Communication: Synthesis of 3-O-Benzyl-β-L-Arabinofuranose 1,2,5-Orthopivalate as a Starting Monomer for Ring-Opening Polymerization

We have studied the ring-opening polymerizations of a variety of glucose orthoester derivatives and found that substituents on the monomer play an important role in stereo- and regioregularity of the resulting polymers.^1-3 These substituent effects open the possibility of application to ring-opening polymerizations of other sugar orthoesters to give stereo- and regioregular polysaccharides. Additionally, the ring-opening polymerization of the galactose orthoester derivative⁴ gave stereoregular (1→5)-β-D-galactofuranan.     

Arsenic Compounds in Zoo- and Phyto-plankton of Marine Origin

Major water-soluble arsenic compounds accumulated in some zoo- and phyto-plankton were identified. Zooplankton were collected at sampling stations in the Sea of Japan by a Norpac net towed from 600 m depth to the surface. Phytoplankton were cultivated under axenic conditions. Water-soluble arsenic compounds were extracted repeatedly from plankton tissues by aqueous methanol. The arsenic compounds in the extracts were analyzed by HPLC–ICP/MS. Among zooplankton analyzed in the present study, two carnivorous species, i.e. Amphipoda ( Themisto sp.) and Sagittoidea ( Sagitta sp.), contained arsenobetaine as the dominant arsenic species. Arsenobetaine was the major species in Euphausiacea ( Euphausia sp.), also. The most abundant arsenic compound in the herbivorous Copepoda species ( Calanus sp.), on the other hand, was an arsenic-containing ribofuranoside with a sulfate ester group, and arsenobetaine was only a minor component. Phytoplankton contained arsenic-containing ribofuranosides apparently in a species-speific manner. The arsenic compounds in zooplankton seem to reflect their feeding habit; i.e. carnivorous species eating zooplankton or other small animals accumulate arsenobetaine, while herbivorous ones eating phytoplankton accumulate arsenic-containing ribofuranosides as major arsenic compounds.     

Lithium potassium borate and lithium rubidium borate: new non‐linear optical crystals

The title compounds, LiKB₄O₇ and LiRbB₄O₇, are newly developed non‐linear optical crystals containing two kinds of anionic groups, namely (B₃O₈)^7? and (B₅O₁₀)^5?. The (B₃O₈)^7? groups form infinite spiral chains parallel to the [100] direction, which are interconnected by sharing O atoms with (B₅O₁₀)^5? groups.     

Farnesyl hydroxybenzoic acid derivatives from Ferula kuhistanica.

Four new farnesyl hydroxybenzoic acid derivatives, kuhistanols E-H (1-4), were isolated from the roots of the Uzbekistan medicinal plant Ferula kuhistanica. The structures of the new compounds were elucidated based on spectroscopic and chemical evidence.     

A note on the momentum distribution function for an electron gas

The one-electron momentum distribution function $\text{〈a}{}_{\mathrm{k\sigma }}{}^2\text{a}{}_{\mathrm{k\sigma }}\text{〉}$ for an electron gas is investigated by a diagrammatic analysis of perturbation theory. It is shown that $\text{〈a}{}_{\mathrm{k\sigma }}{}^2\text{a}{}_{\mathrm{k\sigma }}\text{〉}$ has the following exact asymptotic form for large k (k ? p_F; p_F, the Fermi momentum): $\text{〈a}{}_{\mathrm{k\sigma }}{}^2\text{a}{}_{\mathrm{k\sigma }}\text{〉 =}\text{4}\text{9}\text{(}\text{αr}{}_{\mathrm{s}}\text{π}\text{)}{}^2\text{×(}\text{p}{}_{\mathrm{<mtext>F</mtext>}}{}^8\text{k}{}^8\text{) g?(0) + ?}$, where g?(0) is the zero-distance value of the spin-up-spin-down pair correlation function. The physical implications of the above asymptotic form are discussed.     

Synthesis and properties of 1-Benzothiopyrano[2,3-d]-pyrimidine-2,4-(3H)diones (10-thia-5-deazaflavins)

Treatment of 6-arylthiouracils with the Vilsmeier reagent (dimethylformamide-phosphorus oxychloride) gave the corresponding 6-arylthio-5-formyluracils, which could alternatively be prepared by the condensation of 6-chloro-5-formyluracils with thiophenols. Dehydrative cyclization of the above 5-formyluracils with polyphosphoric acid gave 1-benzothiopyrano[2,3-d]pyrimidine-2,4-(3H)diones (10-thia-5-deazaflavins). These 10-thia-5-deazaflavins oxidized alcohols to give the corresponding carbonyl compounds with the aid of strong base, and they were hydrogenated to 1,5-dihydro-10-thia-5-deazaflavins. Treatment of 10-thia-5-deazaflavins with concentrated aqueous potassium hydroxide led to the exclusive formation of 1,5-dihydro-10-thia-5-deazaflavins and 1,5-dihydro-10-thia-5-deazaflavin-5-ones via intermolecular oxidation-reduction (disproportionation) between initially formed 1,5-dihydro-5-hydroxy-10-thia-5-deazaflavins and unchanged 10-thia-5-deazaflavins.