Selectivity of Candida rugosa lipase in simultaneous separation of skeletal isomers, desymmetrization, and kinetic racemate cleavage of 9-oxabicyclononanediols
摘要:
The diols 2 and 3, available in one step from cycloocta-1,5-diene, are selectively acetylated at the (R)-centers using Candida rugosa lipase to give the corresponding enantiopure compounds. In contrast, the (S,S)-enantiomer of 11 is transformed under identical conditions. The stereoselectivity of the lipase has been investigated by modeling of the transition state geometries at the active site of the enzyme. (C) 2003 Published by Elsevier Science Ltd.
O-heterocyclization is applied as a key step in a total synthesis. This highly stereoselective and metal-free transformation introduces four stereocenters in one step. It was chosen to be the pivotal step in the synthesis of Murisolin and 16,19-cis-Murisolin, two annonaceousacetogenins. The efficiency of this synthesis is further illustrated by a stereodivergent late-stage separation of both synthetic routes