Asymmetric catalysis: A facileenantioselective Strecker reaction of ketimines with trimethylsilyl cyanide (TMSCN) was realized by employing chiral (S)‐BNPNa 3 e and PBAP as an additive (see image). A wide substrate scope and good‐to‐excellent enantioselectivities were achieved.
作者:Ji Hye Kim、Ilija Čorić、Sreekumar Vellalath、Benjamin List
DOI:10.1002/anie.201300120
日期:2013.4.15
In straitened circumstances: In an asymmetric version of the acid‐catalyzed acetalization of aldehydes, a novel member of the chiral confined Brønsted acid family significantly outperformed previously established catalysts, providing cyclic acetals with excellent enantioselectivity (see scheme; Ar=2‐iPr‐5‐MeC6H3).
在僵化的情况下:在醛的酸催化乙缩醛的不对称形式中,手性约束布朗斯台德酸家族的新型成员显着优于以前建立的催化剂,提供了具有出色对映选择性的环状环状缩醛(见方案; Ar = 2- i Pr- 5-MeC 6 H 3)。
The Long-Arm Effect: Influence of Axially Chiral Phosphoramidite Ligands on the Diastereo- and Enantioselectivity of the Tandem 1,4-Addition/Fluorination
作者:Lian Wang、Wei Meng、Chuan-Le Zhu、Yan Zheng、Jing Nie、Jun-An Ma
DOI:10.1002/anie.201104565
日期:2011.9.26
Long arm of the law: The long‐armed phosphoramidite 1 was used as a catalyst for the title reaction of acyclic alkylidene β‐ketoesters with dialkylzinc and fluorinating reagents. The products, containing adjacent carbon‐ and fluorine‐substituted stereocenters, are obtained in high yield as well as diastereo‐ and enantioselectivity. NSFI=N‐fluorobenzenesulfonimide.
By using a combination of a chiral N‐triflyl phosphoramide and TiCl4 as the catalyst, a new process for asymmetric intramolecular hydroalkoxylation of unactivated alkenes was developed, producing various chiral tetrahydrofuran derivatives in 51%—99% yields with 30%—71% ee's.