Total Synthesis of Tamariscene

Abstract

Sesquiterpene hydrocarbons of the pacifigorgiane and of the novel tamariscane skeleton were detected by GC-MS in the essential oils of Aristolochia baetica collected at the Algarve. The same compounds were isolated from Frullania fragilifolia, Frullania tamarisci and Valeriana officinalis respectively, and submitted to NMR investigation. By NMR investigation only relative configurations can be determined, the absolute stereochemistry has to be identified by chemical correlation: closely related structures are transformed into the desired structure or, if these structures are unknown, total synthesis is needed. In the case of tamariscene, the first compound isolated with the tamariscane skeleton, total synthesis had to be undertaken to corroborate its postulated structure and to reveal its absolute configuration.