Approach to Spirocyclohexadienimines and Corresponding Dienones through Radical ipso Cyclization onto aromatic azides.

Cyclization of aryl radicals at the ipso-position of p-azido-substituted benzamides or 2-(phenyl)acetamides results in effective production of spirocyclohexadieniminyl radicals through prompt elimination of molecular nitrogen by transient azidocyclohexadienyl radicals. The outcoming iminyl radicals can be exploited in a new protocol for the synthesis of oxindoles or quinolones bearing spiro-cyclohexadienimine/-cyclohexadienone rings which are pivotal intermediates in the preparation of various biologically active indole compounds.