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La[N(SiMe3)2]3 – Catalyzed Deoxygenative Reduction of Amides with Pinacolborane. Scope and Mechanism
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2020-04-06 , DOI: 10.1021/jacs.0c02446
Christopher J Barger 1 , Rachel D Dicken 1 , Victoria L Weidner 1 , Alessandro Motta 2 , Tracy L Lohr 1 , Tobin J Marks 1
Affiliation  

Tris[N,N-bis(trimethylsilyl)amide]lanthanum (LaNTMS) is an efficient and selective homogeneous catalyst for the deoxygenative reduction of tertiary and secondary amides with pinacolborane (HBpin) at mild temperatures (25-60 °C). The reaction, which yields amines and O(Bpin)2, tolerates nitro, halide, and amino functional groups well, and this amide reduction is completely selective for both inter- and intramolecular alkene/alkyne hydroboration. Kinetic studies indicate that amide reduction obeys an unusual mixed-order rate law which is proposed to originate from saturation of the catalyst complex with HBpin. Kinetic and thermodynamic studies, isotopic labeling, and DFT calculations using energetic span analysis suggest the role of a [(Me3Si)2N]2La-OCHR(NR'2)[HBpin] active catalyst, and hydride transfer is proposed to be ligand-centered. These results add to the growing list of transformations that commercially-available LaNTMS is competent to catalyze, further underscoring the value and versatility of lanthanide complexes in homogeneous catalysis.

中文翻译:

La[N(SiMe3)2]3 – 用频哪硼烷催化酰胺脱氧还原。范围和机制

Tris[N,N-双(三甲基甲硅烷基)酰胺]镧 (LaNTMS) 是一种高效且选择性的均相催化剂,用于在温和温度 (25-60 °C) 下用频哪醇硼烷 (HBpin) 对叔酰胺和仲酰胺进行脱氧还原。产生胺和 O(Bpin)2 的反应很好地耐受硝基、卤化物和氨基官能团,并且这种酰胺还原对于分子间和分子内烯烃/炔烃硼氢化反应是完全选择性的。动力学研究表明,酰胺还原遵循一种不寻常的混合级速率定律,该定律被认为源于催化剂配合物与 HBpin 的饱和。动力学和热力学研究、同位素标记和使用能量跨度分析的 DFT 计算表明 [(Me3Si)2N]2La-OCHR(NR'2)[HBpin] 活性催化剂的作用,并且氢化物转移被认为是以配体为中心的.
更新日期:2020-04-06
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