Palladium-Catalyzed Carbonylative Four-Component Synthesis of Thiochromenones: The Advantages of a Reagent Capsule.

Multicomponent reactions, especially those involving four or even more reagents, have been a long-standing challenge because of the issues associated with balancing reactivity, selectivity, and compatibility. Herein, we demonstrate how the use of a reagent capsule provides straightforward access to synthetically valuable thiochromenone derivatives by a palladium-catalyzed carbonylative four-component reaction. To the best of our knowledge, this is the first example of applying a capsule to prevent catalyst poisoning and undesired side reactions of the multicomponent reaction.