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.
Copper-Catalyzed Direct Amination of Benzoxazoles Using Primary Amines as Nitrogen Sources
作者:Chun Cai、Jian Gu
DOI:10.1055/s-0034-1379886
日期:——
A facile, efficient, and simple protocol for direct oxidative C–H amination of benzoxazoles with primary amines through copper-catalyzedC–H bond activation using tert -butyl peroxide (TBP) as oxidant under air has been developed. The reaction proceeds smoothly at ambient temperature to furnish the products. A variety of substituted aminobenzoxazoles were synthesized with good to excellent yields.
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.
practical protocol for the one-pot synthesis of N-substituted 2-aminoazole derivatives is described, employing simple azole substrates, nitrogen nucleophiles, lithium tert-butoxide as the base, and iodine to mediate carbon–nitrogen bond formation. This method proceeds at room temperature under an air atmosphere using a normal benchtop set-up, or can be performed conveniently using microwave irradiation.