Gold-catalyzed three-component tandem process: an efficient and facile assembly of complex butenolides from alkynes, amines, and glyoxylic acid.

An efficient and facile gold-catalyzed three-component tandem process for the assembly of two types of highly functionalized butenolides has been developed. In this reaction system, more than four chemical bonds are formed by a single gold catalyst. The present tandem protocol includes a direct coupling of alkynes, amines, and glyoxylic acid and subsequent exclusively endo-selective cycloisomerization of alkynoic acids along with intermolecular electrophilic trapping; it utilizes three simple and commercially available starting materials to assemble architecturally complex and appealing butenolide scaffolds bearing other reactive sites for further manipulation.