Diastereoselective Intramolecular Heck Reaction Assisted by an Acetate Group: Synthesis of the Decahydrobenzofluorene Derivative Dasyscyphin E.

The first synthesis of antifungal sesquiterpene quinol dasyscyphin E was achieved starting from trans-communic acid. The process described involves the first diastereoselective synthesis of this type of compound by cyclization of an aryl bicyclosesquiterpene. The acid was efficiently transformed into a sesquiterpene synthon, which was converted into the corresponding bromoaryl sesquiterpene.

First enantiospecific syntheses of marine merosesquiterpenes neopetrosiquinones a and B: evaluation of biological activity.

The first enantiospecific syntheses of neopetrosiquinones A (6) and B (7), two merosesquiterpenes isolated from the deep-water sponge Neopetrosia cf. proxima, from the labdane diterpene trans-communic acid (10) have been achieved. A key step of the synthetic sequence is the simultaneous aromatization of the C ring and the benzylic oxidation on C-7 of an advanced intermediate, mediated by the oxygen-DDQ system.

Synthesis of the putative structure of 15-oxopuupehenoic acid.

Synthesis of the putative structure of the marine natural 15-oxopuupehenoic acid has been achieved starting from commercial (-)-sclareol. Key steps of the synthetic sequence are the Robinson annulation of a β-ketoester and methyl vinyl ketone and an unprecedented cyclization of the resulting α,β-enone, which is mediated by tin(IV) chloride in the presence of N-phenylselenophthalimide. The physical properties of the synthetic compound are somewhat different from those reported for the natural product.

The first synthesis of (-)-isoambreinolide, (+)-vitexifolin D and (+)-vitedoin B.

A very efficient method for synthesizing spirolactones is reported. Treatment of δ,ε-unsaturated carboxylic acids with iodine and triphenylphosphine under mild conditions leads to the corresponding spiro γ-lactones in high yield and with complete stereoselectivity. Utilizing this, the first synthesis of the terpene spirolactones (-)-isoambreinolide, (+)-vitexifolin D and (+)-vitedoin B has been achieved.

First synthesis of antitumoral dasyscyphin B.

The first synthesis of dasyscyphin B, an antitumoral metabolite obtained from the ascomycete Dasyscyphus niveus, has been achieved starting from commercial abietic acid. The key steps of the synthetic sequence are the diastereoselective α-methylation of a ketoaldehyde, followed by an intramolecular aldol condensation and the further Diels-Alder cycloaddition of a dienol ester. The procedure reported will allow the synthesis of related metabolites functionalized in the A ring.