Synthesis of (−)-δ-N-normethylskytanthine

Abstract (−)-δ-N-normethylskytanthine ( 1 ) has been synthesised from (1R,4R,1′S)-2-(phenylethyl)-2-azabicyclo[2.2.1]hept-5-ene ( 2 ) which undergoes a ketene-amino-Claisen rearrangement by reaction with dichloroketene to generate (1S,6R,1′S)-3-(phenylethyl)-5,5-dichloro-4-keto-3-azabicyclo[4.3.0]non-7-ene ( 3 ), which could be converted to 1 in eleven steps.