The first total synthesis of marine natural product, (−)-majusculoic acid (1) and its seven analogs (9–15), was accomplished in three to ten steps with a yield of 3% to 28%. The strategy featured the application of the conformational controlled establishment of the trans-cyclopropane and stereochemical controlled bromo-olefination or olefination by Horner–Wadsworth–Emmons (HWE) reaction. The potential anti-inflammatory activity of the eight compounds (1 and 9–15) was evaluated by determining the nitric oxide (NO) production in the lipopolysaccharide (LPS)-induced mouse macrophages RAW264.7. (−)-Majusculoic acid (1), methyl majusculoate (9), and (1R,2R)-2-((3E,5Z)-6-bromonona-3,5-dien-1-yl)cyclopropane-1-carboxylic acid (12) showed significant effect with inhibition rates of 33.68%, 35.75%, and 43.01%, respectively. Moreover, they did not show cytotoxicity against RAW264.7 cells, indicating that they might be potential anti-inflammatory agents.
A unique polyketide cladosporactone A along with eight known compounds were isolated from the deep‐sea‐derived Cladosporium cladosporioides. The structure of cladosporactone A was established by spectroscopic analyses, and the absolute configuration was clarified by the theoretical ECD calculation. Cladosporactone A is the first member of polyketide with the 7‐methylisochromen‐3‐one skeleton.
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