NewC2- andC1-Symmetric Phosphorus Ligands Based on Carbohydrate Scaffolds and Their Use in the Iridium-Catalysed Hydrogenation of Ketimines
作者:Ester Guiu、Mohamed Aghmiz、Yolanda Díaz、Carmen Claver、Benjamí Meseguer、Christian Militzer、Sergio Castillón
DOI:10.1002/ejoc.200500523
日期:2006.2
as catalyst. These ligands were added to iridium complexes to give catalyst precursors that are active in the hydrogenation of imines 17 and 19. Cationic iridium complexes gave rise to catalytic systems that were more active than the neutral iridium complexes. The use of additives was, in general, detrimental to both the conversion and the enantioselectivity. In the hydrogenation of 17, results were
C2 对称二亚膦酸酯配体 10a-d,在芳基中具有不同的给电子或吸电子基团,以及 C1 对称亚膦酸酯 - 亚磷酸酯配体 11a,b,直接由葡糖胺制备。探索了合成次膦酸酯官能团的各种程序以提高反应的产率。当 Ph2PNEt2 在四唑作为催化剂的存在下使用时,结果最好。将这些配体添加到铱络合物中以产生在亚胺 17 和 19 的氢化中具有活性的催化剂前体。阳离子铱络合物产生比中性铱络合物更具活性的催化体系。通常,添加剂的使用对转化率和对映选择性都是有害的。在 17 的氢化中,配体 11a(76 % ee)的结果最好,但在 19 (70 % ee) 的氢化中,配体 10b 效果最好。(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)