Cesium Carbonate-Promoted Hydroamidation of Alkynes: Enamides, Indoles and the Effect of Iron(III) Chloride

A series of enamide derivatives was prepared by a simple procedure for the hydroamidation of alkynes with amides and sulfonamides. The use of such a mild base as cesium carbonate promotes the latter transformation, and the addition of catalytic amounts of iron(III) chloride has a beneficial effect in the outcome of some of the presented hydroamidation reactions. A range of indoles was also synthesized from ortho-alkynylanilides by both complementary procedures, which proved to be useful for the construction of the indolo[1,2-c]quinazoline tetracyclic system from an ortho-(2-aminophenylalkynyl)anilide.