Amination of Benzoxazoles and 1,3,4-Oxadiazoles Using 2,2,6,6-Tetramethylpiperidine-N-oxoammonium Tetrafluoroborate as an Organic Oxidant
作者:Sebastian Wertz、Shintaro Kodama、Armido Studer
DOI:10.1002/anie.201104735
日期:2011.11.25
No transition metals are necessary to convert benzoxazoles and 1,3,4‐oxadiazoles into the corresponding pharmacologically interesting 2‐aminated heterocycles by formal direct C(2)‐aminationusing tetramethylpiperidine‐N‐oxoammonium tetrafluoroborate (TEMPO+BF4−) as an oxidant (see scheme; TEMP=2,2,6,6‐tetramethylpiperidine; TfOH=trifluoromethanesulfonic acid).
A Metal-Free Route to 2-Aminooxazoles by Taking Advantage of the Unique Ring Opening of Benzoxazoles and Oxadiazoles with Secondary Amines
作者:Jomy Joseph、Ji Young Kim、Sukbok Chang
DOI:10.1002/chem.201100910
日期:2011.7.18
Toss an amine into the ring: A new metal‐free protocol for the amination of oxazoles has been developed by using iodobenzene diacetate to couple various oxazoles with amines (see scheme). The reaction proceeds through a ring‐opening and subsequent ring‐closing pathway. The optimal conditions are very mild and the substrate scope is broad, producing a range of 2‐aminooxazoles, an important pharmacophore
Dioxygen-triggered oxidative cleavage of the C–S bond towards C–N bond formation
作者:Zongchao Lv、Huamin Wang、Zhicong Quan、Yuan Gao、Aiwen Lei
DOI:10.1039/c9cc05707b
日期:——
Research on the cleavage of C–C bonds has been well developed. By comparison with this, the activation of C–S bonds remains challenging. Herein, dioxygen-triggered oxidative cleavage of C–S bonds has been achieved, delivering a series of N-containing heterocyclic compounds that are frequently found in pesticides and pharmaceuticals. Additionally, the potential utility of this protocol was further demonstrated
Chloroamine serves as an efficient amination reagent to the heteroaromatic C-H bond of azole under copper catalysis even at room temperature. This catalysis enables a rapid and concise construction of aminoazoles of great interest in biological and medicinal chemistry.
Synthesis of 2-aminobenzoxazoles via copper-catalyzed electrophilic amination of benzoxazoles with O-benzoyl hydroxylamines
An efficient copper-catalyzed electrophilic amination of benzoxazoles with O-benzoyl hydroxylamines is described, employing CuCl catalyst, PPh3 ligand, and (LiOBu)-Bu-t base. This simple air-stable copper catalysis enables the preparation of various 2-aminobenzoxazole derivatives at room temperature in good yields. (C) 2013 Elsevier Ltd. All rights reserved.