| Investigation of the absolute configuration and biological activity of three nakafuran derivatives isolated from the marine sponge Dysidea etheria resulted in the determination of the absolute configuration of the secondary alcohol 5-hydroxynakafuran-8, 40, by means of a modified Horeau's method. This modification was the substitution of 2-phenylbutanoyl chloride for 2-phenylbutanoic anhydride. The stereochemistry of the other two nakafurans, 5-acetoxy-nakafuran-8, 41, and 5-ketonakafuran-8, 42, was assigned by chemical degradation of transformation to the lead compound 40. All three nakafurans were evaluated for their phytotoxicity, cytotoxicity, insecticidal and antimicrobial activity.;Investigation of the cytotoxic organic extract of the marine green alga Neomeris annulata resulted in the isolation of three novel metabolites, 2-bromo-5-hydroxy-cis-selin-6-ene, 114, 1;The breadth of application of the modified Horeau's method was evaluated with nine secondary alcohols of varying steric hindrance. These alcohols were esterified with both the anhydride and acid halide. The results demonstrated that sterically hindered secondary alcohols gave higher optical yields when resolved with the acid halide and less hindered secondary alcohols gave better optical yields with the anhydride. |
