Efficient Cobalt Catalyst for Ambient-Temperature Nitrile Dihydroboration, the Elucidation of a Chelate-Assisted Borylation Mechanism, and a New Synthetic Route to Amides
作者:Chandrani Ghosh、Suyeon Kim、Matthew R. Mena、Jun-Hyeong Kim、Raja Pal、Christopher L. Rock、Thomas L. Groy、Mu-Hyun Baik、Ryan J. Trovitch
DOI:10.1021/jacs.9b07529
日期:2019.9.25
arm to regenerate (κ4-N,N,N,N-PyEtIPCHMeNEtPy)Co. Borylimine reduction is in turn facile and follows the same ligand-assisted borylation pathway. The independent hydroboration of alkyl and aryl imines was also demonstrated at 25 °C. With a series of N,N-diborylamines in hand, their addition to carboxylic acids allowed for the direct synthesis of amides at 120 °C, without the need for exogenous coupling
N,N-二硼胺已成为有机合成中很有前途的试剂。然而,它们的高效制备和全合成效用尚未实现。为了解决这两个缺点,寻求用于腈二氢硼化的有效催化剂。在 PyEtPDI 存在下加热 CoCl2,得到六配位 Co(II) 盐,[(PyEtPDI)CoCl][Cl]。添加 2 当量的 NaEt3BH 后,观察到氢化物转移到一个螯合亚胺官能团,导致形成 (κ4-N,N,N,N-PyEtIPCHMeNEtPy)Co。单晶 X 射线衍射和密度泛函理论计算表明,该化合物具有低自旋 Co(II) 基态,其特征是与单个还原的亚氨基(吡啶)部分具有反铁磁耦合。重要的是,(κ4-N,N,N, 发现 N-PyEtIPCHMeNEtPy)Co 使用 HBPin 催化腈的二氢硼化反应,在环境温度下的周转频率高达 380 h-1。化学计量加成实验表明,HBPin 通过 Co-Namide 键加成生成可与额外的 HBPin 或腈