共 22 条
Chiral Crown Conformation of Rh2(S-PTTL)4: Enantioselective Cyclopropa nation with α-Alkyl-α-diazoesters
被引:155
作者:
DeAngelis, Andrew
[1
]
Dmitrenko, Olga
[1
]
Yap, Glenn P. A.
[1
]
Fox, Joseph M.
[1
]
机构:
[1] Univ Delaware, Dept Chem & Biochem, Brown Labs, Newark, DE 19716 USA
关键词:
C-H INSERTION;
BETA-KETO-ESTERS;
DIRHODIUM(II) CARBOXYLATES;
CARBONYL YLIDES;
CYCLOADDITION REACTIONS;
RH(II) CATALYST;
CONSTRUCTION;
ADAMANTYLGLYCINE;
SELECTIVITY;
D O I:
10.1021/ja9026852
中图分类号:
O6 [化学];
学科分类号:
0703 ;
摘要:
Herein, we provide crystallographic and computational evidence that Hashimoto's Rh-2(S-PTTL)(4) catalyst adopts a "chiral crown" conformation with a reactive chiral face and an unreactive achiral face. In Rh-2(S-PTTL)(4), all four tert-butyl groups are aligned on the same face of the catalyst, and each C-(t-Bu) bond is roughly parallel. to the central Rh-Rh bond. This orients the four phthalimido groups on the opposite face of the catalyst. Also described is an enantioselective and diastereoselective protocol for intermolecular Rh-2(S-PTTL)(4)-catalyzed cyclopropanation using alpha-alkyl-alpha-diazoesters. Intermotecular cyclopropanation is selective over two competing intramolecular pathways: C-H insertion and B-hydride elimination. On the basis of density functional theory calculations and the Davies-Singleton model, for cyclopropanation, a model for asymmetric induction is proposed.
引用
收藏
页码:7230 / +
页数:3
相关论文