Synthetic applications of 2-aryl-4-piperidones. XI a new synthesis of the E-azaeburnamine skeleton

Abstract 17-Azaeburnamine type compound 2 is synthesized by closure of ring E on 1-aminoindolo[2,3- a ]quinolizidine 8 . Compound 8 is obtained by a Neber rearrangement on the corresponding indolo[2,3- a ]quinolizidin-2-one, or by K t BuO cyclisation of 3-amino-2-(2-indoly)piperidin-4-one 16 . In both cases the starting substrate is 4-piperidone 3 . The synthesis of the new [ABED] ring system 6 is also described.