Catalytic <i>Syn</i>-Selective Nitroaldol Approach to Amphenicol Antibiotics: Evolution of a Unified Asymmetric Synthesis of (−)-Chloramphenicol, (−)-Azidamphenicol, (+)-Thiamphenicol, and (+)-Florfenicol
diastereo- and enantioselective synthesis of (−)-chloramphenicol, (−)-azidamphenicol, (+)-thiamphenicol, and (+)-florfenicol based on a key catalytic syn-selective Henryreaction is reported. The stereochemistry of the ligand-enabled copper(II)-catalyzed aryl aldehyde Henryreaction of nitroethanol was first explored to forge a challenging syn-2-amino-1,3-diol structure unit with vicinal stereocenters
报告了基于关键催化顺选择性亨利反应高效和高非对映选择性和对映选择性合成 (-)-氯霉素、(-)-阿齐丹苯、(+)-噻吩苯胺和 (+)-氟苯尼考的统一策略. 首次探索了配体启用的铜 (II) 催化的硝基乙醇的芳醛亨利反应的立体化学,以形成具有挑战性的合成-2-氨基-1,3-二醇结构单元,具有具有出色立体控制的邻位立体中心。进行了多步连续流动操作以实现该家族的双酚类抗生素的有效不对称合成。
Chiral Cyclopentadienyl-Iron and -Ruthenium Lewis Acids Containing the Electron-Poor BIPHOP-F Ligand: a Comparison as Catalysts in an Asymmetric Diels-Alder Reaction
作者:E. Peter Kündig、Christophe M. Saudan、Florian Viton
Chiral iron and ruthenium Lewisacids: analogies and differences between the catalysts and the role of the anion in catalytic Diels-Alder reaction. In short: Fe catalysts are faster but Ru analogues are more stable and can be recovered quantitatively. Rational ligand design is shown to result in a large increase in chiral induction.
Catalytic Enantioselective and Catalyst-Controlled Diastereofacial-Selective Additions of Allyl- and Crotylboronates to Aldehydes Using Chiral Brønsted Acids
作者:Vivek Rauniyar、Dennis G. Hall
DOI:10.1002/anie.200504432
日期:2006.4.3
Oxazaborolidine-mediated asymmetric reduction of 1,2-diaryl-2-benzyloxyiminoethanones and 1,2-diarylethanediones
Highly enantioselective reduction of 1,2-diaryl-2-benzyloxyiminoethanones and 1,2-diarylethanediones was conducted using oxazaborolidine derived from L-threonine and borane complexes to give B-imino alcohols and 1,2-diaryl-1,2-ethanediols in high enantiomeric purity. Subsequent reduction of the imino functionality of the former products afforded either syn- or anti-2-amino-1,2-diarylethanols in high enantiomeric purity by choosing appropriate reduction methods. (C) 1998 Elsevier Science Ltd. All rights reserved.