was developed to prepare the tricycle diterpene intermediates 1–3 starting from commercially available (−)-sclareol. This improved approach involving four-step reactions provides large-scale (30–40 g) methyl ent-isocopalate in 61% overall yield, which could supply sufficient material for the synthesis of marine natural products containing tricyclic diterpenes.
A series of polycyclic sulfides (C15, C20, C25, C30) deriving from regular isoprenoids has been characterized in sediments by mass spectrometry, synthesis of C20 members, and NMR structural elucidation of two C30 isomers isolated from a geological sample.