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).
Visible-light-initiated photo-oxidative cyclization of phenolic amidines using CBr4 – A metal free approach to 2-aminobenzoxazoles
作者:Twinkle Keshari、Vishnu P. Srivastava、Lal Dhar S. Yadav
DOI:10.1039/c3ra46314a
日期:——
A mild and efficient one-pot operation for the amination of benzoxazoles has been achieved via ring opening of benzoxazoles followed by visible-light-mediated aerobic photo-oxidative cyclization of the resulting o-phenolic amidines using CBr4 as a mild oxidant. The protocol is economical and environmentally benign as it utilizes visible light and does not require any photosensitizers, additives, heating