Consecutive multi-component syntheses of heterocycles via palladium-copper catalyzed generation of alkynones

Alkynones are prominent three-carbon building blocks in heterocyclic chemistry. They can be generated very easily and efficiently by modified Sonogashira coupling of acid chlorides and terminal alkynes. Mild reaction conditions now set the stage for new diversity-oriented routes to heterocycles by sequential and consecutive transformations. Hence, isoxazoles, indolizines, pyrazoles, pyridimines, 1,5-benzoheteroazepines, furans, oxazoles, and tetrahydro-beta-carbolines are accessible by consecutive coupling-cycloaddition or coupling-addition-cyclocondensation multi-component sequences.