Natural and Semisynthetic Immunomodulatory Luakuliide Labdane Diterpenoids.

Spectroscopy-guided isolation of extracts of the Tongan marine sponge cf. (Lamarck, 1814) has resulted in the reisolation of the labdane diterpenoid luakuliide A () and one new congener, luakulialactam A (). In addition to establishing the absolute configuration of , synthetic modifications to the luakuliide framework at key positions has created a set of six derivatives (-) which were used to interrogate a structure-activity relationship relating to the immunomodulatory effects of luakuliide A.

Total Synthesis and Bioactivity Studies of Fungal Metabolite (-)-TAN-2483B.

The first total synthesis of (-)-TAN-2483B, a fungal metabolite possessing a densely functionalized furo[3,4-]pyran-5-one framework, is achieved in 14 steps from d-mannose. Generation of the 2,6-pyran is by cyclopropane ring expansion followed by α-selective alkynylation. Julia-Kocienski olefination introduces the -propenyl side chain.