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).
Metal-free synthesis of 2-aminobenzoxazoles using hypervalent iodine reagent
作者:Yogesh S. Wagh、Neelam J. Tiwari、Bhalchandra M. Bhanage
DOI:10.1016/j.tetlet.2012.12.127
日期:2013.3
A facile, simple, mild, and metal-free protocol for the synthesis of 2-aminobenzoxazoles has been developed via C–H bond amination of benzoxazoles with amines through a ring-opening and subsequent ring-closure approach. The reaction was performed in two steps wherein nucleophilic addition of amines across benzoxazoles takes place in the absence of any reagent or catalyst under solvent-free condition