Synthesis of cycl[3.2.2]azine and benzo[g]cycl[3.2.2]azine derivatives by use of the [2 + 8] cycloaddition reaction of indolizines and dimethyl acetylenedicarboxylate

The reaction of 1-ethoxycarbonylmethylpyridinium bromides 5a-k with nitro ketene dithioacetal, 1,1-bis-(methylthio)-2-nitroethylene ( 2 ), in the presence of triethylamine in ethanol gave the desired ethyl 2-methyl-thioindolizine-3-carboxylates 3a-k in good yields, along with ethyl 2-methylthio-1-nitroindolizine-3-carboxyl-ates 4a-d . Deesterification of 3 using sodium hydroxide in methanol followed by treatment with polyphosphoric acid gave the corresponding 2-methylthioindolizines 5a-d in good yields. The desulfurization of 5 with Raney-nickel in ethanol occurs smoothly to give the 1,2,3-unsubstituted indolizines 6a-c (a , parent indolizine; b , 8-methylindolzine; c , 6,8-dimethylindolizine). Similarly, pyrrolo[2,1-a]isoquinoline ( 19 ) was also synthesized. These indolizine and pyrrolo[1,2-a]isoquinoline derivatives were allowed to react with dimethyl acetylene to give the corresponding cycl[3.2.2]azine and benzo[g]cycl[3.2.2]azine derivatives in good results.     

Electron beam treatment of lignite-burning flue gas with high concentrations of sulfur dioxide and water

Experiments were carried out to investigate the removals of SO₂ and NO_x from simulated lignite-burning flue gas containing SO₂ (4800 ppm), NO (320 ppm) and H₂O (22%) by electron beam irradiation. Removal efficiencies of SO₂ and NO_x were achieved to reach 97 and 88% at 70°C, and 74 and 85% at 80°C, respectively, with the dose of 10.3 kGy without NH₃ leakage. The higher removal efficiencies of SO₂ and NO_x were observed in simulated lignite-burning flue gas than in coal-fired flue gas containing 800 ppm of SO₂, 225 ppm of NO and 7.5% H₂O at the same treatment condition. The higher removal efficiencies were attributed to the higher concentrations of SO₂, H₂O, and added NH₃. Simulation calculations indicated that the higher concentrations of these components enhance the effective radical reactions to oxidize NO to form NO₂ with HO₂ radical, and to oxidize SO₂ to form SO₃ with OH radical and O₂. The reactions of NO_x with N and NH₂ radicals to produce N₂ and N₂O also promote the NO_x removal. By-product was determined to be the mixture of (NH₄)₂SO₄ and NH₄NO₃ containing a small amount of H₂SO₄.     

Total synthesis of myceliothermophins A-E

Total synthesis of an antitumor compound myceliothermophin A and related compounds based on a convergent synthetic strategy was investigated. A common decalin skeleton of myceliothermophins was stereoselectively constructed by an IMDA reaction. The fully elaborated precursor of myceliothermophins was obtained via aldol reaction of N-protected γ-methoxylactam with decalin aldehyde. By using Teoc group for the protection of nitrogen atom of lactam ring, selective deprotection prior to the hydrolysis of methoxyaminal moiety was successfully achieved to obtain γ-methoxylactams (myceliothermophins C and D). Subsequent hydrolysis of these compounds afforded the corresponding γ-hydroxylactam, and myceliothermophins A and B in high yield. Myceliothermophin E was also synthesized by dehydration of the obtained γ-hydroxylactams. The absolute configurations of myceliothermophins A-E were also successfully determined.     

Iron(III)-catalyzed hydroarylation of propiolic acid with activated arenes

FeCl₃/AgOTf-catalyzed hydroarylation of propiolic acid with electron-rich arenes such as mesitylene, tetramethylbenzene, and pentamethylbenzene in trifluoroacetic acid proceeded to give 3-arylpropenoic acids in moderate to high yields. The same reactions with anisole and 1,4-dimethoxybenzene afforded double hydroarylation products, 3,3-diarylpropionic acids.     

Synthesis of novel fluorescently labeled water-soluble fullerenes and their application to its cellar uptake and distribution properties

Fullerene is a well-known carbon nanomaterial, which can be potentially used for drug manufacture or delivery. Despite several successful examples of utilizing fullerene derivatives as drug candidate materials, their low water solubility under physiological conditions negatively affects the cell penetration efficiency after treatment. In this work, we successfully synthesized two fullerene derivatives with covalently attached fluorescein and boron dipyrromethene (BODIPY) fluorophore moieties, which exhibited cellular uptake and intracellular localization. While both fluorophores decreased their fluorescence intensity in the vicinity of fullerene, the cellar uptake of the fluorescein-modified fullerene was detected via fluorescence microscopy observations. Moreover, decreases in the fluorescence intensities of the intact fluorescein and BODIPY species were observed when both fluorophores and fullerene coexisted in aqueous media.     

Laser deposition of iron on graphite substrates

Pulsed laser deposition of iron atoms on graphite substrates was performed to produce iron carbide films. Mössbauer spectra of the sample revealed that iron carbide was produced on the substrate surface and that an α-Fe layer was produced above the iron carbide layer. When the substrate temperature was maintained at 300 K, the iron carbide layer had a hyperfine magnetic distribution because it contained high density of defects. Laser deposition of Fe at 570 K produced cementite Fe₃C with fewer defects due to enhancement of thermal reactions or annealing of the films. The orientation of hyperfine field of the Fe₃C film was parallel to the substrate surface.     

Nine new secoiridoid glucosides from Jasminum nudiflorum

Phytochemical study of the leaves of Jasminum nudiflorum has led to the isolation of nine new secoiridoid glucosides, jasnudiflosides F-L (1-7), nudifloside D (8) and isooleoacteoside (9). The structures of these compounds were elucidated on the basis of chemical and spectroscopic evidence.     

Fullerene sensors based on calix[5]arene

A new class of fullerene sensors based on calix[5]arenes has produced the highly sensitive detection of C60 and C70.