Resolution of 7,7-dimethylbicyclo[3.2.0]hept-2-en-6-one using Mortierella ramanniana and 3α,20β-hydroxy-steroid dehydrogenase, photochemistry of 3-hydroxy-7,7-dimethylbicyclo[3.2.0]heptan-6-ones, and the synthesis of (+)-eldanolide
The fungus Mortierella ramanniana reduced 7,7-dimethylbicyclo[3.2.0]hept-2-en-6-one (1) to give the (6S)-endo-alcohol (9) and the (6S)-exo-alcohol (10). In contrast the enzyme 3α,20β-hydroxy-steroid dehydrogenase was found to give the (6S)-endo-alcohol (9) and recovered optically active ketone. Both processes produced the alcohol (9) in high optical purity. The (6S)-endo-alcohol (9) was converted into the lactone (+)-(4) a late stage synthon for the pheromone eldanolide (+)-(11).