Some aspects of nitroxide-mediated living radical polymerization of N-(p-vinylbenzyl)phthalimide

The free radical polymerization of N-(p-vinylbenzyl)phthalimide (VBP) “initiated” with the adduct of 2-benzoyloxy-1-phenylethyl and TEMPO (BS-TEMPO) or TEMPO-terminated polystyrene (PS-TEMPO) in N,N-dimethylformamide (DMF) at 125 °C was found to proceed in a living fashion, providing low-polydispersity PVBP and block copolymers of the type PS-b-PVBA, where TEMPO is 2,2,6,6-tetramethylpiperidinyl-1-oxy. Unlike TEMPO-mediated styrene polymerization, the polymerization rate slightly but distinctly depended on the adduct concentration, which was interpretable as a pre-stationary behavior. The hydrolysis of those polymers gave poly(p-aminomethylstyrene) (PAMS) and PS-b-PAMS, and further treatment of the block copolymer with hydrogen chloride provided an amphiphilic block copolymer. The polymeric amphiphile was used as an emulsifier in emulsion polymerization to produce a positively charged polymeric microsphere.     

Thermal behavior of ground mixtures of heptakis (2,6-di-O-methyl)-β-cyclodextrin and benzoic acid

Characterization of an inclusion complex prepared from amorphous ground mixtures of heptakis (2,6-di-O-methyl)--cyclodextrin (DMCD) and benzoic acid was carried out by a sealed heating method. The formation of the crystalline inclusion complex and the variation in physicochemical properties of the ground mixture were investigated as a function of heating temperature. On the basis of X-ray diffractometry and Fourier transform infrared spectroscopy, the crystallization of the ground mixture was confirmed to take place at about 135°C. The crystallization temperature was shifted to lower temperatures and the bound molar ratio of benzoic acid to DMCD increased as the mixing molar ratio of benzoic acid to DMCD was raised.Tsumura & Co., 3586 Yoshiwara, Amimachi, Inashikigun, Ibaraki 300-11, Japan.     

First catalytic asymmetric hydrophosphonylation of cyclic imines: Highly efficient enantioselective approach to a 4-thiazolidinylphosphonate via chiral titanium and lanthanoid catalysts

The catalytic and enantioselective hydrophosphonylation of a cyclic imine, namely the 3-thiazoline 1, is described. We have discovered a highly efficient enantioselective de novo approach to the pharmaceutically interesting 4-thiazolidinylphosphonate 2 using either titanium or lanthanoid chiral catalysts, which gives excellent enantiomeric purities (up to 98 %ee) and high chemical yields.     

Di-isopropyl fluorophosphate electrode based on squid nerve tissue

Di-isopropyl fluorophosphatase is contained in the giant axon of squid nerve tissue. This tissue can be coupled with a fluoride ion-selective electrode to produce an electrode selective to di-isopropyl fluorophosphate. The semilogarithmic calibration curve at pH 7.1 is linear over the range 2 × 10^?6?7 × 10^?3 M (RSD < 3% ) with a slope of about 44 mV/decade. The detection limit is 8 × 10^?6 M. The electrode lifetime (with constant response characteristics) is about 16 days.     

Mechanism of formation of iron(II) complexes with pentadentate ligands via C-C bond formation between trans-[Fe(2,4-bis(2-pyridylmethylimino)pentane)(MeCN)2]ClO4]2.MeCN and various nitriles

The order of relative reactivity of nitriles for the formation of Fe(II) complexes (2s) with 3-(1-alkyl(or aryl)methyl)-1-imino-2,4-bis(2-pyridylmethylimine)(L(2)s) from that with 2,4-bis(2-pyridylmethylimono)pentane (L1), trans-[FeL(1)(MeCN)(2)][ClO(4)](2).MeCN (1), and various nitriles has been determined based on the following order: C(6)F(5)CN > 3,4-difluorobenzonitrile > 4-fluorobenzonitrile > C(6)H(5)CN > C(6)H(5)CH(2)CN > C(2)H(5)CN > MeCN > Me(2)CHCN >Me(3)CN. An iron(II) complex with L1 in a cis-configuration was prepared as the ternary complex [FeL(1)(bpy)][ClO(4)](2).1.5MeNO(2).0.5H(2)O, 3a (bpy = bipyridine). Compounds 2s and 3a undergo enantiomeric interconversion with an activation energy of ca. 60 kJ mol(-1).     

Ground state of the Si(0 0 1) surface revisited—is seeing believing?

The stable structure of clean Si(0 0 1) surface around 100 K is the c(4 × 2) arrangement constructed by buckled dimers. This structure was widely accepted as the ground state in 1990’s. The view was challenged at the beginning of 2000’s by the observations of a p(2 × 1) structure below 20 K with scanning tunneling microscopy (STM). Recent experimental studies confirm that the dimer is buckled below 30 K. Large tip–surface interaction, and/or tunneling current induced dynamical effect are now experimentally evident in the STM images at low temperatures. Moreover, a current induced structure transformation is discovered below 40 K even in the study by low energy electron diffraction. Dynamical electronic and vibrational effects are theoretically studied for accounting the observation of a p(2 × 1) structure below 20 K.     

A convenient preparation of 4,8-dimethoxy-3-substituted-2(1H)-quinolones by an electrophilic reaction through base-induced deprotonation and its synthetic application for the synthesis of new alkaloids, 3,4,8-trimethoxy-2(1H)-quinolone and 3-formyl-4,7,8-trimethoxy-2(1H)-quinolone(glycocitridine)

Some 4,8-dimethoxy-3-substituted-2(1H)-quinolones were prepared by electrophilic reaction of 4,8-dimethoxy-2(1H)-quinolone with electrophiles in the presence of n-butyllithium-N,N,N',N'-tetramethylethyl-enediamine in fairly good yields. This present method was successfully applied for the synthesis of two new alkaloids bearing the 4,8-dimethoxy-2(1H)-quinolone skeleton.     

Synthesis of 3-Diaminomethylene-2(3 H )-furanones by Reaction of 2-Amino-4,5-dihydro-3-furancarboxamides with Amines

 The reaction of 2-amino-4,5-dihydro-3-furancarboxamides with morpholine in the presence of acetic acid in pyridine or under the influence of ammonium acetate gave the corresponding 3-diaminomethylene-4,5-dihydro-2(3H )-furanones; 4,5-dihydro-2-morpholino-3-furancarboxamides were not isolated. One of the former reacted with benzylamine to give (E )- and (Z )-3-(amino-(benzylamino)-methylene)-4,5-dihydro-4-phenyl-2(3H )-furanones and 2-benzylamino-4,5-dihydro-4-phenyl-3-furancarboxamide.     

Stereochemical regulation of polypropylenes prepared with various Ziegler-Natta catalysts

The 220-MHz proton magnetic resonance and infrared spectra of stereoregular polypropylenes polymerized with a number of Ziegler-Natta catalysts and isotactic polymers of low molecular weight obtained by thermal degradation of a highly isotactic polypropylene were measured in an attempt to obtain some information on the local regularity. The fraction of thermally degraded polymer soluble in diethyl ether shows stereorandomness (tactie sequence length is quite short), and the portion soluble in n-pentane has stereoblock character. The results so obtained provide strong evidence that racemic dyads of whole polymer consist of two models of racemic dyad isolated and racemic dyads in groups. The polymers prepared with vanadium catalyst systems show stereorandom character and these polymers have \documentclass{article}\pagestyle{empty}\begin{document}$\hbox{-\hskip-1pt-}\hskip-4pt({\rm CH}_2 \rlap{--} )$\end{document} groups formed by two propylene units in a tail-to-tail linkage. Syndiotactic polypropylene has head-to-head and tail-to-tail arrangements of two propylene units and this is the origin of randomness of syndiotacticity.     

A Study of the Application of Photoexcited TiO2 Particle to Cancer Treatment

The purpose of the present paper is to introduce such a new application of photoexcited TiO₂ to the area of biology that has been investigated in our laboratory. The behavior of cultured celles on the photoexcied TiO₂ electrode surface and the cell killing effect of photoexcited TiO₂ particles are described. And the possible application of this cell killing effect of photoexcited TiO₂ particles to cancer treatment is discussed.