PhICl₂-Mediated Conversion Of Enamines To α,N-Dichloroimines And Their Reverse Conversion Mediated By Zn

N-Chloroimine derivatives are a class of rare building blocks in organic synthesis.They can be used for important transformations in organic synthesis. For example,they have found applications in the synthesis of sulfonium salts via reactions withsulfides. Furthermore, N-chloroimine could be converted to the corresponding amidederivatives through Beckmann rearrangement. The currently existing methods for theformation of N-chloroimine can be summarized as three general approaches, namely,the dichlorination of amines with the subsequent base-mediated elimination, the directoxidation of imine compounds by reacting with NaOCl, or with NCS.A novel method about PhICl2-mediated conversion of enamines to α,N-dichloroimines has been established, with a class of enamines being used as thestarting material, and the reacton being carried out in DMF at rt. The method exhibitsan excellent functional group tolerance such as the combination of twoelectron-withdrawing groups or replacing one of the electron-withdrawing groupswith an electron-donating group. Under the optimal conditions, a series of α,N-dichloroimines were synthesized in satisfactory yields. A possible mechanism forthe PhICl2-mediated oxidative chlorination reaction has been studied and the structureof the intermediate has been confirmed. The structure of the product were confirmedby1H NMR,13C NMR, HRMS, IR and X-ray.At the beginning, we envisaged that the treatment of α, N-dichloroimine with Zndust in an appropriate solvent might give2H-azirine compound. However, in theprocess we found a new method for reductive dehalogenation of α, N-dichloroiminecompounds. The reaction of α, N-dichloroimine compound with Zn in MeOHunderwent a reversion reaction to give the starting enamine.