Quadri‐Synergetic Effect for Highly Effective Carbon Dioxide Fixation and Its Application to Indoloquinolinone

Abstract The first copper‐catalyzed cyclic anti ‐nucleometallation–carboxylation of 2‐alkynylanilines with carbon dioxide in the presence of dimethylzinc (ZnMe 2 ) and cesium fluoride (CsF) for the effective synthesis of indolyl‐3‐carboxylic acids and indolodihydropyran‐2‐one is described. Through a mechanistic study, it is unveiled that the metal ions Cu 2+ , Zn 2+ , Cs + and F − are working together for this CO 2 ‐based highly efficient carboxylation.