A novel and convenient method for synthesis of carbamoyl and thiocarbamoyl phosphonates

A simple, efficient, and general method has been developed for the synthesis of carbamoyl and thiocarbamoyl phosphonic esters using CaCl₂ as an efficient Lewis base catalyst. Carbamoyl and thiocarbamoyl phosphonic esters were obtained in good yield (37%–65%) and purity under mild conditions by the reaction of diethyl phosphite with isocyanates and isothiocyanates in the presence of CaCl₂. This method is easy, rapid, and good‐yielding reaction for the synthesis of carbamoyl and thiocarbamoyl phosphonic esters. © 2009 Wiley Periodicals, Inc. Heteroatom Chem 20:250–253, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20538     

Density and viscosity of 1-butyl-3-methylimidazolium nitrate with ethanol, 1-propanol, or 1-butanol at several temperatures

Densities and viscosities of 1-butyl-3-methylimidazolium nitrate [Bmim][NO₃], and its binaries with alcohol (ethanol, 1-propanol, or 1-butanol) were measured at different temperatures. The densities and viscosities of pure ionic liquid were correlated successfully by empirical equations. The Vogel–Fulcher–Tammann equations can fit the experimental data of viscosities for pure IL. Excess molar volume and viscosity deviations were calculated for the binaries. The excess molar volumes have negative deviations from the ideal solution.     

A class of supported membranes: formation of fluid phospholipid bilayers on photonic band gap colloidal crystals

We report the formation of a new class of supported membranes consisting of a fluid phospholipid bilayer coupled directly to a broadly tunable colloidal crystal with a well-defined photonic band gap. For nanoscale colloidal crystals exhibiting a band gap at the optical frequencies, substrate-induced vesicle fusion gives rise to a surface bilayer riding onto the crystal surface. The bilayer is two-dimensionally continuous, spanning multiple beads with lateral mobilities which reflect the coupling between the bilayer topography and the curvature of the supporting colloidal surface. In contrast, the spreading of vesicles on micrometer scale colloidal crystals results in the formation of bilayers wrapping individual colloidal beads. We show that simple UV photolithography of colloidal crystals produces binary patterns of crystal wettabilities, photonic stopbands, and corresponding patterns of lipid mono- and bilayer morphologies. We envisage that these approaches will be exploitable for the development of optical transduction assays and microarrays for many membrane-mediated processes, including transport and receptor-ligand interactions.     

Synthesis of the proposed structure of mucoxin via regio- and stereoselective tetrahydrofuran ring-forming strategies

An enantioselective total synthesis of the proposed structure of mucoxin (1) is described. Mucoxin, an annonaceous acetogenin isolated from bioactive leaf extracts of Rollinia mucosa, is the first acetogenin containing a hydroxylated trisubstituted tetrahydrofuran (THF) ring. This natural product is a highly potent and specific antitumor agent against MCF-7 (breast carcinoma) cell lines (ED50 = 3.7 x 10(-3) microg/mL compared to adriamycin, ED50 = 1.0 x 10(-2) microg/mL). The total synthesis described herein features two regio- and stereoselective THF ring-forming reactions. The 2,3,5-trisubstituted THF portion (C13-C17) was accessed using a highly regioselective cyclization of a methylene-interrupted epoxydiol, and the 2,5-disubstituted THF ring (C8-C12) was conveniently assembled via a 1,2-n-triol cyclization strategy. The spectral data of the synthetic material and two of its diastereomers did not match the reported data for the natural product. On the basis of detailed spectroscopic analysis of the synthesized molecule, we reason that the spectral discrepancies are due to stereochemical misassignment of the natural product.     

Investigation of hydrazine addition to functionalized furans: synthesis of new functionalized 4,4′-bipyrazole derivatives

The addition of hydrazine to functionalized furans 2a-d leads to a variety of 4,4′-bipyrazoles 4a-c depending on the structure of the starting materials. In one example, compound 2c was first converted to an intermediate, furo[3,4-d]pyridazine 3c which was then transformed into 4,4′-bipyrazole 4c on reacting with hydrazine.     

A novel method for the separation of bis(alpha-hydroxyalkyl)phosphinic acid diastereoisomers via formation of novel cyclic phosphinic acids

The reaction of aromatic and aliphatic aldehydes with hypophosphorus acid under microwave irradiation was examined. The reaction gave a mixture of a racemic pair of bis(alpha-hydroxyalkyl)phosphinic acids and acetal derivatives from the corresponding bis(alpha-hydroxyalkyl)phosphinic acids of meso-stereochemistry in good yield. The difference in solubility in organic solvents due to polarity allowed us to readily separate these compounds. This method constitutes an easy, rapid, and good-yielding preparation and separation of bis(alpha-hydroxyalkyl) phosphinic acid diastereoisomers from simple starting materials using microwave irradiation.     

A signal subspace approach for modeling the hemodynamic response function in fMRI

Many fMRI analysis methods use a model for the hemodynamic response function (HRF). Common models of the HRF, such as the Gaussian or Gamma functions, have parameters that are usually selected a priori by the data analyst. A new method is presented that characterizes the HRF over a wide range of parameters via three basis signals derived using principal component analysis (PCA). Covering the HRF variability, these three basis signals together with the stimulation pattern define signal subspaces which are applicable to both linear and nonlinear modeling and identification of the HRF and for various activation detection strategies. Analysis of simulated fMRI data using the proposed signal subspace showed increased detection sensitivity compared to the case of using a previously proposed trigonometric subspace. The methodology was also applied to activation detection in both event-related and block design experimental fMRI data using both linear and nonlinear modeling of the HRF. The activated regions were consistent with previous studies, indicating the ability of the proposed approach in detecting brain activation without a priori assumptions about the shape parameters of the HRF. The utility of the proposed basis functions in identifying the HRF is demonstrated by estimating the HRF in different activated regions.     

Hydrangenone, a new isoprenoid with an unprecedented skeleton from Salvia hydrangea

Hydrangenone, a new heptacyclic isoprenoid with a 6/7/6/5/5 membered carbon ring skeleton, was isolated from the aerial parts of Salvia hydrangea. The structure was established by extensive NMR spectroscopic methods. The relative and absolute configuration of 1 was assigned by NOESY and X-ray crystallographic analysis and by comparison of experimental and calculated electronic circular dichroism (ECD) spectra. Compound 1 showed in vitro antiplasmodial activity, with an IC(50) value of 1.4 μM against P. falciparum. A plausible biosynthetic pathway of 1 was also proposed.     

A novel method for the one-pot conversion of carboxylic acids to N,N-dimethylamides

A simple, efficient, and new method has been developed for the preparation of N,N-dimethylamides from carboxylic acids. As described below, treatment of a variety of aromatic carboxylic acids with N,N-dimethylsulfamoyl imidazole or N,N-dimethylsulfamoyl chloride in the presence of a mixture of methanesulfonic acid/phosphorus pentoxide (2:1, v/w) proceeded effectively to afford the corresponding N,N-dimethylamides in moderate to good yields. This method is easy, rapid, and good yielding for the synthesis of N,N-dimethylamides from carboxylic acids.     

Nano-sized layered aluminium or zinc-manganese oxides as efficient water oxidizing catalysts

Nano-sized layered aluminium or zinc-manganese oxides were synthesized and characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction spectrometry, dynamic light scattering and atomic absorption spectroscopy. These oxides showed efficient water oxidizing activity in the presence of cerium(IV) ammonium nitrate as a non-oxo transfer oxidant. Amounts of dissolved manganese, zinc or aluminium, and water oxidation activities of these oxides were reported and compared with other manganese oxides. A mechanism for oxygen evolution and possible roles for zinc or aluminium ions are also proposed.