Efficient Regioselective Preparationof Monobromo and Bromoiodo Hydroxy Pyridines from Dibromoderivativesvia Bromine-Lithium Exchange
作者:Mª Ascensión Sanz-Tejedor、Ángela Meana、Justo F. Rodríguez、José L. García-Ruano
DOI:10.1055/s-2003-41013
日期:——
Annular dibromination of hydroxypyridines with NBS in acetonitrilefollowed by bromine-lithium exchange with RLi and subsequent trappingwith H2O or I2 afforded monobromo and bromoiododerivatives in a completely regioselective way. Iodination of bromohydroxypyridines with NIS is totally regioselective.
Metal-Free Decarboxylative Hetero-Diels–Alder Synthesis of 3-Hydroxypyridines: A Rapid Access to <i>N</i>-Fused Bicyclic Hydroxypiperidine Scaffolds
作者:Laurie-Anne Jouanno、Vincent Di Mascio、Vincent Tognetti、Laurent Joubert、Cyrille Sabot、Pierre-Yves Renard
DOI:10.1021/jo402729a
日期:2014.2.7
A complete experimental and theoreticalstudy of the thermally controlled metal-free decarboxylative hetero-Diels–Alder (HDA) reaction of 5-alkoxyoxazoles with acrylic acid is reported. This strategy offers a new entry to valuable 2,6-difunctionalized 3-hydroxypyridines from readily available 2- and 4-disubstituted 5-alkoxyoxazoles. The reaction conditions proved compatible with, among others, ketone