Chiral <i>C</i><sub>2</sub>-Symmetric Ligands with 1,4-Dioxane Backbone Derived from Tartrates: Syntheses and Applications in Asymmetric Hydrogenation
作者:Wenge Li、Jason P. Waldkirch、Xumu Zhang
DOI:10.1021/jo020250t
日期:2002.11.1
Chiral 1,4-diphenylphosphines 5-7 as well as thioether 8 were synthesized from tartrates employing Ley's "BDA" and "Dispoke" methodologies as the key step. Rhodium(I) complexes with 5-7 are efficient catalysts for the asymmetrichydrogenation of beta-substituted enamides and MOM-protected beta-hydroxyl enamides, which furnished chiral amines or beta-amino alcohols with 94-->99% ee. These results indicated
Development of DIOP derivatives as efficient ligands for asymmetric hydrogenation: factors controlling the reactivities and enantioselectivities
作者:Duan Liu、Wenge Li、Xumu Zhang
DOI:10.1016/j.tetasy.2004.05.042
日期:2004.7
Several DIOP derivatives have been developed as efficient ligands for Rh and Ir-catalyzed asymmetric hydrogenations. The conformational mobility of the backbone in this type of ligand plays an important role in governing both the reactivity and enantioselectivity. Isolation of pure pre-catalyst is another key factor to obtain high catalytic activity. (C) 2004 Published by Elsevier Ltd.