Zeng Xingzhong, Hu Qian, Qian Mingxing, Negishi Ei-ichi
Herbert C. Brown Laboratories of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907-2084, USA.
J Am Chem Soc. 2003 Nov 12;125(45):13636-7. doi: 10.1021/ja0304392.
The Pd-catalyzed cross-coupling reaction of 2-bromo-1,3-dienes derived from alkyl aldehydes, especially with Cl2Pd(DPEphos) as a catalyst, proceeds with clean stereoinversion of the Br-bearing C=C bond to produce in high yields and in high stereoselectivity (>/=97-98%) conjugated Z,E dienes of potentially high utility in the synthesis of complex natural products. The observed stereoinversion cannot be readily accommodated by the widely accepted pi-sigma-pi rearrangement mechanism for isomerization of ordinary allylpalladium derivatives.
由烷基醛衍生的2-溴-1,3-二烯的钯催化交叉偶联反应，特别是以二（二苯基膦）二氯化钯（Cl2Pd(DPEphos)）作为催化剂时，含溴碳碳双键会发生完全的立体翻转，以高收率和高立体选择性（≥97 - 98%）生成共轭Z,E-二烯，这些二烯在复杂天然产物的合成中可能具有很高的实用性。对于普通烯丙基钯衍生物的异构化，广泛接受的π-σ-π重排机理难以轻易解释所观察到的立体翻转现象。
