An experimental and theoretical study of the mechanism of stannylcupration of α,β-acetylenic ketones and esters

被引：11

作者：

Ahlquist, M ^{[1
]}

Nielsen, TE ^{[1
]}

Le Quement, S ^{[1
]}

Tanner, D ^{[1
]}

Norrby, PO ^{[1
]}

机构：

[1] Tech Univ Denmark, Dept Chem, DK-2800 Lyngby, Denmark

来源：

CHEMISTRY-A EUROPEAN JOURNAL | 2006年 / 12卷 / 10期

关键词：

alkynes; cuprates; density functional calculations; stannylcupration; stereoselectivity;

D O I：

10.1002/chem.200501229

中图分类号：

O6 [化学];

学科分类号：

0703 ;

摘要：

The title reaction has been investigated by experimental and computational (DFT) techniques, and subsequently compared to the corresponding carbocupration reaction, with particular emphasis oil the stereoselectivity. For stannylcupration of an ynone substrate, only the anti-addition product is observed, whereas for the corresponding ynoate substrate, the stereoselectivity can be affected by the reaction conditions: in the presence of methanol as proton donor, the initial syn-addition product can be trapped, whereas a syn/anti mixture is obtained in a non-protic solvent. This is in sharp contrast to the carbocupration of the same ynone substrate with a cyanocuprate (RCu(CN)Li), which is highly selective for syn-addition. The product selectivities can be understood from a detailed computational characterization of the reaction paths, and in particular from the relative stabilities of the vinyl cuprate and allenolate intermediates. It is suggested that the stereodetermining step is protonation of vinyl cuprate intermediates.

引用

页码：2866 / 2873

页数：8

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