Facile synthesis of 2-alkynyl oxazoles via a Ce(OTf)3-catalyzed cascade reaction of alkynyl carboxylic acids with tert-butyl isocyanide.

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 exhibited good anticancer activities in human gastric cancer cells (MGC803) and human bladder tumor cells (T24), with IC50 below 20.0 μM.