A new method for the spectrophotometric determination of pertechnetate with tris(1,10-phenanthroline)iron(II) ion

A new spectrophotometric determination of technetium has been developed by means of the solvent extraction of tris(1,10-phenanthroline)iron(II) ([Fe(phen)₃ ²⁺]) with pertechnetate into nitrobenzene. The concentration of technetium can be determined by measuring the characteristic absorbance at 516 nm (=11,700M^–1·cm^–1) in the organic phase. An important feature of the proposed method is that the concentration of pertechnetate can be determined without complicated processes such as the reduction of pertechnetate and the subsequent formation of a colored chelate.     

Nucleosides. CXXXV. Synthesis of some 9-(2-deoxy-2-fluoro-beta-D-arabinofuranosyl)-9H-purines and their biological activities

Seven purine nucleosides containing the 2'-deoxy-2'-fluoro-beta-D-arabinofuranosyl moiety were synthesized and tested for their antitumor activity. Direct condensation of 3-O-acetyl-5-O-benzoyl-2-deoxy-2-fluoro-D-arabinofuranosyl bromide (1) with N6-benzoyladenine in CH2Cl2 followed by saponification of the product afforded the adenine nucleoside (I, 2'-F-ara-A). Deamination of I with NaNO2 in HOAc gave the hypoxanthine analogue (II, 2'-F-ara-H). The 6-thiopurine nucleoside (III, 2'-F-ara-6MP) was prepared by condensation of 1 with 6-chloropurine by the mercury procedure followed by thiourea treatment and saponification of the product. Methylation of III gave the 6-SCH3 analogue (IV). Raney Ni desulfurization of III afforded the unsubstituted purine nucleoside (V, 2'-F-ara-P). Condensation of 1 with 2-acetamido-6-chloropurine by the silyl procedure afforded the protected 2-acetamido-6-chloropurine nucleoside which served as the precursor for both the guanine and 6-thioguanine nucleosides (VI, 2'-F-ara-G and VII, 2'-F-ara-TG, respectively). Thus, alkaline hydrolysis of the precursor gave VI. Thiourea treatment prior to alkaline hydrolysis gave VII. The new nucleoside, 2'-F-ara-G (VI) is found to be selectively toxic to human T-cell leukemia CCRF-CEM.     

Addition of chlorodisilanes to 1,3-butadienes in the presence of tetrakis(triphenylphosphine)palladium(0). A facile route to (Z)-1,4-bis(chlorosilyl)but-2-enes

In the presence of a catalytic amount of tetrakis(triphenylphosphine)palladium(0), chlorodisilanes of type Me_nSi₂Cl_6-n (n  0, 2, 3 and 4) add to 1,3-butadienes to give (Z)-1,4-bis(chlorosilyl)but-2-enes.     

Synthetic studies on indoles and related compounds. XXXI. Chemical confirmation of the synthetic route for the benz[f]indole skeleton and its application

To confirm the structure of ethyl 9-methoxybenz[f]indole ( 8a ) prepared from ethyl pyrrole-2-carboxylate ( 4 ) via a new synthetic route, the following chemical correlation work was performed. Ethyl 9-methoxybenz[f]in-dole ( 8a ) was converted to 1-benzyl-3-methyl-5,6,7,8-tetrahydrobenz[f]indole ( 25 ), which was alternatively and authentically synthesized from ethyl 3-methylpyrrole-2-carboxylate ( 11 ). On the basis of the established route to the benz[f]indole nucleus, two representative benz[f]indoles, benz[f]indole ( 1 ) and 4,9-dioxobenz[f]indole ( 26 ) were synthesized.     

Radiation-induced polymerization of glass-forming systems. VII. Polymerization in supercooled state under high pressure

Radiation-induced polymerization of glass-forming monomers such as 2-hydroxyethyl methacrylate and glycidyl methacrylate under high pressure was studied. The glass transition temperature of these monomers was heightened by increased pressure. The temperature dependence of polymerizability showed a characteristic relation; similar to those in supercooled-phase polymerization under normal pressure, that had a maximum at T_v which shifted to higher levels of temperature as well as to T_g under high pressure. Polymerizability in the supercooled state also increased under increased pressure.     

Electron spin echo study of long-lived radicals which cause mutation in gamma-ray irradiated mammalian cells

Long-lived radicals, produced by gamma-ray irradiation of mammalian cells at room temperature, cause mutation and morphological transformation in the cells. The local environment near the long-lived radicals in irradiated cells was investigated here by the analysis of electron spin echo envelope modulation (ESEEM) spectra. The number of hydrogen (deuterium) atoms surrounding the long-lived radical, which may correspond to the number of water molecules, was estimated roughly as one or two. It is postulated that the long-lived radicals are generated in the interior of biopolymers. The radicals are not produced by the reaction of OH radicals, but mainly by the decomposition of biopolymer which absorbed directly the energy of the ionizing radiation.