[EN] CATALYTIC ASYMMETRIC SYNTHESIS OF OPTICALLY ACTIVE alpha-HALO-CARBONYL COMPOUNDS [FR] SYNTHESE ASYMETRIQUE CATALYTIQUE DE COMPOSES DE DOLLAR G(A)-HALO-CARBONYLE OPTIQUEMENT ACTIFS
The enantioselective aminocatalytic α-chlorination of aldehydes is a challenging reaction because of its tendency to proceed through neutral intermediates in unselective pathways. Herein we report the rational shift to a highly selective reaction pathway involving charged intermediates using hexafluoroisopropanol as solvent. This change in mechanism has enabled us to match and improve upon the yields
Forming Stereogenic Centers in Acyclic Systems from Alkynes
作者:Roxane Vabre、Biana Island、Claudia J. Diehl、Peter R. Schreiner、Ilan Marek
DOI:10.1002/anie.201504756
日期:2015.8.17
This method provides access to functionalized products in which three new carbon–carbon bonds and two to three stereogenic centers, including a quaternary one, were created in acyclicsystems in a single‐pot operation from simple alkynes.
The direct organocatalytic enantioselective α-chlorination of aldehydes has been developed. The reaction proceeds for a series of different aldehydes with NCS as the chlorine source using easily available catalysts such as l-proline amide and (2R,5R)-diphenylpyrrolidine. The α-chloro aldehydes are obtained in up to 99% yield and up to 95% ee. The synthetic utility of the enantioselective α-chlorination
[EN] CATALYTIC ASYMMETRIC SYNTHESIS OF OPTICALLY ACTIVE alpha-HALO-CARBONYL COMPOUNDS<br/>[FR] SYNTHESE ASYMETRIQUE CATALYTIQUE DE COMPOSES DE DOLLAR G(A)-HALO-CARBONYLE OPTIQUEMENT ACTIFS
申请人:HALLAND NIS
公开号:WO2005080298A1
公开(公告)日:2005-09-01
A process for the catalytic asymmetric synthesis of an optically active compound of the formula (la) or (lb): wherein R is an organic group; X is halogen; Rl and R2which may the same or different represents H, or an organic group or Rl and R2 may be bridged together forming part of a ring system; R and R2 may be bridged together forming part of a ring system; with the provisio that R and Rl are different and R2, when different from H, is attached though a carbon-carbon bond, comprising the step of reacting a compound of the formula (2): with a halogenation agent in the presence of a catalytic amount of a chiral nitrogen containing organic compound.
Stereoselective Synthesis of Chiral 4-(1-Chloroalkyl)-β-Lactams Starting from Amino Acids and Their Transformation into Functionalized Chiral Azetidines and Pyrrolidines
作者:Stijn Dekeukeleire、Matthias D’hooghe、Karl W. Törnroos、Norbert De Kimpe
DOI:10.1021/jo101220q
日期:2010.9.3
α-chlorination procedures. The latter aldehydes proved to be useful starting materials for the stereoselective Staudinger synthesis of (3S,4S)-4-[(1S)-1-chloroalkyl]azetidin-2-ones in high diastereomeric ratios and good overall yields, which were used as chiral building blocks for the preparation of a number of azetidines and pyrrolidines.