Tandem reversible addition–intramolecular lactonization for the synthesis of 3-functionalized phthalides

A new tandem process based on reversible nucleophilic addition and intramolecular lactonization of methyl 2-formylbenzoate leads to the efficient synthesis of 3-functionalized phthalides, which are important precursors for the synthesis of quinone skeletons via Hauser–Kraus annulation. The reactions are successfully carried out under mild conditions in single operations.