New insights into NIS-promoted aminocyclization. Synthesis of decahydroquinolines from 2-allylcyclohexylamines.

Bishomoallylic secondary amines embodying the 2-allyl-N-benzylcyclohexylamine unit react with NIS to undergo cyclization through 6-endo processes in either the cis or trans series. Nevertheless, when the resulting cis-3-iododecahydroquinolines are treated with Al2O3, the exo derivatives evolve into octahydroindoles and the endo derivatives keep the same backbone, the configuration being retained in the generated alcohols.