期刊
CHEMISTRY-AN ASIAN JOURNAL
卷 6, 期 2, 页码 510-516出版社
WILEY-V C H VERLAG GMBH
DOI: 10.1002/asia.201000596
关键词
density functional calculations; Friedel-Crafts reactions; indoles; nitroalkenes; phosphoric acid
资金
- JSPS [20750082]
- Grants-in-Aid for Scientific Research [20750082] Funding Source: KAKEN
The enantioselective Friedel-Crafts reaction of indoles with nitroalkenes proceeds catalytically by means of a chiral-phosphoric-acid catalyst to afford products with high enantioselectivities (up to 91% ee). The use of a 3,3'-SiPh3-substituted (R)-binol-derived (binol=1,1'-binaphthyl-2,2'-diol) catalyst and a free indole that bears an N-H moiety is essential to achieving high enantioselectivity as well as high yield. To elucidate the reaction mechanism and the origin of the high enantioselectivity, DFT calculations were carried out. The reaction proceeded through a cyclic transition state formed by the two-point binding of both substrates to the conjugated O-P-O moiety of the catalyst, in which indoles and nitroalkenes could be simultaneously activated by Bronsted acidic (proton) and basic (phosphoryl oxygen) sites, respectively. The enantioselectivity was entirely controlled by the steric effect between the 3,3'-substituent group on the (R)-binol-derived phosphoric acid catalyst and the indole ring. When the sterically demanding SiPh3 group was used as the 3,3'-substituent group, the energy difference between the moststable diastereomeric transition states that afforded the S and R products was increased to lead to the high enantioselectivity in agreement with the experimental results.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据