Synthesis of Chiral Pyridylphenols for the Enantioselective Addition of Diethylzinc to Aldehydes
作者:Pei-Shan Wu、Chinpiao Chen
DOI:10.1002/jccs.201100474
日期:2012.6
Chiral 8‐substituted 2‐(8,10,10‐trimethyl‐6‐aza‐tricyclo[7.1.1.02,7]undeca‐2(7),3,5‐trien‐5‐yl)‐phenols were prepared from a high enantiopurity (>97% ee) of (1R)‐(+)‐α‐pinene, and assessed in the enantioselectiveaddition of diethylzinc to substituted benzaldehydes, giving the (S)‐alcohols with enantiomeric excess ranging from 33% to 89%. Interestingly, in all cases, except for those of ortho‐chlorobenzaldehyde
probe this and to enlarge the very narrow catalytic scope of these Lewis bases, easily accessible mono- and bidentate phosphotriesters were tested as donors in two important transition metal-based catalytic transformations: the zinc-catalyzed hydrosilylation of ketones and the titanium-promoted diethylzinc addition to aldehydes. In both cases, the reactions were successful and the corresponding alcohols
SYNTHESIS, STRUCTURE AND USE OF BISOXAZOLIDINES FOR ASYMMETRIC CATALYSIS AND SYNTHESIS
申请人:Wolf Christian
公开号:US20070265255A1
公开(公告)日:2007-11-15
One aspect of the invention relates to chiral bisoxazolidines and their use in asymmetric catalysis. The chiral bisoxazolidines are a novel class of compounds that is expected to find multiple applications, for example, in asymmetric synthesis. For example, a bisoxazolidine ligand enabled the catalytic enantioselective alkynylation and alkylation of a range of aromatic and aliphatic aldehydes, generating chiral propargylic alcohols and secondary alcohols in high yields and enantiomeric excess.
Grignardreagents were generated from magnesium and organic iodides in the ionic liquid n-butylpyridinium tetrafluoroborate, [bpy][BF4], and they showed different reactivity from classical Grignardreagents in organic solvents.
Chiral Aryl Pyridyl Alcohols as Enantioselective Catalysts in the Addition of Diethylzinc to Substituted Benzaldehydes
作者:Tien-Chu Chang、Chinpiao Chen
DOI:10.1002/jccs.200800088
日期:2008.6
(1/R)-(+)-α-pinene (> 97% ee), and applied in the enantioselective addition of diethylzinc to substitutedbenzaldehydes, to yield alcohols with the (S)-configuration with an enantiomeric excess that typically ranges from 19 to 86%. Importantly, the electron-withdrawing substituents at the meta-position of the substitutedbenzaldehydes exhibited high enantioselectivity during alkylation using diethylzinc