title: Total synthesis and biological evaluation of the cytotoxic resin glycosides ipomoeassin A-F and analogues.
abstract: A multitasking C-silylation strategy using the readily available compound 26 as a surrogate for cinnamic acid represents the key design element of a total synthesis of all known members of the ipomoeassin family of resin glyosides. This protecting group maneuver allows the unsaturated acids decorating the glucose subunit of the targets to be attached at an early phase of the synthesis, prevents their participation in the ruthenium-catalyzed ring-closing metathesis (RCM) used to form the macrocyclic ring, and protects them against reduction during the hydrogenation of the resulting cycloalkene over Wilkinson's catalyst. As the C-silyl group can be concomitantly removed with the O-TBS substituent using tris(dimethylamino)sulfonium difluorotrimethylsilicate (TASF) in acetonitrile, no separate protecting group manipulations were necessary in the final stages, thus contributing to a favorable overall "economy of steps". In addition to the naturally occurring ipomoeassins, a small set of synthetic analogues has also been prepared by "diverted total synthesis". The cytotoxicity of these compounds was assayed with two different cancer cell lines. The recorded data confirm previous findings that the acylation- and oxygenation pattern of these amphiphilic glycoconjugates is highly correlated with their biological activity profile. Ipomoeassin F turned out to be the most promising member of the series, showing IC(50) values in the low nanomolar range.
authors.affiliation: Max-Planck-Institut für Kohlenforschung, 45470 Mülheim/Ruhr, Germany.
authors.forename: Takashi
authors.initials: T
authors.lastname: Nagano
authors.forename: Jiri
authors.initials: J
authors.lastname: Pospísil
authors.forename: Guillaume
authors.initials: G
authors.lastname: Chollet
authors.forename: Saskia
authors.initials: S
authors.lastname: Schulthoff
authors.forename: Volker
authors.initials: V
authors.lastname: Hickmann
authors.forename: Emilie
authors.initials: E
authors.lastname: Moulin
authors.forename: Jennifer
authors.initials: J
authors.lastname: Herrmann
authors.forename: Rolf
authors.initials: R
authors.lastname: Müller
authors.forename: Alois
authors.initials: A
authors.lastname: Fürstner
mesh_terms: D000970:Antineoplastic Agents / Q000138:chemical synthesis* / Q000737:chemistry / Q000633:toxicity; D002384:Catalysis; D045744:Cell Line, Tumor; D018360:Crystallography, X-Ray; D006001:Glycoconjugates / Q000138:chemical synthesis* / Q000737:chemistry / Q000633:toxicity; D006801:Humans; D008968:Molecular Conformation; D012428:Ruthenium / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D000970:Antineoplastic Agents; D006001:Glycoconjugates; C518346:ipomoeassin B; C518348:ipomoeassin E; C523857:ipomoeassin F; D012428:Ruthenium