Multicomponent Synthesis of 3(2H)‐Furanones Initiated by Copper(II)‐Catalyzed Alkyne‐Carbonyl Cross Metathesis

The cooperative Lewis and Brønsted acid catalysis makes convergent synthesis of 3(2 H )‐furanones through a three‐component coupling of 1,3‐diynes, alkyl glyoxylates and water. Control experiments support that Lewis acid‐catalyzed highly chemo‐, regio‐ and stereoselective alkyne‐carbonyl metathesis of 1,3‐diynes and alkyl glyoxylates might be the initial step of this multicomponent annulation. Further chemo‐ and regioselective hydration of the alkyne‐carbonyl metathesis product and subsequent oxa‐Michael addition promoted by Brønsted acid results in the formation of two C−O bonds of the five‐membered oxygen heterocycle.