Molecular structures and hypochromism of two purinophanes

The structures of purinophane 1 and its higher homolog 2 were determined by X-ray crystallographic analysis. Hypochroism of 1 and 2 in various media reported.     

New Low‐Molecular‐Mass Gelators Based on L‐Lysine: Amphiphilic Gelators and Water‐Soluble Organogelators

The new L ‐lysine alkali‐metal salts 1 – 5 (M⁺=Na⁺ and K⁺) with different alkyl groups at the N^α‐position were easily synthesized, and their hydro‐ and organogelation properties were investigated. All compounds were H₂O‐soluble, and some salts, especially the potassium salts, functioned as a hydrogenator that could gel water below 2 wt‐%. These salts also had organogelation abilities for many organic solvents.     

Exfoliated nanosheets as a new strong solid acid catalyst

Two-dimensional metal oxide sheets in HTiNbO(5) and HSr(2)Nb(3)O(10), cation-exchangeable layered metal oxides, were examined as solid acid catalysts. Exfoliation of HTiNbO(5) and HSr(2)Nb(3)O(10) in aqueous solutions formed colloidal single-crystal TiNbO(5)(-) and Sr(2)Nb(3)O(10)(-) nanosheets, which precipitated under an acidic condition to form aggregates of HTiNbO(5) nanosheets and HSr(2)Nb(3)O(10) nanosheets. Although esterification of acetic acid, cracking of cumene, and dehydration of 2-propanol were not catalyzed by original HTiNbO(5) because of the narrow interlayer distance, which prevents the insertion of organic molecules, HTiNbO(5) nanosheets functioned as a strong solid acid catalyst for the reactions. Nanosheets of HSr(2)Nb(3)O(10) exhibited no or slight catalytic activity for these reactions. NH(3) temperature-programmed desorption and (1)H magic-angle spinning nuclear magnetic resonance spectroscopy revealed that HTiNbO(5) nanosheets have strong Br?nsted acid sites, whereas HSr(2)Nb(3)O(10) nanosheets do not.     

Cerebroside Langmuir monolayers originated from the echinoderms I. Binary systems of cerebrosides and phospholipids

The surface pressure (pi)-area (A), the surface potential (DeltaV)-A and the dipole moment (mu( perpendicular))-A isotherms were obtained for two-component monolayers of two different cerebrosides (LMC-1 and LMC-2) with phospholipids of dipalmitoylphosphatidylcholine (DPPC) and with dipalmitoylphosphatidylethanolamine (DPPE) on a subphase of 0.5 M sodium chloride solution as a function of phospholipid compositions by employing the Langmuir method, the ionizing electrode method, and the fluorescence microscopy. Surface potentials (DeltaV) of pure components were analyzed using the three-layer model proposed by Demchak and Fort. The contributions of the hydrophilic saccharide group and the head group to the vertical component of the dipole moment (mu( perpendicular)) were estimated. The miscibility of cerebroside and phospholipid in the two-component monolayers was examined by plotting the variation of the molecular area and the surface potential as a function of the phospholipid molar fraction (X(phospholipid)), using the additivity rule. From the A-X(phospholipid) and DeltaV(m)-X(phospholipid) plots, partial molecular surface area (PMA) and apparent partial molecular surface potential (APSP) were determined at the discrete surface pressure. The PMA and APSP with the mole fraction were extensively discussed for the miscible system. Judging from the two-dimensional phase diagrams, these can be classified into two types. The first is a positive azeotropic type; the combinations of cerebrosides with DPPC are miscible with each other. The second is a completely immiscible type: the combination of cerebrosides with DPPE. Furthermore, a regular surface mixture, for which the Joos equation was used for the analysis of the collapse pressure of two-component monolayers, allowed calculation of the interaction parameter (xi) and the interaction energy (-Delta epsilon) between the cerebrosides and DPPC component. The miscibility of cerebroside and phospholipid components in the monolayer state was also supported by fluorescence microscopy.     

Synthesis of deuterium-labeled flavanones

Deuterium incorporation at the C-3 position of flavanones was achieved by treatment of flavanones and 2'-hydroxychalcones with D3PO4 and AcOD. We propose that the deuteration reaction mechanism for 2'-hydroxychalcones substrates is as follows. In the first step, 2'-hydroxychalcones cyclize to the corresponding flavanones by an intramolecular Michael-type reaction. Then deuteriums are incorporated into the flavanones via enolization.     

A novel route to 1-benzyl-1,2,4-triazole derivatives through disproportionation of isothiosemicarbazones

Aromatic isothiosemicarbazones 1–4 underwent disproportionation at elevated temperature in the presence of a thiol or a thiol-releasing substance to give 1-arylmethylene-3-alkylthio-5-aryl-1H-1,2,4-triazole derivatives 6–9 in moderate yields. An isothiosemicarbazone of aliphatic aldehyde with no α-hydrogen did not give rise to the corresponding disproportionation under the similar conditions. Cross reaction occurred between two different isothiosemicarbazones but the cross compound could be isolated only in a poor yield. Any inert solvent markedly inhibited the disproportionation reaction even only with a slight dilution. A tentative reaction mechanism, in which it might involve a potential nitrene-sulfonium ion pair as a key step, is presented.     

Reaction of magnesium cyclopropylidene with N-lithio arylamines: a method for generation of α-amino-substituted cyclopropylmagnesiums and a study for their reactivity with electrophiles

Magnesium cyclopropylidene was generated from 1-chlorocyclopropyl phenyl sulfoxide with i-PrMgCl in THF at −78 °C in high yield by a sulfoxide-magnesium exchange reaction. The generated magnesium cyclopropylidene was found to be reactive with N-lithio arylamines to give α-amino-substituted cyclopropylmagnesiums. The reaction of the α-amino-substituted cyclopropylmagnesiums with several electrophiles was examined and a new method for a synthesis of cyclopropane amino acid derivatives was realized.