Enantioselective Synthesis of 3- Azabicyclo[4.3.0]nonane Alkaloids

The stereospecific synthesis of the monoterpene alkaloids (?)-α-skytanthine ((?)- 2 ), (?)-N -demethyle-δ-sky-tanthine((?)- 7 ), and (+)-epidihydrotecomanine (+)- 4 was achieved from a common intermediate 22 , which in turn was obtained from (1R,4S,1′S)-2-(1′-phenylethyl)-2-azabicyclo[2.2.1]hept-5-ene (10) ,via a ketene aza-Claisen rearrangement. The piperidine derivative (+)- 31 , formally the aza-analogue of (+)-isoiridomyrmecin, was also obtained from the same intermediate 22 .