Gomerones A-C, halogenated sesquiterpenoids with a novel carbon skeleton from Laurencia majuscula

The structures and relative sterochemistry of three halogenated sesquiterpenoids gomerones A-C, 1-3, isolated from Laurencia majuscula are described. They are representative of a novel carbon skeleton, gomerame, biogenetically derived from cyclization of beta-chamigrene precursor. A biogenetic relationship with related sesquiterpenoids from lower terrestrial plants Hepaticae of genera Bazzania, Mannia, Mylia, and Rebouli as well as higher plants of genera Cupressus and Juniperus has been established. (C) 2008 Elsevier Ltd. All rights reserved.