Ring-Expansion Reaction of Cyclic β-Keto Esters or α-Cyano Ketones via Conjugate Addition to Alkynyl Imines: The Synthesis of Functionalized Medium-Sized Carbocycles
The ring-expansion reaction of cyclic β-keto esters or α-cyano ketones afforded two-atom-enlarged carbocyclic products in good yields via conjugateaddition to alkynyl imines. On the other hand, the reaction of ethyl 2-oxocyclododecanecarboxylate with alkynyl imine proceeded smoothly to give bicyclo-2-pyridone in moderate yield.