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.