期刊
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
卷 136, 期 4, 页码 1367-1380出版社
AMER CHEMICAL SOC
DOI: 10.1021/ja4082233
关键词
-
资金
- NSERC
- OGS
- OGSST
- Canada Foundation for Innovation under Compute Canada
- Canada Foundation for Innovation under Government of Ontario
- Canada Foundation for Innovation under Ontario Research Fund - Research Excellence
- Canada Foundation for Innovation under University of Toronto
After their treatment with LiAlH4 and then alcohol, new iron dicarbonyl complexes mer-trans-[Fe(Br)-(CO)(2)(P-CH=N-P')][BF4] (where P-CH=N-P' = R2PCH2CH=NCH2CH2PPh2 and R = Cy or iPr or P-CH=N-P' = (S,S)- Cy2PCH2CH=NCH(Me)CH(Ph)-PPh2) are catalysts for the hydrogenation of ketones in THF solvent with added KOtBu at 50 degrees C and 5 atm H-2. Complexes with R = Ph are not active. With the enantiopure complex, alcohols are produced with an enantiomeric excess of up to 85% (S) at TOF up to 2000 h(-1), TON of up to 5000, for a range of ketones. An activated imine is hydrogenated to the amine in 90% ee at a TOF 20 h(-1) and TON 99. This is a significant advance in asymmetric pressure hydrogenation using iron. The complexes are prepared in two steps: (1) a one-pot reaction of phosphonium dimers ([cyclo-(PR2CH2CH(OH)(-))(2)][Br](2)), KOtBu, FeBr2, and Ph2PCH2CH2NH2 (or (S,S)-Ph2PCH(Ph)CH-(Me)NH2 for the enantiopure complex) in THF under a CO atmosphere to produce the complexes cis- and trans-[Fe(Br)(2)(CO)(P-CH=N-P')]; (2) the reaction of these with AgBF4 under CO(g) to afford the dicarbonyl complexes in high yield (50-90%). NMR and DFT studies of the process of precatalyst activation show that the dicarbonyl complexes are converted first to hydride-aluminum hydride complexes where the imine of the P-CH=N-P' ligand is reduced to an amide [P-CH2N-P'](-) with aluminum hydrides still bound to the nitrogen. These hydride species react with alcohol to give monohydride amine iron compounds FeH(OR')(CO)(P-CH2NH-P'), R' = Me, CMe2Et as well as the iron(0) complex Fe(CO)(2)(P-CH2NH-P') under certain conditions.
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