral aldehydes (substrate control). These studies reveal that the approach based on substrate control is superior to the former one with respect to yields and stereo-selectivity. Remarkably, this umpolung protocol often yields the 4,5-syn products in high selectivity, which is unprecedented for direct crotylations. (C) 2010 Elsevier Ltd. All rights reserved.