Enantioselective N‐Heterocyclic Carbene Catalysis by the Umpolung of α,β‐Unsaturated Ketones
作者:Yuji Nakano、David W. Lupton
DOI:10.1002/anie.201510106
日期:2016.2.24
N‐Heterocycliccarbene‐catalyzed formation of β‐anionic intermediates from enones has been employed in the enantioselective synthesis of 2‐aryl propionates. The reaction was achievable using a homochiral 4‐MeOC6H4 morpholinone catalyst allowing the first example of enantioselective catalysis by umpolung of α,β‐unsaturated ketones. The reaction is high yielding, and shows robustness with reasonable
N-杂环卡宾催化由烯酮形成的β-阴离子中间体已用于2-芳基丙酸酯的对映选择性合成。该反应可以通过使用手性4-MeOC 6 H 4吗啉酮催化剂来实现,这是通过α,β-不饱和酮的负载进行对映选择性催化的第一个例子。该反应收率高,并且具有合理的一般性的稳健性。提出了一种机制,其中使用六氟异丙醇或形成的萘酚产物实现对映体确定质子化。
Asymmetric β-Boration of α,β-Unsaturated <i>N</i>-Acyloxazolidinones by [2.2]Paracyclophane-Based Bifunctional Catalyst
作者:Lei Zhao、Yudao Ma、Wenzeng Duan、Fuyan He、Jianqiang Chen、Chun Song
DOI:10.1021/ol302839d
日期:2012.11.16
An efficient copper-catalyzed asymmetric conjugate boration has been achieved by exploiting a new planar and central chiral bicyclic triazolium ligand. This protocol was highly efficient and gave a variety of chiral secondary alkylboronates in 97-99% ee. A preliminary mechanistic study supports the bifunctional nature of the catalyst.