Palladium‐Catalyzed Carbonylation of Multifunctionalized Substituted Alkynes to Quinolinone Derivatives under Mild Conditions

A highly selective palladium-catalyzed carbonylation of 2-alkynylanilines bearing an amide moiety to condensed six-membered heterocyclic structures has been developed under mild conditions (room temperature and atmospheric pressure of CO). The carbonylative protocol is also compatible with CO surrogates, such as benzene-1,3,5-triyl triformate (TFBen) or the newly developed calix[6]arenes functionalized with six formate groups (CLX[6]CO), which are both capable to release CO in situ. A series of tricyclic fused heterocycles containing the important oxazino-quinolinone scaffold have been selectively obtained (only the 6-endo-dig cyclization mode has been observed) in good to excellent yields (up to 99%).