From 4,5,6,7-tetrahydroindoles to 3- or 5-(4,5,6,7-tetrahydroindol-2-yl)isoxazoles in two steps: a regioselective switch between 3- and 5-isomers
作者:Lyubov N. Sobenina、Denis N. Tomilin、Maxim D. Gotsko、Igor A. Ushakov、Albina I. Mikhaleva、Boris A. Trofimov
DOI:10.1016/j.tet.2014.05.099
日期:2014.8
(4,5,6,7-Tetrahydroindo1-2-yl]alkynes, synthesized by cross-coupling of 4,5,6,7-tetrahydroindoles with aroyl(hetaroyl)bromoallcynes or ethyl bromopropynoate in the presence of K2CO3, regioselectively cyclize with hydroxylamine to either 3- or 5-(4,5,6,7-tetrahydroindol-2-yl)isoxazoles depending on the acidity of the reaction mixture: in the presence of acetic acid 3-isomers are formed (ca. 100% selectivity), while under neutral conditions the reaction is switched to 5-isomers (94-97% selectivity). (C) 2014 Published by Elsevier Ltd.