A Method for the Asymmetric Hydrosilylation of N-Aryl Imines
摘要:
[GRAPHICS]The asymmetric reduction of N-aryl imines to yield chiral amines with enantiomeric excesses above 90% was achieved. Ethylenebis(eta(5)-tetrahydroindenyl)titanium difluoride ((EBTHI)TiF2, 1) was employed as the precatalyst with polymethylhydrosiloxane (PMHS) as the stoichiometric reducing agent. A variety of N-aryl imines derived from nonaromatic ketones were reduced with high ee.
Asymmetric reduction of ketimines with trichlorosilane employing an imidazole derived organocatalyst
作者:François-Moana Gautier、Simon Jones、Stephen J. Martin
DOI:10.1039/b816051a
日期:——
Organocatalysts for the asymmetric reduction of ketimines are presented that function well at low catalyst loadings providing chiral amines in good yield and enantioselectivity, the latter appearing to be independent of the ketimine substrate geometry.
Catalytic Enantioselective Amination of Alcohols by the Use of Borrowing Hydrogen Methodology: Cooperative Catalysis by Iridium and a Chiral Phosphoric Acid
作者:Yao Zhang、Ching-Si Lim、Derek Sui Boon Sim、Hui-Jie Pan、Yu Zhao
DOI:10.1002/anie.201307789
日期:2014.1.27
synthesis of chiral amines, with reductants ranging from Hantzsch esters, silanes, and formic acid to H2 gas. Alternatively, the amination of alcohols by the use of borrowing hydrogen methodology has proven a highly atom economical and green method for the production of amines without an external reductant, as the alcohol substrate serves as the H2 donor. A catalytic enantioselective variant of this
Enantiomericallypure chiral amines are of increasing importance and commercial value in the fine chemical, pharmaceutical, and agrochemical industries. Here, we describe the straightforward synthesis of chiral amines by combining the atom‐economic and environmentally friendly hydroamination of alkynes with an enantioselective hydrogenation of in situ generated imines by using inexpensive hydrogen
Organocatalysis with a Fluorous Tag: Asymmetric Reduction of Imines with Trichlorosilane Catalyzed by Amino Acid-Derived Formamides
作者:Andrei V. Malkov、Marek Figlus、Sigitas Stončius、Pavel Kočovský
DOI:10.1021/jo062215i
日期:2007.2.1
Asymmetricreduction of ketimines 1 with trichlorosilane can be catalyzed by N-methylvaline-derived Lewis-basic formamides 3a−d with high enantioselectivity (≤95% ee) and low catalyst loading (1−5 mol %) at room temperature in toluene. Appending a fluorous tag, as in 5a−c, simplifies the isolation procedure, while preserving high enantioselectivity (≤92% ee).
Control with an iron hand: A broad range of ketimines underwent enantioselectivehydrogenation in the presence of a chiralBrønsted catalyst and a well‐defined nonchiral iron catalyst (see scheme). This procedure constitutes an attractive and environmentally favorable alternative to well‐established asymmetric hydrogenation reactions with precious‐metal catalysts.