Calenzanol, the first member of a new class of sesquiterpene with a novel skeleton isolated from the red seaweed Laurencia microcladia from the Bay of Calenzana, Elba Island

The sesquiterpene calenzanol 1, the major metabolite of the red seaweed Lau rencia microcladia Kutzing from the Bay of Calenzana in Elba Island, posses ses a previously unreported ring system, thus establishing a new class of s esquiterpene with a novel skeleton, calenzanane 2. Because of the special a rray of functionalities. I exhibits marked instability, readily rearranging to give the novel indene 3. (C) 2001 Elsevier Science Ltd. All rights rese rved.