Synthesis of Aryl Amine Derivatives from Benzyl Nitriles via Electrocyclization of in Situ Generated N-SiIyl Ketene Imines

The previously unexplored reactivity of N-silyl ketene imines in organic synthesis is reported. Benzyl nitriles containing an alkenyl or aryl group at the ortho position were smoothly converted into aryl amines in good yields under two sets of mild silylation conditions: (1) nonbasic conditions using TMSNTf2-iPr(2)NEt or (2) basic anionic conditions using lithium diisopropylamide-triisopropylsilyl chloride (LDA-TIPSCl). The reaction probably proceeds via in situ generation of an N-silyl ketene imine followed by 6 pi-electrocyclization and aromatization.