| The chemistry of cyclic polysulfides from Lissoclinum sp. tunicates, including the total syntheses of the naturally occurring cyclic polysulfide varacin and related compounds are described. The synthesis of varacin provided unambiguous confirmation of the unique dopamine-related benzopentathiepin structure. The synthesis of isolissoclinotoxin A, the regioisomer of the natural product lissoclinotoxin A, is also described and confirms the originally proposed structure for lissoclinotoxin A was incorrect, and in addition, provided experimental data supporting our discovery of the chiral nature of unsymmetrically substituted benzopentathiepins. In addition, the chemical investigation of metabolites from a Didemnum sp. tunicate is presented, including the details of the isolation and characterization of plakinidine D, the first compound belonging to the pyrroloacridine family of metabolites to be isolated from an ascidian. Physical properties and spectroscopic data for the new compound and two derivatives are presented.;In related work on marine microorganisms, the isolation and identification of metabolites from an actinomycete cultured from a shallow water sediment sample is presented. A description of the producing organism is provided along with a detailed account of the isolation and structure elucidation of the metabolites. |
