期刊
CHEMISTRY-A EUROPEAN JOURNAL
卷 16, 期 32, 页码 9910-9919出版社
WILEY-V C H VERLAG GMBH
DOI: 10.1002/chem.201001608
关键词
heterocycles; nitrones; nucleophilic addition; pyrrolidines; stem hindrance
资金
- Spanish Ministry or Science and Education (MEC Madrid Spain) [CTQ2007-67532-C02-01]
- FEDER
- Government of Aragon (Zaragoza, Spain)
- MIUR (Italy)
- Spanish Ministry of Science and Innovation (MICINN Madrid, Spain)
The diastereofacial selection in addition reactions to biased rigid systems can be modulated by the action of Lewis acids As an example. the stereoselectivity of the nucleophilic addition of vinyl magnesium bromide (VMB) to cyclic nil miles in the presence of diethylaluminum chloride (DEAC) shows a strong dependence the temperature and the carbon substituent adjacent at the reaction center, it is remarkable that whereas a high selectivity is obtained at higher temperatures. in the presence of DEAC, a trend to invert the stereochemical course of the reaction is observed at lower temperatures. provided the substituent at C3 of the pyrrolidine ring allows delivery of the vinyl moiety This behavior and difference in selectivity is to be attributed to the high conformational barriers of the intermediate nitrone-DEAC-VMB complex A clear inversion of the selectivity is observed at -78 degrees C for the reaction of the nitrone protected as an O-methyl derivative The present study provides a rationalization for the stereocontrolled addition of nucleophiles to rigid systems (cyclic nitrones)
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