Sustainable Synthesis of Diverse Privileged Heterocycles by Palladium-Catalyzed Aerobic Oxidative Isocyanide Insertion
作者:Tjøstil Vlaar、Razvan C. Cioc、Pieter Mampuys、Bert U. W. Maes、Romano V. A. Orru、Eelco Ruijter
DOI:10.1002/anie.201207410
日期:2012.12.21
O2 in, H2O out: Various diamines and related bisnucleophiles readily undergo oxidativeisocyanideinsertion with Pd(OAc)2 (1 mol %) as the catalyst and O2 as the terminal oxidant to give a diverse array of medicinally relevant N heterocycles. The utility of this highly sustainable method is demonstrated by a formal synthesis of the antihistamines astemizole and norastemizole.
O 2 in,H 2 O out:各种二胺和相关的双亲核试剂易于经历氧化异氰化物的插入,其中Pd(OAc)2(1 mol%)作为催化剂,O 2作为末端氧化剂,可得到多种与医学相关的N杂环。抗组胺药阿司咪唑和去甲阿司咪唑的正式合成证明了这种高度可持续性方法的实用性。
Synthesis of Diverse Nitrogen Heterocycles <i>via</i>
Palladium-Catalyzed Tandem Azide-Isocyanide Cross-Coupling/Cyclization: Mechanistic Insight using Experimental and Theoretical Studies
作者:Arshad J. Ansari、Ramdas S. Pathare、Antim K. Maurya、Vijai K. Agnihotri、Shahnawaz Khan、Tapta Kanchan Roy、Devesh M. Sawant、Ram T. Pardasani
DOI:10.1002/adsc.201700928
日期:2018.1.17
A rapid and elegant tandem azide–isocyanide cross‐coupling/cyclization protocol has been developed based on a nitrene transfer reaction. The palladium‐catalyzed ligand‐free methodology led to the synthesis of three different heterocyclic scaffolds with excellent atom/step/redox economy. Studies based on first‐principles‐based quantum calculations and control experiments unraveled a concerted process
A new iron-catalyzed, direct C-H amination of azoles at C2 has been developed by usingformamides or amines as nitrogen sources. Imidazole is the only additive in the catalyst system and oxygen in air is employed during the transformation process.
This protocol describes a novel, mild and convenient route to afford 2-aminobenzoxazoles in high yields, and represents a significant advance towards an environmentally friendly strategy. Aliphatic amines are made to react with carbon disulfide to provide intermediate dithiocarbamates (DTC), which in the presence of 2-aminophenol, subsequently undergo successive intermolecular nucleophilic attack and desulfurization to produce 2-aminobenzoxazoles within 3 h.
An efficient synthesis of 2-aminobenzoxazoles is described by a direct oxidative amination of unfunctionalized benzoxazoles with primary amines. The reaction could be performed in the absence of transition metals by using catalytic amounts of a quaternary ammonium iodide and tert-butylhydroperoxide as a cheap and easy-to-handle co-oxidant. In addition to primary amines, aqueous solutions of NH3 were used to introduce a primary amine group into the heterocyclic core.