Tri- and Tetracyclic Azepine Derivatives by Thermally Induced Cyclization of Aminoallenes and Semicyclic 2-Dienamines

Abstract

The 3,3-dimethylindoline-derived allenes 5 are conveniently prepared by organocuprate addition to 2-(phenylethynyl)-3,3-dimethyl-1-methylindolium triflate 4 . Their thermal isomerization affords tetracyclic azepine derivatives 6 . The semicyclic 2-amino 1,3-dienes 11, formed by spontaneous tautomerization of the corresponding aminoallenes, are transformed by thermal reaction into either tricyclic azepine derivatives 13 or benzothiophene-annelated azaheterocycles 14 and 15, depending on the ring size of the enamine moiety and the (hetero)aryl group at C-4 of the 2-dienamine.