Halichonines A, B, and C, novel sesquiterpene alkaloids from the marine sponge Halichondria okadai Kadota

Novel sesquiterpene alkaloids, halichonines A (1), B (2), and C (3), were identified from the marine sponge Halichondria okadai Kadota. By spectroscopic analyses and synthesis, their structures were revealed to include a 6,6-bicyclic ring system and two prenylated amine moieties. In addition, 2 induced apoptosis in HL60 human leukemia cells.     

New method for comprehensive detection of chemical warfare agents using an electron-cyclotron-resonance ion-source mass spectrometer

We developed a detection technology for vapor forms of chemical warfare agents (CWAs) with an element analysis system using an electron cyclotron resonance ion source. After the vapor sample was introduced directly into the ion source, the molecular material was decomposed into elements using electron cyclotron resonance plasma and ionized. The following CWAs and stimulants were examined: diisopropyl fluorophosphonate (DFP), 2-chloroethylethylsulfide (2CEES), cyanogen chloride (CNCl), and hydrogen cyanide (HCN). The type of chemical warfare agents, specifically, whether it was a nerve agent, blister agent, blood agent, or choking agent, could be determined by measuring the quantities of the monatomic ions or CN(+) using mass spectrometry. It was possible to detect gaseous CWAs that could not be detected by a conventional mass spectrometer. The distribution of electron temperature in the plasma could be closely controlled by adjusting the input power of the microwaves used to generate the electron cyclotron resonance plasma, and the target compounds could be detected as molecular ions or fragment ions, enabling identification of the target agents.     

Elongation of carbonyl compounds by utilizing electroreduction as a key step

The transformation of aldehydes, ketones and esters to the next higher homologous aldehydes was accomplished by utilizing electroreductive 1,2-elimination as a key step.     

Synthesis of labda-8(17),13(14)-diene-15,16-olide and 15,16-epoxy-labda-8(17),13(16)-14-triene and their rearrangement to clerodane derivatives

The title compounds 1b and 1c were synthesized from manool. On treatment with either trifluoroacetic acid or formic acid 1b provided in nearly 100% yield 4a with a rearranged labdane skeleton. With sulfuric acid, however, 1b gave solely Δ^8,9-isomer 5. Reduction of 4a with lithium diisobutylaluminum hydride afforded 4b. On treatment with sulfuric acid 4a reverted to 5. Rearrangement of the epoxide 6 with boron trifluoride- etherate led to a complex product mixture from which no pure substance was obtained.     

Efficient asymmetric synthesis of α-amino acids through hydrogenation of α,β-dehydroamino acid residue in cyclic dipeptides

A series of cyclo (Δaminoacyl-L-Ala) ($\text{4}$) (Δ=α,β-dehydro) were prepared from cyclo(Gly-L-Ala) and corresponding aldehyde, and hydrogenated with Pd black in MeOH. Chiral inductions producing cyclo (L-aminoacyl-L-Ala) ($\text{5}$) from $\text{4}$ were 96–99% in the case of L-Aba (2-aminobutanoic acid), L-Val, L-Leu, and L-App (2-amino-5-phenylpentanoic acid) as an L-aminoacyl moiety in $\text{5}$. Pure L-Leu, L-Aba, and L-App were synthesized in preparative scale from corresponding $\text{4}$ through asymmetric hydrogenation and acid-hydrolysis.     

Vapor—liquid equilibria for the ternary Ethanol—2-butanone—benzene system at 298.15 K

Vapor—liquid equilibrium data for the ternary ethanol—2-butanone—benzene system and its constituent binary systems at 298.15 K are presented. The results are correlated with the Wilson, original and modified UNIQUAC equations and the UNIFAC group contribution method.     

Chiral Carboxylic Acid Enabled Achiral Rhodium(III)‐Catalyzed Enantioselective C−H Functionalization

Reported is an achiral Cp^xRh^III/chiral carboxylic acid catalyzed asymmetric C?H alkylation of diarylmethanamines with a diazomalonate, followed by cyclization and decarboxylation to afford 1,4‐dihydroisoquinolin‐3(2H)‐one. Secondary alkylamines as well as nonprotected primary alkylamines underwent the transformation with high enantioselectivities (up to 98.5:1.5 e.r.) by using a newly developed chiral carboxylic acid as the sole source of chirality to achieve enantioselective C?H cleavage by a concerted metalation‐deprotonation mechanism.     

Anisotropic assembly of gold nanorods assisted by selective ion recognition of surface-anchored crown ether derivatives

Gold nanorods (NRs) mixed with crown ether derivatives exhibited the efficient and selective recognition of Na+ and K+ ions, which were detected by localized surface plasmon absorption in response to dispersed and aggregated gold NRs. Furthermore, in the aggregates preferential end-to-end or side-to-side assembly of NRs was observed which was dependent on the additive concentration.     

Oxygen K-edge fine structures of water by x-ray Raman scattering spectroscopy under pressure conditions

Fine structure of the oxygen K edge was investigated for water at ambient pressure, 0.16, 0.21, 0.27, 0.47, and 0.60 GPa using x-ray Raman scattering spectroscopy (XRS). Similarity in near-edge structures at 0.16 and 0.60 GPa suggests little difference in the electronic state of oxygen in the low-pressure and high-pressure forms of water. Yet, we observed significant variation of preedge structure of the XRS spectra with compression. The intensity of the preedge peak at 535.7 eV has a minimal value at around 0.3 GPa, indicating that the number of hydrogen bonding increases first and then decreases as a function of pressure.