Spiro epoxide fused cis bicyclo[3.3.0]octanes: enantioselective rearrangement and utilisation of the products in synthetic adventures

The monoketal derived from cis-bicyclo[3.3.0]octane-3,7-dione was converted into the corresponding exo and endo epoxides. The meso exo epoxide was rearranged via enantioselective deprotonation using chiral lithium amide bases to provide a synthetically useful alcohol with up to 80% ee. In contrast it was discovered that, under the same conditions, a related epoxide was less reactive and provided the corresponding alcohol with only 23% ee. The use of these alcohol products in synthesis is also discussed.