Ring transformation of 6H-cyclopropa[e]pyrazolo[1,5-a]pyrimidine. IV (1). Reduction and reaction of 5a-acetyl-6a-ethoxycarbonyl-5a,6a-dihydro-6H-cyclopropa[e]pyrazolo[1,5-a]pyrimidine-3-carbonitriles with primary amines

The reaction of 5a-acetyl-6-ethoxycarbonyl-5a,6a-dihydro-6H-cyclopropa[e]pyrazolo[1,5-a]pyrimidine-3-carbonitrile ( 1a ) with benzylamine gave ethyl l-benzyl-5-cyano-8a,9-dihydro-2-methyl-1H-pyrrolo[3,4-e]-pyrazolo[1,5-a]pyrimidine-8a-carboxylate ( 2a ), in addition to 5-acetyl-3-benzylamino-1-(4-cyanopyrazol-3-yl)- 2-pyridone ( 3 ). Reaction of 1a with aniline gave ethyl 6-acetyl-8-anilino-3-cyano-7,8-dihydro-4H-pyrazolo-[1,5-a][1,3]diazepine-8-carboxylate ( 4 ), in addition to ethyl 3-cyano-7-methyl-6-pyrazolo[1,5-a]pyrimidine-acrylate ( 5 ). On the other hand, the same reactions of 1b with benzylamine or aniline gave 2b or 8b , respectively. Though catalytic hydrogenation of 1a over 5% palladium-carbon proceeded by ring fission of cyclopropane ring to give 9 , 1a (or 1b ) afforded 4,5-dihydro derivatives ( 13 or 15 ) by catalytic hydrogenation over platinum oxide. The reactivity of 5-methoxy-4,5,5a,6a-tetrahydro-6H-cyclopropa[e]pyrazolo[1,5-a]pyrimidine ( 16 ), which are related analogs of 1a,b , is also described.     

The molecular structure and chemical reactivities of the condensation products of o-substituted benzylidenacetylacetone with hydrazine dihydrochloride

Reaction of o-nitrobenzylideneacetylacetone ( 1a ) with hydrazine dihydrochloride in methanol gave 4-(α-methoxy-o-nitrobenzyl)-3,5-dimethylpyrazole hydrochloride ( 4a ), whose structure was unambigously confirmed by an X-ray crystallographic analysis, via 4-(o-nitrobenzylidene)-3,5-dimethylisopyrazole ( 2a ). Compound 2a was synthesized by condensation of 1a with hydrazine dihydrochloride in acetonitrile. Analogously the corresponding o-chloro derivatives ( 2b, 4b ) were obtained. These were converted to N-methyl ( 6b ) and N-acetyl ( 7a,b ) derivatives and the behaviors on bromination and pyrolysis were investigated.     

A study of the alumina-silica gel adsorbent for the removal of silicic acid from geothermal water: increase in adsorption capacity of the adsorbent due to formation of amorphous aluminosilicate by adsorption of silicic acid

Two kinds of adsorbents (Si adsorbent and Al adsorbent) for the removal of silicic acid from geothermal water to retard the formation of silica scales were prepared using silicic acid contained in geothermal water. The Si adsorbent was prepared by evaporating geothermal water, and the Al adsorbent was prepared by evaporating geothermal water after the addition of aluminum chloride. The specific surface area of the Si adsorbent was small and it's adsorption capacity of silicic acid was low. Although the specific surface area of the Al adsorbent was also small, it was significantly increased by the adsorption of silicic acid and it's adsorption capacity was high. Based on the change in the local structure of aluminum ion by the adsorption of silicic acid, the Al adsorbent was considered to be silica particles covered with crystalline aluminum hydroxide. Moreover, it was concluded that the increase in the specific surface area of the Al adsorbent and the decrease in the zeta potential were due to the formation of an amorphous aluminosilicate with a large surface area and a negative charge (one 4-coordinated Al) by the reaction between aluminum ions and silicic acids.     

Alignment behaviour of the discotic nematic phase of 2,3,6,7,10,11-hexa(4-n-octyloxybenzoyloxy)triphenylene on polyimide and cetyltrimethylammonium bromide coated substrates

The orientational behaviour of the nematic discotic phase of 2,3,6,7,10,11-hexa(4-n-octyloxybenzoyloxy)triphenylene (C8OBT) on substrates coated with a polyimide or cetyltrimethylammonium bromide (CTAB) was investigated by polarizing optical microscopy. The averaged order parameters and directions of the triphenylene core and the carbonyl groups of C8OBT were evaluated by an infrared dichroic method. The discotic nematic (N_D) phase of C8OBT exhibits a homeotropic alignment on a polyimide film, a typical nematic schlieren texture on a glass substrate, and a tilted or planar homogeneous alignment on a CTAB-coated substrate. The order parameter of the triphenylene core is higher on a polyimide film (S = 0.6) than on a CTAB-coated substrate (S = 0.2), whereas that of the carbonyl groups remains roughly constant at 0.2 to 0.3 independent of the substrate for the N_D phase.     

Rational Design and Identification of a Non‐Peptidic Aggregation Inhibitor of Amyloid‐β Based on a Pharmacophore Motif Obtained from cyclo[‐Lys‐Leu‐Val‐Phe‐Phe‐]

Inhibition of pathogenic protein aggregation may be an important and straightforward therapeutic strategy for curing amyloid diseases. Small‐molecule aggregation inhibitors of Alzheimer’s amyloid‐β (Aβ) are extremely scarce, however, and are mainly restricted to dye‐ and polyphenol‐type compounds that lack drug‐likeness. Based on the structure‐activity relationship of cyclic Aβ16–20 (cyclo‐[KLVFF]), we identified unique pharmacophore motifs comprising side‐chains of Leu², Val³, Phe⁴, and Phe⁵ residues without involvement of the backbone amide bonds to inhibit Aβ aggregation. This finding allowed us to design non‐peptidic, small‐molecule aggregation inhibitors that possess potent activity. These molecules are the first successful non‐peptidic, small‐molecule aggregation inhibitors of amyloids based on rational molecular design.     

Glochidionionosides A-D: megastigmane glucosides from leaves of Glochidion zeylanicum (Gaertn.) A. Juss

Five megastigmane glucosides were isolated from the leaves of Glochidion zeylanicum. One of them was a known compound, blumenol C O-beta-D-glucopyranoside (1), and the structures of the four new compounds, glochidionionosides A-D (2-5), were mainly elucidated by spectroscopic methods, including a modified Mosher's method. The absolute configurations of the six-membered ring of glochidionionoside D (5) were deduced by beta-D-glucopyranosylation-induced shift trends in the (13)C-NMR spectra and confirmed by X-ray analysis as its p-bromobenzoate (5b), and the axis chirality of C-7 was determined to be R.     

The effect of UV irradiation on the reduction of Au(III) ions adsorbed on manganese dioxide.

The effect of UV (ultraviolet) irradiation on the adsorption of Au(III) ions on manganese dioxide and their reduction to Au(0) (gold with 0 valence state) was investigated using XPS (X-ray photoelectron spectroscopy) and 197Au M?ssbauer spectroscopy. The UV irradiation accelerated the adsorption and the reduction. From the fact that the proportion of Au(0) estimated from Au 4f XPS spectra for surface analysis was significantly smaller than that from 197Au M?ssbauer spectra for bulk analysis, we deduced that Au(0) was interpenetrated to the inside of manganese dioxide (into deeper places than about 30 A) where XPS is impossible to detect. The content of surface hydroxyl groups on manganese dioxide also increased due to the UV irradiation. The relationship between the charge in the content of hydroxyl groups and the interpenetration of Au(0) is discussed.     

Cobalt oxide supported gold nanoparticles as a stable and readily-prepared precursor for the in situ generation of cobalt carbonyl like species

A treatment of cobalt oxide supported gold nanoparticles (Au/Co₃O₄) under syngas atmosphere effectively generated a cobalt carbonyl-like active species in the reaction vessel. The preparation of Au/Co₃O₄ was quite simple and the in situ generated cobalt species could be used as a stable and easy handling alternative for dicobalt octacarbonyl without bothersome purification prior to use. The reactions, which are sensitive to the purity of the dicobalt octacarbonyl, such as the alkoxycarbonylation of epoxides and the Pauson-Khand reaction, smoothly progressed with Au/Co₃O₄.     

Formation of a silicato complex of zinc in aqueous solution and its accelerating effect on the formation of silica scales in cooling water systems

This study elucidates the effect of zinc (Zn), which is an anticorrosive water additive, on the formation of silica scales from cooling water. In these experiments, the silica scales were analyzed by EPMA, and the results indicate that Zn is sorbed into the silica scales during formation. Measurements of the solubility of Zn(OH)(2) at various concentrations of silicic acid demonstrate that Zn is present as a silicato complex of Zn (SCZ) in cooling water. From adsorption experiments of the SCZ on silica and alumina, which are major components of the silica scales, it can be concluded that the SCZ accelerates the formation of silica scales from cooling water.     

Synthesis of 1,4-dihydro-2-methyl-4-oxo-3-quinolineglyoxylic acid and related compounds

The synthesis of 1,4-dihydro-1-methoxy or ethyl -2-methyl-4-oxo-3-quinolineglyoxylic acid derivatives are described. α-Acetoxy-1,4-dihydro-1-hydroxy-2-methyl-4-oxo-3-quinolineacetic acid esters ( 7a, 7a ), which are key intermediates, were prepared by catalytic hydrogenation of 2-acetoxy-3-acetyl-4-hydroxy-4-(2-nitrophenyl) crotonic acid lactone ( 6 ) in methanol or ethanol.