Evolution of chiral Lewis basic N-formamide as highly effective organocatalyst for asymmetric reduction of both ketones and ketimines with an unprecedented substrate scope
作者:Li Zhou、Zhouyu Wang、Siyu Wei、Jian Sun
DOI:10.1039/b703307a
日期:——
L-Pipecolinic acid derived Lewis basic N-formamide has been developed as a first highly effective catalyst for the asymmetric reduction of aromatic and aliphatic ketones as well as aromatic and aliphatic ketimines in good to high enantioselectivity.
l-Pipecolinic acid derived Lewis base organocatalyst for asymmetric reduction of N-aryl imines by trichlorosilane: effects of the side amide group on catalytic performances
作者:Zhouyu Wang、Chao Wang、Li Zhou、Jian Sun
DOI:10.1039/c2ob26772a
日期:——
A series of N-formamides derived from pipecolinic acid have been synthesized and tested as Lewisbase catalysts for the enantioselective reduction of N-aryl imines by trichlorosilane. Through the investigation of the structure–efficacy relationship between the side amide group and catalytic performance, several highly effective catalysts were discovered. In particular, arylamido-type catalyst 5i and
The hydrogenation of imines to amines in the presence of catalytic amounts of zinctriflate has been demonstrated for the first time. In addition, an efficient procedure for the reductivehydroamination of alkynes to amines is presented using zinctriflate as a catalyst precursor. In both protocols a variety of different functional groups are tolerated, and the reactions proceed smoothly in high yields
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.