Formal total synthesis of 2-pupukeanone via radical mediated cyclisation of an enyne

Diels-Alder reaction of the dienone 12, obtained by C-alkylation of sodium 2,6-dimethylphenoxide, with acrylonitrile and phenyl vinyl sulfones generate the enynes 14 and 17. Tributyltin radical addition to the terminal acetylene in 14 and 17 lead to the vinylstannanes 15 and 18 via 5-exo trig cyclisation of the resulting vinyl radical, which on oxidative cleavage furnishes the isotwistane-diones 16 and 19. Reductive desulfonylation of the diketosulfone 19 furnishes the dione 11, constituting a formal total synthesis of 2-pupukeanone 5 and 2-isocyanopupukeanone 3.

Enantiospecific total synthesis of ent-10, 11-thapsan-10-ol

First enantiospecific total synthesis of optical antipode of the sesquiterpene 10,11-epoxythapsan-10-ol has been described. (R)-Carvone has been employed as the chiral starting material and a combination of intramolecular alkylation and Criegee fragmentation are employed for intramolecular stereospecific transfer of the chirality. An intramolecular diazoketone cyclopropanation and regioselective cyclopropane ring cleavage reactions have been employed for the creation of the three requisite contiguous quaternary carbon atoms.

A method for mapping the distribution and density of rabbits and other vertebrate pests in Australia

The European wild rabbit has been considered Australia’s worst vertebrate pest and yet little effort appears to have gone into producing maps of rabbit distribution and density. Mapping the distribution and density of pests is an important step in effective management. A map is essential for estimating the extent of damage caused and for efficiently planning and monitoring the success of pest control operations. This paper describes the use of soil type and point data to prepare a map showing the distribution and density of rabbits in Australia. The potential for the method to be used for mapping other vertebrate pests is explored. The approach used to prepare the map is based on that used for rabbits in Queensland (Berman et al. 1998). An index of rabbit density was determined using the number of Spanish rabbit fleas released per square kilometre for each Soil Map Unit (Atlas of Australian Soils). Spanish rabbit fleas were released into active rabbit warrens at 1606 sites in the early 1990s as an additional vector for myxoma virus and the locations of the releases were recorded using a Global Positioning System (GPS). Releases were predominantly in arid areas but some fleas were released in south east Queensland and the New England Tablelands of New South Wales. The map produced appears to reflect well the distribution and density of rabbits, at least in the areas where Spanish fleas were released. Rabbit pellet counts conducted in 2007 at 54 sites across an area of south east South Australia, south eastern Queensland, and parts of New South Wales (New England Tablelands and south west) in soil Map Units where Spanish fleas were released, provided a preliminary means to ground truth the map. There was a good relationship between mean pellet count score and the index of abundance for soil Map Units. Rabbit pellet counts may allow extension of the map into other parts of Australia where there were no Spanish rabbit fleas released and where there may be no other consistent information on rabbit location and density. The recent Equine Influenza outbreak provided a further test of the value of this mapping method. The distribution and density of domestic horses were mapped to provide estimates of the number of horses in various regions. These estimates were close to the actual numbers of horses subsequently determined from vaccination records and registrations. The soil Map Units are not simply soil types they contain information on landuse and vegetation and the soil classification is relatively localised. These properties make this mapping method useful, not only for rabbits, but also for other species that are not so dependent on soil type for survival.

Enhancement of Tunneling Density of States at a Junction of Three Luttinger Liquid Wires

We study the tunneling density of states (TDOS) for a junction of three Tomonaga-Luttinger liquid wires. We show that there are fixed points which allow for the enhancement of the TDOS, which is unusual for Luttinger liquids. The distance from the junction over which this enhancement occurs is of the order of x=v/(2 omega), where v is the plasmon velocity and omega is the bias frequency. Beyond this distance, the TDOS crosses over to the standard bulk value independent of the fixed point describing the junction. This finite range of distances opens up the possibility of experimentally probing the enhancement in each wire individually.

Population density of the European provinces of Russia

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Physiological basis of yield variation in response to row spacing and plant density of mungbean grown in subtropical environments

In this study, we investigated the extent and physiological bases of yield variation due to row spacing and plant density configuration in the mungbean Vigna radiata (L.) Wilczek variety “Crystal” grown in different subtropical environments. Field trials were conducted in six production environments; one rain-fed and one irrigated trial each at Biloela and Emerald, and one rain-fed trial each at Hermitage and Kingaroy sites in Queensland, Australia. In each trial, six combinations of spatial arrangement of plants, achieved through two inter-row spacings of 1 m or 0.9 m (wide row), 0.5 m or 0.3 m (narrow row), with three plant densities, 20, 30 and 40 plants/m2, were compared. The narrow row spacing resulted in 22% higher shoot dry matter and 14% more yield compared to the wide rows. The yield advantage of narrow rows ranged from 10% to 36% in the two irrigated and three rain-fed trials. However, yield loss of up to 10% was also recorded from narrow rows at Emerald where the crop suffered severe drought. Neither the effects of plant density, nor the interaction between plant density and row spacing, however, were significant in any trial. The yield advantage of narrow rows was related to 22% more intercepted radiation. In addition, simulations by the Agricultural Production Systems Simulator model, using site-specific agronomy, soil and weather information, suggested that narrow rows had proportionately greater use of soil water through transpiration, compared to evaporation resulting in higher yield per mm of soil water. The long-term simulation of yield probabilities over 123 years for the two row configurations showed that the mungbean crop planted in narrow rows could produce up to 30% higher grain yield compared to wide rows in 95% of the seasons.

Stereoselective Formal Total Synthesis of (-)-Didemniserinolipid B

A formal total synthesis of (-)-didemniserinolipid B from L-(+)-tartaric acid is presented. Key features of the synthesis include construction of the bicyclic acetal core from bisdimethyl amide of tartaric acid and further elaboration by cross metathesis.

Identification and characterization of thionucleosides in the total tRNA of cucumber cotyledons

Total tRNA isolated from cucumber cotyledons grown in the presence of radioactive sulfur was analyzed for the occurrence of thionucleosides. The analysis revealed the presence of at least five thionucleosides which were identified as 5-methylaminomethyl-2-thiouridine (mnm5s2U), 2-methylthio-N6-isopentenyladenosine (ms2i6A), 2-methylthio-N6-hydroxyisopentenyladenosine (ms2io6A), 5-methyl-2-thiouridine (m5s2U) and N-[(9-beta-ribofuranosyl-2- methylthiopurine-2-yl)-carbamoyl]-threonine (ms2t6A). A comparison of relative amounts of these thionucleosides in the total tRNAs of dark-, and light-grown cotyledons shows that the relative amounts of ms2i6A, ms2io6A and ms2t6A remain unchanged whereas mnm5s2U increases with a concomitant decrease in the relative amounts of m5s2U after light treatment of dark-grown cotyledons.

Asymmetric total synthesis of erythromycin. 2. Synthesis of an erythronolide A lactone system

In reporting a total synthesis of erythromycin (la) we described in the preceding paper1 the synthesis of the erythronolide A seco acid derivative 2 in optically active form. In this paper we wish to report a successful transformation of 2 to 12 (synthetically equivalent to erythronolide A) via lactonization and also demonstrate that the proper functionalization of a substrate is critical for the successful lactonization.

Asymmetric total synthesis of erythromycin. 3. Total synthesis of erythromycin

In the preceding paper' we described the preparation of the key lactone intermediate la in optically active form. In this paper we report the synthesis of erythromycin (2) from la. In essence,this transformation involves the glycosidation of a suitable derivative of la with L-cladinose and D-desosamine and the generation of the C-9 ketone functionality.

A stereoselective total synthesis of (−)-seychellene

A stereoselective total synthesis of the tricyclic sesquiterpene (−)-seychellene, starting from (R)-carvone via (R)-3-methylcarvone has been accomplished, employing a combination of intermolecular Michael addition–intramolecular Michael addition sequence, a stereoselective hydrogenation, and an intramolecular alkylation reaction.

An expeditious enantiospecific total synthesis of (+)-7-epi-goniofufurone

Stereoselective synthesis of styryl lactone, (+)-7-epi-goniofufurone was achieved in high yield via simple transformations from tartaric acid. The key step involves the successive stereoselective reduction of ketones with borohydride and selectride.

A total synthesis of the epoxyquinone based antifungal natural product (±)-ambuic acid

A total synthesis of the recently isolated polyketide natural product (+/-)-ambuic acid has been accomplished from the readily available Diels-Alder adduct of cyclopentadiene and 2-allyl-p-benzoquinone through a simple sequence with sound stereocontrol. (c) 2005 Elsevier Ltd. All rights reserved.