title: Transannular cyclization of (4S,5S)-germacrone-4,5-epoxide under basic conditions to yield eudesmane-type sesquiterpenes.
abstract: Transannular cyclizations of germacrone-4,5-epoxide under acidic and thermal conditions have been reported in our previous study. However, this process gave the different and interesting results under basic conditions. (4S,5S)-Germacrone-4,5-epoxide (1) was treated under basic conditions to yield four products (2-5). Compound 2 was an isomer of 1--(4S,5S,9Z)-4,5-epoxygermacra-7(11),9-dien-8-one--and the remaining three compounds (3-5) were eudesmane-type derivatives. Compounds 4 and 5 are new compounds. The structures of the new compounds were determined using high resolution (HR)-MS, one dimensional (1D)-NMR, 2D-NMR and circular dichroism (CD) spectroscopic data. Products 3-5 had the same carbon skeleton as that of eudesmane-type compounds; however, these compounds showed different arrangement of isoprene units to the natural eudesmane-type sesquiterpenes.
authors.affiliation: Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University.
authors.forename: Masanori
authors.initials: M
authors.lastname: Kuroyanagi
authors.forename: Osamu
authors.initials: O
authors.lastname: Shirota
authors.forename: Setsuko
authors.initials: S
authors.lastname: Sekita
mesh_terms: D002942:Circular Dichroism; D003500:Cyclization; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D008968:Molecular Conformation; D045787:Sesquiterpenes, Eudesmane / Q000138:chemical synthesis / Q000737:chemistry*; D045788:Sesquiterpenes, Germacrane / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: C572475:(4S,5S)-germacrone-4,5-epoxide; D045787:Sesquiterpenes, Eudesmane; D045788:Sesquiterpenes, Germacrane