Asymmetric synthesis of the protoberberine alkaloid (S)-(-)-xylopinine using enantiopure sulfinimines.
A concise enantioselective synthesis of (S)-(-)-xylopinine (1) is described involving the addition of the laterally lithiated derivative of o-tolunitrile of 16 to enantiopure sulfinimine (+)-14. Treatment of the resulting cyano sulfinamide adduct (-)-17b with DIBAL-H accomplishes five operations in a single pot and furnishes the cyclic imine (+)-18 in good yield. Reduction and cyclization affords (S)-(-)-1. Alternatively basic hydrolysis of 17b,c gives isoquinolone 21 that is cyclized and reduced to give (S)-(-)-1.
Davis
Franklin A
FA
Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, USA. fdavis@astro.ocis.temple.edu
Mohanty
Pradyumna K
PK
D001600:Berberine Alkaloids / Q000138:chemical synthesis* / Q000737:chemistry; D002855:Chromatography, Thin Layer; D003500:Cyclization; D007097:Imines / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D017550:Spectroscopy, Fourier Transform Infrared; D013237:Stereoisomerism; D013457:Sulfur Compounds / Q000737:chemistry*
D001600:Berberine Alkaloids; D007097:Imines; D013457:Sulfur Compounds; C453820:xylopinine