Fluorinated arylborane-based Lewis acid catalysts have shown remarkable activity and serve as ideal examples of transition metal-free catalysts for diverse organic transformations. However, their homogeneous nature poses challenges in terms of recyclability and separation from reaction mixtures. This work presents an efficient technique for the heterogenization of boron Lewis acid catalysts by anchoring Piers’ borane to allyl-functionalized iron oxide. This catalyst demonstrates excellent activity in the hydrosilylation of imines and the reductive amination of carbonyls using various silanes as reducing agents under mild reaction conditions. The catalyst exhibits broad tolerance towards a wide range of functional substrates. Furthermore, it exhibits good recyclability and can be easily separated from the products using an external magnetic field. This work represents a significant advance in the development of sustainable heterogenous metal-free catalysts for organic transformations.

中文翻译：

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用于亚胺氢化硅烷化和羰基还原胺化的磁性可回收硼烷路易斯酸催化剂

氟化芳基硼烷基路易斯酸催化剂表现出显着的活性，是各种有机转化的无过渡金属催化剂的理想例子。然而，它们的均质性质在可回收性和从反应混合物中分离方面提出了挑战。这项工作提出了一种通过将 Piers 硼烷锚定到烯丙基官能化氧化铁上来实现硼路易斯酸催化剂多相化的有效技术。该催化剂在温和的反应条件下，使用各种硅烷作为还原剂，在亚胺的氢化硅烷化和羰基的还原胺化中表现出优异的活性。该催化剂对多种功能底物表现出广泛的耐受性。此外，它具有良好的可回收性，并且可以利用外部磁场轻松地与产品分离。这项工作代表了开发用于有机转化的可持续异质无金属催化剂的重大进展。