Alkali-Metal Promoted Chemo- and Regioselective Cycloisomerization Reactions to (Z)-3-Alkylideneisoindolin-1-ones: Unusual Positive Role of H2O

An alkali-metal promoted cycloisomerization reaction of 2-alkynylbenzamides is described for the synthesis of useful (Z)-3-alkylideneisoindolin-1-one derivatives in modest to good yields and excellent chemo- and regioselectivity. Superstoichiometric amounts of water was found to be crucial for this reaction, and no transition-metal salts are necessary. This synthetically green protocol proceeds efficiently with 100% atom economy and tolerates a diverse number of functional groups.