A family of N-heterocyclic carbene-stabilized borenium ions for metal-free imine hydrogenation catalysis
作者:Jeffrey M. Farrell、Roy T. Posaratnanathan、Douglas W. Stephan
DOI:10.1039/c4sc03675a
日期:——
This manuscript probes the steric and electronic attributes that lead to “frustrated Lewis pair” (FLP)-type catalysis of imine hydrogenation by borenium ions. Hydride abstraction from (ItBu)HB(C6F5)22 prompts intramolecular C–H bond activation to give (CHN)2(tBu) (CMe2CH2)CB(C6F5)23, defining an upper limit of Lewis acidity for FLP hydrogenation catalysis. A series of seven N-heterocyclic carbene–borane
这份手稿探讨了导致硼离子对亚胺加氢的“受挫路易斯对”(FLP) 型催化的空间和电子属性。从 (I t Bu)HB(C 6 F 5 ) 2 2中提取的氢化物促使分子内 C-H 键活化得到 (CHN) 2 ( t Bu) (CMe 2 CH 2 )CB(C 6 F 5 ) 2 3,定义了 FLP 加氢催化的路易斯酸度上限。一系列七种 N-杂环卡宾-硼烷 (NHC-硼烷) 加合物 ((R'CNR) 2 C)(HBC 8 H 14) (R' = H, R = dipp 4a , Mes 5a , Me 8a ; R = Me R' = Me 9a , Cl, 10a ) 和 ((HC) 2 (NMe)(NR)C)(HBC 8 H 14 ) (R = t Bu, 6a , Ph 7a ) 被制备并转化为相应的硼鎓盐。这些物质被评估为室温下无金属亚胺氢化的催化剂。用于原型底物N-亚苄基-叔氢化的卡宾供