Enantioselective Morita–Baylis–Hillman reaction promoted by l-threonine-derived phosphine–thiourea catalysts
作者:Xiaoyu Han、Youqing Wang、Fangrui Zhong、Yixin Lu
DOI:10.1039/c1ob05881a
日期:——
A series of bifunctional phosphineâthiourea organic catalysts based on natural amino acid scaffolds were designed and prepared. L-Threonine-derived bifunctional phosphine catalysts were found to be very efficient in promoting asymmetric MoritaâBaylisâHillman (MBH) reaction of acrylates with aromatic aldehydes, affording the desired MBH adducts with up to 90% ee. To gain mechanistic insights into the reaction, the effects of adding various additives on the MBH reaction were investigated. We propose that the hydrogen bonding interactions between the thiourea moiety of the catalyst and the enolate intermediate are crucial for the stereochemical outcome of the reaction. The method described in this report may provide a practical solution to the enantioselective MBH reaction of simple acrylates.
我们设计并制备了一系列基于天然氨基酸支架的双功能膦硫脲有机催化剂。研究发现,L-苏氨酸衍生的双功能膦催化剂在促进丙烯酸酯与芳香醛的不对称莫里塔-贝利斯-希尔曼(MBH)反应方面非常有效,可以得到所需的 MBH 加合物,ee 值高达 90%。为了深入了解该反应的机理,我们研究了添加各种添加剂对 MBH 反应的影响。我们认为,催化剂的硫脲分子与烯醇中间体之间的氢键相互作用对反应的立体化学结果至关重要。本报告所述方法可为简单丙烯酸酯的对映选择性 MBH 反应提供实用的解决方案。