Synthesis, evaluation and application of novel bifunctional N,N-di-isopropylbenzylamineboronic acid catalysts for direct amide formation between carboxylic acids and amines
Synthesis, evaluation and application of novel bifunctional N,N-di-isopropylbenzylamineboronic acid catalysts for direct amide formation between carboxylic acids and amines
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DOI：
10.1039/b712008g
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发表时间：
2008-01-01
期刊：
影响因子：
9.8
通讯作者：
Whiting, Andrew
中科院分区：
文献类型：
--
作者：
Arnold, Kenny;Batsanov, Andrei S.;Whiting, Andrew
通过定向金属化-硼化反应合成了3-氟、3-甲氧基和5-三氟甲基N，N-二异丙基苄胺-2-硼酸衍生物。吸电子基团的加入确实增加了这种体系的反应性，以在迄今为止所采用的大多数环境条件下充当改进的直接酰胺形成催化剂。相反，给电子基团确实导致催化剂反应性的显著降低。DoE研究已用于确定应使用这些类型的催化剂的理想反应条件，典型的是母体系统N，N-二异丙基苄胺-2-硼酸。这在5摩尔%负载量和更高稀释条件下显示出最佳性能，这最可能反映了溶剂的干燥能力。
Three new derivatives of N,N-di-isopropylbenzylamine-2-boronic acid have been prepared by directed metallation-borylation methods, to derive the 3-fluoro, 3-methoxy and 5-trifluoromethyl systems. The addition of an electron withdrawing group does increase the reactivity of such systems to act as improved direct amide formation catalysts under the most ambient conditions employed to date. In contrast, an electron donating group does result in considerable lowering of catalyst reactivity. DoE studies have been used to identify the ideal reaction conditions under which these types of catalysts should be used, typified by the parent system N,N-di-isopropylbenzylamine-2-boronic acid. This shows best performance at a 5 mol% loading and under higher dilution conditions, which most likely reflect the drying capacity of the solvent.