作者:José A. Fernández-Salas、Simone Manzini、Lorenzo Piola、Alexandra M. Z. Slawin、Steven P. Nolan
DOI:10.1039/c4cc02096k
日期:——
An easily prepared series of phenylindenyldihydridosilyl ruthenium complexes (2aâ2d) was obtained by reaction of tertiary silanes with the commercially-available [RuCl(3-phenylindenyl)(PPh3)2] (1). The [RuH2(3-phenylindenyl)(SiEt3)] (2a) complex was shown to be highly efficient (1.5 mol%) in the ortho-selective borylation of pyridyl substrates, with yields of up to 90%. A novel ruthenium(IV)-catalysed CâH activation borylation/functionalization reaction using a remarkably low catalyst loadings is described.
Supported phosphine-Rh systems, prepared in situ from silica-supported bridgehead monophosphines and [Rh(OH)(cod)]2, have enabled ortho-selective C-H borylation for a range of arenes containing nitrogen-based directing groups. The regioselectivity was excellent with various N-directing groups, including saturated and unsaturated N-heterocycles, tert-aminoalkyl groups, and iminetype C-N double bonds. The reaction showed significant tolerance toward steric repulsion around the reacting C-H bond. This Rh catalysis complements the Jr-catalyzed orthoborylation, which is effective for arenes with oxygen-based directing groups.
N-heterocyclic carbene enabled rhodium-catalyzed ortho C(sp2)-H borylation at room temperature
作者:Lei Zhong、Zhi-Hong Zong、Xi-Cun Wang
DOI:10.1016/j.tet.2019.03.033
日期:2019.4
We report a rhodium-catalyzed ortho C(sp2)-H borylation of 2-phenylpyridines using commercially available N-heterocyclic carbenes (NHCs) as ligand and pinacolatodiboron (B2pin2) as borylating reagent. The reaction could take place at roomtemperature, tolerating a wide range of functionalities and affording ortho borylated products in moderate to excellent yields. The current method is also applicable