A Synthetic Route to 3,3-Diphenyl-2-indolinone Derivatives

N-Aryl-α-chloro-α,α-diphenylacetimidoyl chlorides were prepared from Schiff bases and dichlorocarbene generated by use of the phase transfer catalyst. Treatment in sulfuric acid gave 3,3-diphenyl-2-indolinone derivatives. The synthetic route to 2-indolinone was found to give a higher overall yield than that by other methods. 2,2-Dichloro-1,3-diphenylaziridine gives α-chloro, α-acetoxy or α-hydroxy-α,α-diphenylacetanilide on treatment with sulfuric acid. Comparison of 2,2-dichloro-1,3-diphenylaziridine, 2,2-dichloro-1,3,3-triphenylaziridine and N-aryl-α-chloro-α,α-diphenylacetimidoyl chloride in their reactivities with sulfuric acid shows that the pathway of the reaction is governed by the character and number of substituents at the reaction center where carbonium ions are developed.