188488-71-3Relevant academic research and scientific papers
Asymmetric Ring-Opening of Donor-Acceptor Cyclopropanes with Primary Arylamines Catalyzed by a Chiral Heterobimetallic Catalyst
Luo, Weiwei,Sun, Zhicheng,Nisala Fernando,Nesterov, Vladimir N.,Cundari, Thomas R.,Wang, Hong
, p. 8285 - 8293 (2019)
An efficient catalytic asymmetric ring-opening reaction of donor-acceptor cyclopropanes with primary arylamines was developed. The reaction was achieved through the utilization of a chiral heterobimetallic catalyst, delivering a variety of chiral ?3-amino acid derivatives in up to 93% yield and 99% ee. Stereochemical experiments suggest a dominant role for kinetic resolution in this asymmetric process, which is supported by a computational study of the reaction coordinate. A class of chiral bimetallic Lewis acid catalysts formed through a ligand exchange/transmetalation process was introduced in this work. The symmetric structure of the bimetallic catalyst, i.e., Yb(OTf)3-Yb[P]3, was confirmed with X-ray crystallography.
Asymmetric reduction of imines with trichlorosilane, catalyzed by sigamide, an amino acid-derived formamide: Scope and limitations
Malkov, Andrei V.,Vrankova, Kvetoslava,Stoncius, Sigitas,Kocovsky, Pavel
experimental part, p. 5839 - 5849 (2009/12/26)
(Chemical Equation Presented) Enantioselective reduction of ketimines 6-10 with trichlorosilane can be catalyzed by the N-methyl valine-derived Lewis-basic formamide (S)-23 (Sigamide) with high enantioselectivity (≤97% ee) and low catalyst loading (1-5 mol %) at room temperature in toluene. The reaction is efficient with ketimines derived from aromatic amines (aniline and anisidine) and aromatic, heteroaromatic, conjugated, and even nonaromatic ketones 1-5, in which the steric difference between the alkyl groups R1 and R 2 is sufficient. Simple nitrogen heteroaromatics (8a,b,d) exhibit low enantioselectivities due to the competing coordination of the reagent but increased steric hindrance in the vicinity of the nitrogen (8c,e) results in a considerable improvement. Cyclic imines 32d-d exhibited low to modest enantioselectivities.
