TERPENOIDS .12. STEREOCHEMISTRY OF SOME ALCOHOLS DERIVED FROM ENMEIN

The reduction of ketone 9 with LiAl (t-BuO)3H in absolute THF gave alcohols 11 and 13, while the reduction of ketone 9 with NaBH4 in THF-H2O gave an alcohol 10. Alcohol 11 on weak alkaline treatment was epimerized to 10. Similarly, alcohol 13 was epimerized to 15 under similar conditions. Ketolactone ester 20 was reduced with LiAl (t-BuO)3H in anhydrous solvent to give alcohol 24, while it was reduced with NaBH4 in MeOH-H2O to give alcohol 3. Alcohol 24 was epimerized to 3 in weak alkaline conditions. Two other epimeric alcohols 29 and 31 were derived from 3 via a series of reactions. Alcohol 29 was epimerized to 31 by treatment with weak alkali, although the reaction rate was much slower. © 1969.