The isolation and structures of euphoscopins a and b

Two new toxic substances, euphoscopins A and B, have been isolated from the plant $\text{Euphorbia}$$\text{helioscopia}$ L., and their absolute stereostructures also been elucidated on the basis of their spectral data coupled with an X-ray crystallographic analysis of the $\text{p}$-bromobenzoate readily obtained on treatment of euphoscopin A with $\text{p}$-bromobenzoyl chloride - pyridine. These antitumor substances belong to a group of jatrophone-type diterpenes.     

Synthesis and 13C nmr characterization of some π-excessive heteropolyaromatic compounds

Several π-excessive heteropolyaromatic compounds, which contain furan and thiophen ring and are possible antifungal agents, have been synthesized in good yields according to two general methods. The first method has been used to prepare compounds possessing thiophens linked by their 2- and 5-positions, such as the ter-aryls $\text{2b}$, $\text{2d}$ and $\text{2a}$. Two precursors of these compounds have been obtained either by the Glaser reaction, or using a novel Pd-mediated reaction. The second method,which consists of the Ni-or Pd-catalyzed heteroarylation of heteroarene halides via cross-coupling with heteroaryl Grignard reagents or zinc halides,has been used to prepare the bi-aryls $\text{1a-e}$, which contain two heteroaromatic units, and the ter-aryl $\text{2c}$. Compound $\text{1e}$ has been also prepared starting from 2-(2-thienyl) furan ($\text{1c}$) by selective lithiation, followed by bromination.The ¹³C NMR signals of $\text{1a-e}$ and $\text{2a-d}$ have been assigned on the basis of the literature data and by relaxation measurements. Relaxation data have been also used to obtain qualitative informations on the conformational equilibria of the bi-aryls $\text{1a}$, $\text{1c}$ and the ter-aryls $\text{2a-d}$.     

Isolation and stereostructures of citreoviral,citreodiol, and epicitreodiol

Three new metabolites (citreoviral, citreodiol, and epicitreodiol) have been isolated from the mycelium of $\text{Penicillium}$$\text{citreo-viride}$ B.(IFO 6050) and their stereostructures have been elucidated on the basis of their spectral data coupled with some chemical evidence. Furthermore, the absolute configurations of citreodiol and epicitreodiol have been determined by syntheses of the corresponding antipodes starting from L-rhamnose.     

Total synthesis and the absolute configuration of citreoviral and citreoviridin

Both citreoviral and citreoviridin, metabolites of $\text{Penicillium citreo-viride}$ B., have been synthesized starting from D-glucose, in connection with which their absolute configuration has also been established.     

The conversion of methylenomycin A to natural botryodiplodin and their absolute configurations

Natural (?)-botryodiplodin($\text{1}$) has been synthesized from an antibiotic methylenomycin A ($\text{2}$). The absolute configurations of (?)-botryodiplodin($\text{1}$ and methylenomycin A ($\text{2}$) have also been established as shown in $\text{1}$ and $\text{2}$ respectively.     

Fomajorin S and D from fomes annosus (FR) cooke

Fomajorin S and D, two new isocoumarins have been isolated from the sporophores and ageing cultures of Fomes annosus, and have been assigned structures $\text{2}$ and $\text{:3}$ respectively on the basis of spectroscopic evidence of the natural products and their derivatives.     

3,4-Epoxyprecocenes: thermal and acid promoted dimerisation

Thermal dimerisation of 3,4-epoxyprecocene II ($\text{2b}$) in absence of solvents afforded high yields (65%) of tetrahydrofuran dimer $\text{4}$ and minor amounts of benzopyran-3-one $\text{3}$. On the other hand, two new dimers, γ-hydroxyketone $\text{5}$ and dioxane $\text{7a}$ have also been isolated from treatment of $\text{2b}$ with different acids. Structural elucidations for all these dimers have been carried out by spectroscopic and analytical methods, combined with the use of selected deuteriated precursors in the corresponding dimerisation procedures.     

Labdane diterpene glycosides with 6-deoxy-L-idose from Aster spathulifolius Maxim.

Three labdane type diterpene glycosides ($\text{1}$, $\text{2}$ and $\text{3}$) with 6-deoxy-L-idose have been isolated from Aster spathulifolius Maxim. and their structures have been determined on the basis of chemical and spectral data.     

Structures of kokzeylanol and kokzeylanonol two new natural tri- and tetra- oxygenated D:A-friedo-oleananes

Kokzeylanol and kokzeylanonol obtained from $\text{Kokoona}$$\text{zeylanica}$ have been shown to be 6β,27-dihydroxy-D:A-friedo-olean-3-one ($\text{1}$) and 6β,27-dihydroxy-D:A-friedo-oleana-3,21-dione ($\text{2}$), respectively by the deoxygenatlon of their 27-acetoxy derivatives using Lithium-ethylene diamine reduction coupled with spectroscopic and irradiation methods. Kokzeylanonol represents the first tetraoxygenated D:A-friedo-oleanane isolated from a natural source.     

18-oxygenated polyfunctional steroids from the gorgonian isishippuris

Two new 18-oxygenated, polyfunctional steroids ($\text{2}$, $\text{3}$) related to hippurin-1 have been isolated from the gorgonian $\text{Isis}$$\text{hippuris}$ collected off Okinawa and their structures were determined.     

Ichthyotoxic sesterterpenoids from the neo guinean sponge carteriospongia foliascens

Six 20,24-dimethylscalarane derivatives ($\text{5}$, $\text{12}$, $\text{15}$, $\text{17}$, $\text{19}$, and $\text{21}$) have been isolated from the Neo Guinean sponge Carteriospongia foliascens. Compound $\text{12}$ is identical with a C₂₇ tetracyclic terpene previously isolated from an Australian specimen of the same sponge. The five other derivatives are new and their structures have been established on the basis of their spectral data. The structure of $\text{5}$ was confirmed by single-crystal X-ray diffraction and that of $\text{15}$ by chemical correlation with $\text{12}$. The configuration at C-4 for all these compounds has been determined through ¹³C NMR data. Evidence leading to reverse the configuration at this centre in previously reported C₂₇ tetracyclic terpenes is discussed. An ecological function is suggested for these molecules.     

New polyoxygenated steroidal glucosides from chrysolina hyperici (coleoptera : chrysomelidae)

Two new polyoxygenated steroidal glucosides ($\text{1}$ and $\text{2}$) have been isolated from the defensive secretion of C. hyperici and their structures have been determined by spectroscopic and chemical methods.     

Structural and conformational studies on citreoviridinol and isocitreoviridinol: syntheses of some 2,6-dioxabicyclo[3.2.1]octanes

Isocitreoviridinol has been newly isolated from the mycelium of $\text{Penicillium citreo-viride}$ B. (IFO 6050) together with citreoviridinol, and their stereostructures have also been elucidated by means of chemical method: the 2,6-dioxabicyclo[3.2.1]octanes have been made, one of which is regarded as a promising synthetic intermediate of citreoviridinol. In addition, isocitreoviridinol diacetate has been derived from citreoviridin in 3 steps.     

Enzymic control of stereochemistry among the Thalictrum bisbenzylisoquinoline alkaloids

The new bisbenzylisoquinolines (+)-tha1igrisine $\text{1}$ and (+)-tha1iphylline ($\text{6}$) have been isolated from $\text{Thalictrum minus}$ var. $\text{microphyllum}$. Four rules are described which correlate the structures of Thalictrum bisbenzylisoquinolines with their stereochemistry at C-1 and C-1'. As a result, (+)-tha1rugosamine is shown to be identical with (+)-homoaromo1ine ($\text{14}$). (+)-Thalisamine and (+)-N'-norhernandezine are also identical and are represented by expression $\text{18}$. The sole exception to the rules is (-)-isothalidezine ($\text{15}$).     

Isolation and stereostructures of neocitreoviridinol and epineocitreoviridinol

Both neocitreoviridinol and epineocitreoviridinol with a 2,5-dioxabicyclo[2.2.1]-heptane ring have been isolated as new metabolises of $\text{Penicillium citreo-viride}$ B., and their stereostructures have also been elucidated on the basis of their spectral data coupled with molecular mechanics calculations. In addition, a promising synthetic intermediate for neocitreoviridinol has been made.     

Three fungitoxic cyclopentanoid sesquiterpenes from stromata of epichloetyphina

New fungitoxic sesquiterpenes, chokol A (1), B (2), and C (3), have been isolated from stromata of $\text{Epichloe}$$\text{typhina}$. Their structures and the relative configuration of 3 have been also elucidated from spectral data.     

The synthesis of the potent anti-herpes virus agent, E-5(2-bromovinyl)-2′-deoxyuridine and related compounds

The synthesis of $\text{E}$-5(2-bromovinyl)-2′-deoxyuridine in good yield from deoxyuridine $\text{via}$ an intermediate organopalladium derivative is described. The corresponding chloro and iodo compounds have also been made as have the corresponding bromo and iodo 2′-deoxycytidines.     

Synthesis of erythro- and threo-α-bromo-α′-fluorosuccinic acids

$\text{erythro}$- and $\text{threo}$-α-Bromo-α′-fluorosuccinic acids have been prepared from their corresponding dimethyl esters. Because of the extreme readiness of elimination of hydrogen fluoride in basic medium, a special method of acid hydrolysis had to be applied. Hydrogen and fluorine NMR spectra are reported.     

New masked building block for isoprenoid polyene chain synthesis

The new building blocks $\text{2}$, $\text{3}$, and $\text{4}$ have been effecively synthesized starting from 2-hydroxymethyl-4-phenylthio-1-butene ($\text{1a}$). A convenient synthesis of retinoic acid methyl ester ($\text{9}$) using $\text{2}$ is also described.     

Bioactive marine metabolites IX. Mycalisines A and B,novel nucleosides which inhibit cell division of fertilized starfish eggs,from the marine sponge mycale sp.

Two novel nucleosides, mycalisines A and B, have been isolated from a marine sponge and their structures elucidated as 4-amino-5-cyano-7-(3-$\text{O}$-methyl-5-deoxy-β-D-$\text{erythro}$-pent-4-enofuranosyl)-pyrrolo[2,3-$\text{d}$]pyrimidine and 5-cyano-7-(3-$\text{O}$-methyl-5-deoxy-β-D-$\text{erythro}$-pent-4-enofuranosyl)-pyrrolo[2,3-$\text{d}$]pyrimidine-4-one, respectively. Both compounds inhibit cell division of fertilized starfish eggs.