Microbiological transformation of an ent-pimaradiene hydrocarbon by Gibberella fujikuroi

The hydrocarbon 9,13-epi-ent-pimara-7,15-diene has been obtained from its 18-hydroxy derivative by treatment with Ph₃/CCl₄ and subsequent reduction with tri-n-butyltin hydride. The incubation of this diterpene with the fungus Gibberella fujikuroi afforded 1α,9α-dihydroxy-7α,8α-epoxy-13-epi-ent-pimara-15-ene. The main difference between the biotransformation of the hydrocarbon and that of the corresponding 18-alcohol is that in the former, the rearrangement of the epoxy group to give 7-oxo-derivatives was not observed. However, the sequence of reactions 7α,8α-epoxidation, hydroxylation at C-9α and subsequent C-1α hydroxylation occurred in both biotransformations.     

Avian diversity and behavior in an Eocene coastal plain,Svalbard: the ichnological evidence

Abstract

This study presents an ichnotaxonomical assessment of bird footprints from a coastal plain setting in the Eocene lower to middle Aspelintoppen Formation in Brongniartfjellet and Storvola, Svalbard. These footprints are unique evidence for Paleogene birds from Svalbard and the second evidence of Paleogene avifauna of the Arctic (along with scarce fossil remains from Ellesmere Island). The analyzed footprints are assigned to six ichnotaxa belonging to three ichnofamilies: Aquatilavipes isp., avian footprint morphotype A and B (ichnofamily Avipedidae); Gruipeda cf. G. abeli, Gruipeda cf. G. dominguensis (ichnofamily Gruipedidae); and Gyeongsangornipes isp. (ichnofamily unknown). Associated invertebrate ichnofossils include Helminthoidichnites tenuis, Cochlichnus anguineus, and Helminthopsis isp. The avian footprints reflect small, medium-sized and rare large birds that can be morphologically compared to those of modern relatives including crane, heron, plover, moorhen, gallinule, oystercatcher and curlew. It is also proposed that in situ sets of shorebird footprints showing a preferred orientation, not composing trackways and showing overprinting, can be used as an indicator of the position and orientation of the shoreline.     

13C NMR spectra of olean-18-ene derivatives

The ¹³C NMR signals of sixteen derivatives of olean-18-ene-triterpenes have been assigned.     

New diterpenes from Sideritis candicans

The three new diterpenes candol-A (ent-16-kauren-7α-ol, I), candol-B (ent-16-kauren-18-ol, III) and epicandicandiol 7β-monoacetate (ent-7α-acetoxy-16-kauren-18-ol, V) as well as epicandicandiol (VII) have been isolated from Sideritis candicans.     

Linkiol,a new sesquiterpene from Ferula linkii

A new sesquiterpene ester, linkiol with a daucane skeleton was isolated from Ferula linkii.     

Comparative phytochemistry of the genus Sideritis from the Canary Islands

Nine species, drawn from two sections of the genus Sideritis (Labiatae) from the Canary Islands were examined. Terpenoids, sterols, flavonoids, coumarins and lignans were isolated. From the chemosystematic point of view the Sideritis species were divided into three groups. The first was formed by S. argosphacelus and S. macrostachya, the second by S. bolleana, S. canariensis, S. candicans, S. candicans var. TFC 3890, S. dasygnaphala and S. dendrochahorra, while the third contained S. gomerae and S. cabrerae.     

The 13C NMR spectra of some ent-18-hydroxykaur-16-enes

The ¹³C NMR spectra are reported for thirteen ent-18-hydroxykaur-16-enes and their value for determining the C-4 stereochemistry is discussed.     

Geometry of Multi-Tube Carbon Clusters and Electronic Transmission in Nanotube Contacts

Molecular Engineering -