β-Amino alcohols derived from (1R,2S)-norephedrine and (1S,2S)-pseudonorephedrine as catalysts in the asymmetric addition of diethylzinc to aldehydes
摘要:
A family of N-alkylnorephedrine and N-alkylpseudonorephedrine derived ligands were prepared and applied in the asymmetric alkylation of benzaldehyde using diethylzinc. The absolute configuration of the addition product was directed primarily by the benzylic position of the Ephedra alkaloid, while the magnitude of the enantiomeric ratio was heavily influenced by the nitrogen substituent. However, sterically demanding substituents at the nitrogen position caused the enantioselectivity to be the same for the two diastereomeric systems. Among the ligands that were prepared, it was determined that the N-cyclooctylpseudonorephedrine derivative 7b yielded the highest enantiomeric ratios (87.5:12.5 to 91.0:9.0) when applied in the catalytic asymmetric addition of diethylzinc to aldehydes. (c) 2007 Elsevier Ltd. All rights reserved.
Design of a Genetic Algorithm for the Simulated Evolution of a Library of Asymmetric Transfer Hydrogenation Catalysts
作者:Nicolas Vriamont、Bernadette Govaerts、Pierre Grenouillet、Claude de Bellefon、Olivier Riant
DOI:10.1002/chem.200802192
日期:2009.6.15
Breeding newcatalysts: A library of 1980 catalysts was designed for asymmetrichydrogentransfer to acetophenone. The library was submitted to evaluation and further simulated evolution experiments, based on a genetic algorithm (see scheme). We demonstrated that it was easily possible to get 5–6 of the ten best catalysts, while investigating only 10% of the library.
β-Amino alcohols derived from (1R,2S)-norephedrine and (1S,2S)-pseudonorephedrine as catalysts in the asymmetric addition of diethylzinc to aldehydes
作者:Raleigh W. Parrott、Shawn R. Hitchcock
DOI:10.1016/j.tetasy.2007.11.027
日期:2008.1
A family of N-alkylnorephedrine and N-alkylpseudonorephedrine derived ligands were prepared and applied in the asymmetric alkylation of benzaldehyde using diethylzinc. The absolute configuration of the addition product was directed primarily by the benzylic position of the Ephedra alkaloid, while the magnitude of the enantiomeric ratio was heavily influenced by the nitrogen substituent. However, sterically demanding substituents at the nitrogen position caused the enantioselectivity to be the same for the two diastereomeric systems. Among the ligands that were prepared, it was determined that the N-cyclooctylpseudonorephedrine derivative 7b yielded the highest enantiomeric ratios (87.5:12.5 to 91.0:9.0) when applied in the catalytic asymmetric addition of diethylzinc to aldehydes. (c) 2007 Elsevier Ltd. All rights reserved.