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

ABSTRACT

The cooperative Lewis and Brønsted acid catalysis makes convergent synthesis of 3(2H)-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.