Rh-Catalyzed Ortho-Selective C–H Borylation of N-Functionalized Arenes with Silica-Supported Bridgehead Monophosphine Ligands
摘要:
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.
Iridium-Catalyzed, Substrate-Directed C–H Borylation Reactions of Benzylic Amines
作者:Andrew J. Roering、Lillian V. A. Hale、Phillip A. Squier、Marissa A. Ringgold、Emily R. Wiederspan、Timothy B. Clark
DOI:10.1021/ol301635x
日期:2012.7.6
The iridium-catalyzedarene C–H borylation reaction of benzylic amines has been developed, which inverts the typical steric-controlled product distribution to provide ortho-substituted boronate esters. Picolylamine was found to be an ideal ligand to replace 4,4′-di-tert-butylbipyridine to induce the directing effect. Preliminary experiments are consistent with a mechanism involving dissociation of
Synthesis of Biaryl Ethers by the Copper-Catalyzed Chan–Evans–Lam Etherification from Benzylic Amine Boronate Esters
作者:Justin S. Marcum、Kathryn A. McGarry、Carl J. Ferber、Timothy B. Clark
DOI:10.1021/acs.joc.6b01254
日期:2016.9.2
benzylic amines with phenols has been achieved to provide biaryl ethers that are prevalent in biologically active compounds. A variety of substitution patterns on the aryl boronate ester and the phenol are tolerated under the reaction conditions, providing moderate to high yields. A competition reaction between phenol and aniline revealed condition-dependent selectivity in which the phenol could be highly
Role of Hemilabile Diamine Ligands in the Amine-Directed C–H Borylation of Arenes
作者:Lillian V. A. Hale、Kathryn A. McGarry、Marissa A. Ringgold、Timothy B. Clark
DOI:10.1021/om5007837
日期:2015.1.12
A study of the role played by the bidentate ligand used in amine-directed CH borylation is described. Both reaction conversion and selectivity were significantly impacted when steric congestion and electronic perturbations of the bidentate diamine ligand were made, but a more significant influence was imparted by reducing the bite angle of the ligand. N-Benzylaminopyridine was identified as a general ligand that improves both selectivity and yield for most problematic substrates previously reported with picolylamine as ligand.
Selective Formation of <i>ortho</i>-Aminobenzylamines by the Copper-Catalyzed Amination of Benzylamine Boronate Esters
作者:Kathryn A. McGarry、Alexi A. Duenas、Timothy B. Clark
DOI:10.1021/acs.joc.5b01074
日期:2015.7.17
The copper-catalyzedcoupling between benzylamino boronate esters and aryl amines has been investigated. Formation of ortho-aminobenzylamines was achieved under oxidative conditions in the presence of copper(II) acetate. The major side product of the transformation is the homocoupling of the aryl boronate ester. The formation of the desired diamines was found to be improved in the absence of base,
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.