EAST-INDIAN SANDALWOOD OIL .1. STEREOSELECTIVE SYNTHESIS OF (+/-)-BETA-SANTALENE AND (+/-)-BETA-SANTALOL

Sulfuric acid catalyzed rearrangement of γ-lactone 10 provides δ-lactone 11 as the major product. Reduction of 11 to lactols 12 with diisobutylaluminum hydride, followed by a Wittig reaction with isopropyltriphenylphosphorane, gives alcohol 13, which is readily dehydrated to (±)-β-santalene (5). Acid-catalyzed alcoholysis of 11 provides ester 34, whereas ammonolysis of 11 and dehydration of the intermediate hydroxyamide 32 with p-toluenesulfonyl chloride in pyridine provides nitrile 33. Reduction of 33 or 34 with diisobutylaluminum hydride yields aldehyde 31, which has been converted to (±)-β-santalol (2), (±)-trans-β-santalol (7), and dihydro-β-santalol (3). Compounds of the related iso series (38, 43, and 46) have been prepared from γ-lactone 10 using a similar sequence of reactions. © 1979, American Chemical Society. All rights reserved.