Total synthesis of paniculide A from D-glucose

The chiral total synthesis of paniculide A (1), a highly oxygenated sesquit erpene possessing a bisabolane skeleton, starting from D-glucose is describ ed. The two different approaches, both involved Ferrier's carbocyclization reaction to construct the cyclohexane unit in 1, were explored. The first a pproach, employing the carbocyclization of bicyclic substrate furnished the formal total synthesis. The second approach, designed to suppress the unde sired side reactions observed in the first one, adopted the carbocyclizatio n of a monocyclic substrate, and Claisen rearrangement for the stereoselect ive carbon-carbon bond formation. The successful total synthesis of 1 revea led the effectiveness of the combination of Ferrier's carbocyclization and Claisen rearrangement for the chiral synthesis of highly oxygenated natural products possessing cyclohexane units. (C) 1999 Elsevier Science Ltd. All rights reserved.