Bengazoles C-G from the sponge Jaspis sp. Synthesis of the side chain and determination of absolute configuration

Five novel antifungal bengazoles from the marine sponge Jaspis sp. are characterized by a derived Mosher ester method and an analysis of exciton coupling in the circular dichroism spectra of the tetra-p-bromobenzoate esters from known bengazole A and synthetic model tetrol. Tetrol is prepared from L-fucose by a seven-step stereoselective process. The fatty acid methyl esters of the bengazoles differ throughout the C12 to C18 chain and are in the series of n, iso or anteiso. Bengazole A has C10 absolute configuration of S and a side chain configuration of 2R,3S,4R,6S.