Cooperative <i>N</i>-Heterocyclic Carbene/Lewis Acid Catalysis for Highly Stereoselective Annulation Reactions with Homoenolates
作者:Benoit Cardinal-David、Dustin E. A. Raup、Karl A. Scheidt
DOI:10.1021/ja910666n
日期:2010.4.21
A new approach that takes advantage of N-heterocyclic carbene/Lewis acid cooperative catalysis provides access to cis-1,3,4-trisubstituted cyclopentenes from enals and chalcone derivatives with high levels of diastereoselectivity and enantioselectivity. The presence of Ti(OiPr)(4) as the Lewis acid allows for efficient substrate preorganization, which translates into high levels of diastereoselectivity
一种利用 N-杂环卡宾/路易斯酸协同催化的新方法可以从具有高水平非对映选择性和对映选择性的烯醛和查尔酮衍生物中获得顺式 1,3,4-三取代的环戊烯。Ti(OiPr)(4) 作为路易斯酸的存在允许有效的底物预组织,这转化为高水平的非对映选择性。此外,我们证明了通过使用催化量的手性路易斯酸作为光学活性促进剂的独特来源来控制 NHC 催化反应的绝对立体化学的可能性。