Hetero‐ Cope ‐Umlagerungen. 4. Mitteilung . Regiokontrollierte Indolsynthesen

Hetero‐ Cope ‐Rearrangements, Regio‐Controlled Synthesis of Indoles The reaction of O ‐deprotonated N ‐phenylhydroxylamines 1 with various electron‐deficient allenes 2 , 14 , 16 gives, via Michael addition and Cope ‐rearrangement, substituted anilines 5 , which are easily convertible into indoles 6 . In this manner, sulfoxides 17 , serve as equivalents of 2‐vinylindoles. Diels ‐ Alder reaction with this 2‐vinylindole equivalent followed by indolisation affords isoquinuclidine derivative 21 which may be a useful precursor for the preparation of Iboga alkaloids.