underwent co‐trimerization with carboxylic acids in the presence of ZnBr2 to smoothly provide oxazoles (see scheme). The reaction is thought to occur by initial nucleophilic addition of the carboxylic acid to a ligated isonitrile molecule, followed by a sequence involving double migratory insertion, metal‐salt elimination, acyl migration, cyclization, and dealkylation.
Facile synthesis of 2-alkynyl oxazoles <i>via</i> a Ce(OTf)<sub>3</sub>-catalyzed cascade reaction of alkynyl carboxylic acids with <i>tert</i>-butyl isocyanide
作者:Ming Cao、Qing-Hu Teng、Zhi-Wei Xi、Li-Qiu Liu、Ren-Yong Gu、Ying-Chun Wang
DOI:10.1039/c9ob02337b
日期:——
We developed an efficient and novel protocol to synthesize 2-alkynyl oxazoles from tert-butyl isocyanide and alkynyl carboxylic acids. This method allowed the synthesis of diversely functionalized oxazoles under mild reaction conditions, coupled with operational simplicity and these functionalized oxazoles showed a certain degree of biological activity. Moreover, compounds 2b, 2h, 2k, 2n, 2p and 2t