Cyanide-Free One-Pot Synthesis of Methacrylic Esters from Acetone

Methacrylic esters, represented by methyl methacrylate (MMA), are widely used as commodity chemicals. Here, the one-pot synthesis of methacrylic esters from acetone, a haloform and alcohols in the presence of an organic base is described. Using DBU as the organic base for the reaction of acetone, chloroform and methanol in acetonitrile afforded MMA in 66 % yield. When the solvent was replaced by benzonitrile, the product MMA was successfully purified by distillation. Applicability of this process to various alcohols was also investigated to show ethyl, phenyl, CF₃CH₂, and n-C₆F₁₃CH₂CH₂ esters were obtained in moderate yields. The use of bromoform instead of chloroform resulted in the improvement of the yield, for example, methyl and n-C₆F₁₃CH₂CH₂ esters up to 81 and 70 %, respectively. The reaction with deuterated starting materials acetone-d₆ and MeOH-d₄, with DBU in acetonitrile afforded deuterated MMA (MMA-d₈) in 70 % yield.     

An efficient conversion of 1-abietic acid to (+)−3-deoxyaphidicolin

The first total synthesis of (+)?3-deoxyaphidicolin, a selective inhibitor of eukaryotic DNA polymerase α, has been completed efficiently and stereoselectively starting from 1-abietic acid.     

Inclusion behavior of thiacalix[4]arenetetrasulfonate toward water-miscible organic molecules studied by salting-out and X-ray crystallography

[reaction: see text] Inclusion ability of thiacalix[4]arenetetrasulfonate (TCAS) toward water-miscible organic molecules such as alcohols, ketones, cyclic ethers, and so on was studied by salting-out of the inclusion complex. NMR spectra of the recovered precipitates showed size selectivity to include the guest molecules. X-ray crystallographic analyses of TCAS salts including acetone and 1,4-dioxane suggested that guests are retained with the aid of cation coordination and H-bonding.     

Effectiveness of taurine in protecting biomembrane against oxidant

The effect of taurine in protecting biomembrane attacked by hypochlorous acid (HOCl) was examined using canine erythrocytes which had been pre-treated with HOCl. In the treatment, most of the HOCl was consumed as a result of its reaction with a number of electrophilic substances, such as free amino groups (-NH2) in the membrane, whereas hemoglobin inside the cells was not oxidized. The lysis of HOCl-treated erythrocytes was dependent on the concentration of HOCl and on the incubation time at 37 degrees C. Taurine inhibited the lysis at 37 degrees C in a dose dependent manner. During the incubation of HOCl-treated erythrocytes with taurine, an appreciable amount of monochlorotaurine (TauNHCl) was detected in the supernate. This suggests that taurine might remove the oxidized chlorine from HOCl-treated erythrocytes, resulting in the production of TauNHCl. The effect of taurine on the removal of Cl+ moiety was further examined using Sepharose gel with free amino groups. Taurine removed Cl+ moiety from HOCl-treated Sepharose gel, and the yield of TauNHCl depended on the concentration of taurine and the incubation time. These results indicate that taurine might inhibit the hemolysis by scavenging the oxidized chlorine moiety from the HOCl-treated erythrocytes. Inhibition of the HOCl-induced hemolysis was also observed with other amino acids.(ABSTRACT TRUNCATED AT 250 WORDS)     

Radiation-induced emission from golden hamster embryo cells

Emission from high-energy-electron-irradiated golden hamster embryo (GHE) cells has been studied over the temperature range 12–300 K both by a one-shot-single-photon-counting method and by photocurrent measurements with an oscilloscope. Emission from the irradiated phosphate buffered saline (PBS) also has been studied. The emission spectra from PBS at 12 and 77 K show a maximum around 330 and 380 nm, respectively, which are the same spectra as those from irradiated pure H₂O. The emission from irradiated GHE consists of the new band at 480 nm in addition to the emission from H₂O. The 480 nm emission is observed at the temperature range of 12–300 K, though the emission at 300 K is much lower than that at low temperature. The 480 nm emission is ascribed to the transition from excited organic substances in GHE cells. The intensity of 480 nm emission at 300 K increases linearly with increasing irradiation-dose in the range of 11–600 Gy.     

Staggered polarization of vertex models withU_q (\widehat{sl(}n))-Symmetry

In this paper we give an explicit formula for level 1 vertex operators related to as operators on the Fock spaces. We derive also their commutation relations. As an application we calculate with the vector representation of , thereby extending the recent work on the staggered polarization of the XXZ-model.     

Three new quassinoids,ailantinol E,F, and G,from Ailanthus altissima

Three new quassinoids, ailantinol E (1), ailantinol F (2), and ailantinol G (3), and related compounds were isolated from Ailanthus altissima grown in Taiwan. Their structures were elucidated from spectral evidence. Each new quassinoid was evaluated for its antitumor promoting effects against Epstein-Barr virus early antigen activation introduced by 12-O-tetradecanoylphorbol-13-acetate in Raji cells. The new quassinoids were found to show potent activity without showing any cytotoxicity. The screening for inhibitors against nitric oxide donor action was also conducted using the new quassinoids and some standard samples.     

Radical-initiated homopolymerization and copolymerization of ethyl α-hydroxymethylacrylate

Ethyl α-hydroxymethylacrylate (EHMA) was synthesized and homopolymerized in bulk and in solution. The poly(EHMA) is readily soluble in alcohol, acetone, tetrahydrofuran, and methylene chloride at room temperature. Intramolecular lactone formation occurred when poly(EHMA) was heated to 180–230°C. The kinetics of EHMA homopolymerization was investigated in ethyl acetate, using α,α′-azobisisobutylonitrile as an initiator. The rate of polymerization R_p was expressed by R_p = k[AIBN]^0.50[EHMA]^1.4 and the overall activation energy was calculated as 71.9 kJ/mol. Kinetic constants for EHMA polymerization were obtained as follows: k_p/k = 0.17L^0.9mol^?0.9s^?0.5; 2fk_d = 1.5 × 10^?5 s^?1. The relative reactivity ratios of EHMA(M₂) copolymerization with styrene (r₁ = 0.472, r₂ = 0.564) in ethyl acetate were obtained. Applying the Q-e scheme led to Q = 0.84 and e = 0.35 for EHMA.