Dichotomous control of E/Z-geometry in intramolecular cyclization of o-alkynylbenzamide derivatives catalyzed by organic superbase P4-tBu in the presence/absence of water

E/Z does it! An intramolecular cycli-zation reaction of o-alkynylbenzamides that allows dichotomous control of E/Z-geometry has been developed using an organic superbase, P4-tBu, as a catalyst. The presence/absence of water along with the use of an organic superbase provides the necessary control of the geometry at the exo-double bond. The method enables efficient access to isoindolinone derivatives, an important class of biologically active molecules.