Diphosphination of Electron Poor Alkenes
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- 作者：Imre Hajdk† ; ; Falk Lissner† ; ; Martin Nieger‡ ; ; Sabine Strobel† ; ; Dietrich Gudat*† ;
- 刊名：Organometallics
- 出版年：2009
- 出版时间：March 23, 2009
- 年：2009
- 卷：28
- 期：6
- 页码：1644-1651
- 全文大小：195K
- 年卷期：v.28,no.6(March 23, 2009)
- ISSN：1520-6041
文摘
Studies of the reactions between an unsymmetrically substituted 1,1-diaminodiphosphine and electron poor alkenes revealed that, in contrast to the regioselective 1,2-addition of the P−P bond to α,β-unsaturated esters and nitriles with terminal double bonds, ethyl(vinyl)ketone reacted via 1,4-addition and α,β-unsaturated esters or ketones with internal double bonds failed to react at all, presumably owing to the deactivating influence of the alkyl groups. Reaction of 1 with maleic N-phenylimide proceeded stereoselectively under cis-addition but diesters of maleic and fumaric acid gave mixtures of diastereomeric 1,2-bisphosphines. The addition products were characterized by 31P NMR before being converted into palladium complexes that were isolated and comprehensively characterized by spectroscopic data and in most cases by X-ray diffraction studies. Monitoring the reactions of 1 with maleic and fumaric diesters by NMR revealed that both E/Z-isomerization of alkene starting materials and epimerization of stereogenic centers in 1,2-bisphosphines take place and allow isolation from the mixtures of diastereomeric ligands of complexes featuring a uniform stereochemistry of the C2 backbone.