Enzymatic Resolution of Tropinone Derivatives

Abstract

The lipase-mediated kinetic resolution of racemic scopoline [(±)-4] and 6-hydroxytropinone [(±)-7] is reported. Whereas (±)-4 is difficult to resolve due to steric hindrance of the hydroxy function, the resolution of (±)-7 with vinyl acetate as acyl donor gave alcohol (+)-7 and the corresponding acetate (-)-9 with high enantiomeric excess. In case of the optimal result of 99% ee for (+)-7 and 80% ee for (-)-9, an E-value of 35 was calculated. The preparative lipase-catalyzed resolution of (±)-7 resulted in almost enantiopure alcohol (+)-7 with >99% ee after one recrystallization.