Ru-catalyzed decarboxylative annulations of α-keto acids with internal alkynes: dual roles of COOH as directing group and leaving group.

Carboxylic acid serving as both directing and leaving group was discovered in Ru-catalyzed decarboxylative annulations of α-keto acids with alkynes. The well-established protocol showed high functional group tolerance, which provided an efficient and alternative route to the coumarone backbone.