Three new sesquiterpenes from the black heartwood of Cryptomeria japonica

Three new sesquiterpenes, (4S)-2,6,10-bisaboratrien-4-ol-1-one (1), 1,8-epoxy-1(6),2,4,7,10-bisaborapenta-en-4-ol (2), and 1-methoxy-4-cadinene (3) have been isolated from the black heartwood of Cryptomeria japonica. Compounds 1 and 2 were designated sugikurojinols A and B, respectively, and the structures of compounds 1-3 were established by extensive NMR experiments. Compounds 1 and 2 were also examined for antibacterial activity against Staphylococcus aureus and Escherichia coli, and for termiticidal activity against Coptotermes formosanus SHIRAKI.     

The doublet instabilities of the Hartree-Fock solutions for the cation and anion radicals of fulvalene systems

The doublet instabilities of the restricted Hartree-Fock (RHF) solutions for the ion radicals of fulvalene systems, some of which have been known to show the lattice instabilities, are examined in the framework of the semiempirical SCF MO approximation. The RHF solutions for the anion radical of heptafulvalene and the cation radical of pentafulvalene are found to be doublet unstable at the conventional D_2h nuclear arrangement. We calculate the broken-symmetry charge-density-wave (CDW) solutions lower in energy than the usual symmetry-adapted RHF solutions and examine their properties. It is shown that the energy lowerings due to the CDW solutions are very small in both the ion radicals, but their density matrix elements are remarkably different from those for the symmetry-adapted RHF solutions. It is also shown that the proton hyperfine splittings for the anion radical of heptafulvalene calculated assuming the CDW solution are in good agreement with the experimental values. Finally, we refer to the relationship between the doublet instability of the RHF solution and the lattice instability.     

Occurrence of polygodial and 1-(2,4,6-trimethoxyphenyl)-but-2-en-1-one from some ferns and liverworts: role of pungent components in bryophytes and pteridophytes evolution

The New Zealand fern Blechnum fluviatile and liverwort, Hymenophyton flabellatum produce the characteristic pungent compounds, (-)-polygodial, a sesquiterpene dialdehyde, and 1-(2,4,6-trimethoxyphenyl)-but-2-en-1-one, respectively. The former compound has been isolated from the Japanese liverwort, Porella vernicosa complex and the latter one from the Japanese fern, Arachinoides standishii. The occurrence of both compounds in both pteridophytes and bryophytes provides another important link between bryophytes and ferns.     

Solvent free amination reactions of aryl bromides at room temperature catalyzed by a (pi-allyl)palladium complex bearing a diphosphinidenecyclobutene ligand

An air- and moisture-stable (pi-allyl)palladium complex bearing a unique diphosphinidenecyclobutene ligand effectively catalyzes amination reactions of aryl bromides with amines, where the reactions proceed under mild conditions without solvent, with 2 mol % of catalyst and 1 equiv of t-BuOK at room temperature. Under these conditions the amination products were obtained in good to excellent isolated yields.     

Preparation of sterically protected 3,4-bis[(2,4,6-tri-tert-butylphenyl)phosphinidene]cyclobutene derivatives having ring-fused structures

[reaction: see text] Sterically protected 3,4-diphosphinidenecyclobutenes, having ring-fused structures, were prepared. Structures of 8,9-bis[(2,4,6-tri-tert-butylphenyl)phosphinidene]bicyclo[5.2.0]non-1(7)-ene and its dichloropalladium(II) complex were analyzed by X-ray crystallography. A geometrical change induced by the complex formation was exhibited by X-ray crystallographic analysis. The geometrical change in solution was also suggested by (1)H NMR spectroscopy in CDCl(3).     

A major urinary protein of the domestic cat regulates the production of felinine, a putative pheromone precursor

Domestic cats spray urine with species-specific odor for territorial marking. Felinine (2-amino-7-hydroxy-5,5-dimethyl-4-thiaheptanoic acid), a putative pheromone precursor, is excreted in cat urine. Here, we report that cauxin, a carboxylesterase excreted as a major urinary component, regulates felinine production. In vitro enzyme assays indicated that cauxin hydrolyzed the felinine precursor 3-methylbutanol-cysteinylglycine to felinine and glycine. Cauxin and felinine were excreted age dependently after 3 months of age. The age-dependent increases in cauxin and felinine excretion were significantly correlated. In mature cats, cauxin and felinine levels were sex-dependently correlated and were higher in males than in females. In headspace gas of cat urine, 3-mercapto-3-methyl-1-butanol, 3-mercapto-3-methylbutyl formate, 3-methyl-3-methylthio-1-butanol, and 3-methyl-3-(2-methyldisulfanyl)-1-butanol were identified as candidates for felinine derivatives. These findings demonstrate that cauxin-dependent felinine production is a cat-specific metabolic pathway, and they provide information for the biosynthetic mechanisms of species-specific molecules in mammals.     

Synthesis of heterocyclic compounds via nucleophilic aroylation catalyzed by imidazolidenyl carbene

Xanthones and acridones were synthesized from 3,4-difluoronitrobenzene and 2-fluorobenzaldehydes in two or three steps. The key step was nucleophilic aroylation catalyzed by imidazolidenyl carbene. The nucleophilic aroylation of 3,4-difluoronitrobenzene afforded 2,2'-difluoro-4-nitrobenzophenones. The cyclization of the difluorobenzophenones with O-nucleophile and N-nucleophile yielded 3-nitroxanthones and 3-nitroacridones, respectively. Indazole, quinolino[2,3-b]quinoxaline, and thianaphtho[2,3-b]quinoxaline derivatives were also synthesized via nucleophilic aroylation of 2,3-dichloroquinoxaline followed by cyclization with nucleophiles.