Aza-Diels-Alder reaction of both electron-deficient azoalkenes with electron-deficient 3-phencaylideneoxindoles and 3-aryliminooxindol-2-ones

Abstract

An uncommon aza-Diels-Alder reaction of electron-deficient azoalkenes and electron-deficient 3-phenacylideneoxindoles was successfully developed for convenient construction of the heterocyclic spirooxindoles. The aza-Diels-Alder reaction of azoalkenes, which were in situ generated from base dehydrohalogenation of α-halogeno N-acylhydrazones, with 3-methyleneoxindoles afforded functionalized spiro[indoline-3,3′-pyridazin]-2-ones in good yields and with high diastereoselectivity. Under same reaction conditions, the base promoted reaction of α-halogeno N-acylhydrazones and 3-aryliminoindolin-2-ones in DCM at room temperature resulted in functionalized spiro[indoline-3,3'-[1,2,4]triazin]-2-ones in satisfactory yields.