Regioselective and Stereoselective Reductive Aziridinium Ring Cleavage Leading to Azabicyclodecane Architecture: Enantioselective Synthesis of (+)-Subincanadine F

Enantioselective
synthesis of cytotoxic indole alkaloid (+)-subincanadine
F was accomplished starting from the corresponding (S)-acetoxysuccinimide via aziridinium ring formation and its reductive
ring expansion route. Regioselective and stereoselective reductive
aziridinium carbon–nitrogen bond cleavage comprising ring expansions
was a key step. The (S)-OMOM protection of the hydroxyl
moiety adjacent to a benzylic carbon of an in situ formed aziridinium
system was necessary for lithium borohydride-induced reductive ring
expansions, and it also served as a latent source of an essential
ketone carbonyl group for the generation of an α,β-conjugated
system.