Studies directed toward the total synthesis of longifolene

Bukownik, Rudolf Robert (1984) Studies directed toward the total synthesis of longifolene. Masters thesis, Memorial University of Newfoundland.

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Abstract

This thesis describes studies directed toward the total synthesis of longifolene utilizing as a key step an intramolecular Diels-Alder cyclization. Different approaches for the construction of spiro[2.4]hepta-4,6-dienes have been explored and a general route involving the fulvene 63 developed. Nucleophilic addition of methlylithium to this fulvene generates a cyclopentadiene anion in situ, which closes to the requisite cyclopropane system by epoxide ring opening to afford 65. This cyclopentadiene unit will thus serve as the 'left-had portion' for the approach to longifolene which is outlined. Procedures for the preparation and introduction of a suitable 'right-hand portion' have also been examined, these preliminary results have indicated the subtle blend of functionality and reactivity that will be required to generate the dienophilic unit. A suitable triene system 104 was synthesized (unfortunately in low yield) but under the conditions examined the desired Diels-Alder cyclization did not occur.

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