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%).