Facile Synthesis of 2-Alkynyloxazoles via Ce(OTf)3-Catalyzed Cascade Reaction of Alkynyl Carboxylic Acids with tert-Butyl Isocyanide

We developed an efficient and novel protocol to synthesize 2-alkynyloxazoles 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 showed a certain degree of biological activity. Moreover, the compounds 2b, 2h, 2k, 2n, 2p and 2t exhibited good anticancer activities in human gastric cancer cell (MGC803), human bladder tumor cell (T24), with IC50 below 20.0 μM.