Transannular reductive rearrangement of α-amino ketones: construction of aza-tricyclic frameworks of several alkaloids.

Transannular reductive rearrangement of bridged cyclic α-amino ketones led to the aza-tricyclic frameworks azepinoindole, hydrolulolidine, and hydrojulolidine of the typical alkaloids of Stemona, Aspidosperma, and Lycopodium, respectively. This facile approach demonstrates the potential applicability of the Clemmensen-Clemo-Prelog-Leonard reductive rearrangement of tricyclic α-amino ketones for the aza-heterocycle synthesis.