Alkylaluminum Complexes Featuring Bridged Bis-Formylfluorenimide Ligands for Hydroboration of Aldehyde, Ketone, and Imines

作者：Chaoqun Wang, Mengna Huang, Hui Miao, Chenxu Liu, Zhibiao Qin, W MA, Mengmeng Han, Junjie Yu, Yongmin Li, Biao Wei, Zheng Chen · 发表于：Inorganic Chemistry · 年份：2024 · DOI：10.1021/acs.inorgchem.4c03158 · 被引用次数：4 · 研究领域：Asymmetric Hydrogenation and Catalysis、Organoboron and organosilicon chemistry、Carbon dioxide utilization in catalysis

Three bis-formylfluorenimide ligands with different bridging groups were designed and synthesized, leading to the successful preparation of six novel alkylaluminum complexes through their reaction with alkylaluminum reagents (AlMe 3 or AlEt 3 ). Complexes 1 and 2 were obtained by the reaction of 1,2-propylene-bridged diamine ( L 1 ) with AlMe 3 or AlEt 3 . By reacting 1,2-cyclohexylene-bridged diamine ( L 2 ) with AlMe 3 or AlEt 3 to obtain complexes 3 and 4 . The above ligands formed a bidentate four-coordinate structure with alkylaluminum, which involved the elimination of one alkyl group as the ligand reacted with alkylaluminum. The complexes 5 and 6 were synthesized through the reaction of 1,2-phenylene-bridged diamine ( L 3 ) with AlEt 3 in toluene or tetrahydrofuran. Notably, L 3 exhibited unique reactivity compared with the other ligands, which formed a tridentate four-coordinated structure when reacting with alkylaluminum. The formation of the tridentate complex resulted from the introduction of a benzimidazole derivative or tetrahydrofuran (THF) molecule along with the elimination of two alkyl groups during its coordination with alkylaluminum. All complexes were characterized via 1 H NMR, 13 C NMR, and elemental analysis, with structural determination confirmed through X-ray. Furthermore, the catalytic activity in the hydroboration reaction of aldehyde, ketone, and imines was investigated with these complexes as catalysts. Among them, complex 1 demonstrated excellent...