Stereocontrolled palladium-catalysed umpolung allylation of aldehydes with allyl acetates
摘要:
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.
Highly diastereoselective reactions of (E)-cinnamyl chloride with aldehydes mediated by tin and aluminium
作者:James M. Coxon、Stephen J. van Eyk、Peter J. Steel
DOI:10.1016/s0040-4039(00)95103-7
日期:1985.1
The reactions of (E)-cinnamyl chloride with aldehydes in H2O: THF: HBr in the presence of tin and aluminium powders proceed with very high stereoselectivity.
Diastereoselectivity, diastereofacial selectivity and regioselectivity in the reactions of cannamyl chloride with aldehydes mediated by tin and aluminium
作者:James M. Coxon、Stephen J. van Eyk、Peter J. Steel
DOI:10.1016/0040-4020(89)80014-6
日期:1989.1
The reaction of cinnamyl chloride witha scrics of alkyl and alkyl aldchydes mediated by tin and aluminium has been shown to be regiosclective and threo diastercosclective. For aldehydes with chirality adjacent to the carbonyl function some diastcrcofacial selectivity is observed. Conjugated aldchyydcs undergo regioselective 1,2-addition to the carbonyl.
COXON, JAMES M.;VAN, BYK STEPHEN J.;STEEL, PETER J., TETRAHEDRON, 45,(1989) N, C. 1029-1041
作者:COXON, JAMES M.、VAN, BYK STEPHEN J.、STEEL, PETER J.
DOI:——
日期:——
COXON, J. M.;EYK, S. J. VAN;STEEL, P. J., TETRAHEDRON LETT., 1985, 26, N 49, 6121-6124
作者:COXON, J. M.、EYK, S. J. VAN、STEEL, P. J.
DOI:——
日期:——
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.