Platinum-Catalyzed α,β-Unsaturated Carbene Formation in the Formal Syntheses of Frondosin B and Liphagal

• Published in: Organic letters Vol. 19; no. 1; pp. 294 - 297
• Main Authors: Huynh, Khoi Q, Seizert, Curtis A, Ozumerzifon, Tarik J, Allegretti, Paul A, Ferreira, Eric M
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 06.01.2017; Amer Chemical Soc
• Subjects: Catalysis; Chemistry; Chemistry, Organic; Cycloaddition Reaction; Heterocyclic Compounds, 4 or More Rings - chemical synthesis; Methane - analogs & derivatives; Methane - chemistry; Molecular Structure; Oxidation-Reduction; Phenols - chemistry; Physical Sciences; Platinum - chemistry; Science & Technology; Stereoisomerism; Terpenes - chemical synthesis; ALCOHOLS; SPONGE AKA-CORALLIPHAGA; (+)-LIPHAGAL; POTENT; MECHANISM; FURANS; 4+3 CYCLOADDITION; (+/-)-FRONDOSIN-B; INHIBITOR; ENANTIOSELECTIVE TOTAL-SYNTHESIS
• ISSN: 1523-7060; 1523-7052
• DOI: 10.1021/acs.orglett.6b03682

Formal syntheses of tetracyclic terpenoids frondosin B and liphagal are described. Both synthetic routes rely on the use of platinum-catalyzed α,β-unsaturated carbene formation for the key C–C bond forming transformations. The successful route toward frondosin B utilizes a formal (4 + 3) cycloaddition, while the liphagal synthesis features the vinylogous addition of an enol nucleophile as a key step. Both synthetic routes are discussed, revealing insights into structural requirements in the catalytic α,β-unsaturated carbene reaction manifold.