Consecutive Gold(I)-Catalyzed Cyclization Reactions of o‑(Buta-1,3-diyn-1-yl-)-Substituted N‑Aryl Ureas: A One-Pot Synthesis of Pyrimido[1,6‑a]indol-1(2H)‑ones and Related Systems

Treatment of readily available o-(buta-1,3-diyn-1-yl-)-substituted N-aryl ureas such as 1 with the Au(I)-catalyst 11 affords, via a twofold cyclization process, the isomeric pyrimido[1,6-a]indol-1(2H)-one 3 in good yield.