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.
Cramer, Nicolai,Laschat, Sabine,Baro, Angelika
p. 2178 - 2181
(2007/10/03)
An Efficient Route to the Tropane Alkaloids
We describe the use of diethylzinc in conjunction with polybromo ketones for the production of oxyallyls, and the interception of these intermediates by furans and methyl pyrrole-N-carboxylate.This methodology allows the production of gramme quantities of tropane alkaloids, and 2-substituted 8-oxabicyclooct-6-en-3-ones that have been either difficult or impossible to prepare.