Syntheses of potential metabolites of a potent kappa-opioid receptor agonist, TRK-820

Chemical syntheses of three kinds of potential metabolites of TRK-820, a potent kappa-opioid receptor agonist, were described. One of the potential metabolites 2, 17-N-dealkylated TRK-820, was synthesized starting from noroxycodone through 8 steps in 21% total yield. Glucuronidation of intermediate 10 and compound 1, the free base of TRK-820, was carried out stereoselectively to give 3-O-beta-D-glucuronides 15 and 16 in good yields, respectively. Syntheses of potential conjugated metabolites 3 and 4 were accomplished through 10 steps and 2 steps in 11% and 43% total yields, respectively. Among the potential metabolites of TRK-820, compounds 2 and 4 were identified as metabolites in human hepatocytes. The results of pharmacological studies of compounds 2, 3, and 4 are described.     

Optically active electrochromism in polyanilines

The electrochemically driven control of the natural optical activity of polyanilines bearing chiral camphorsulfonic acid is reported. Aniline was polymerized in the presence of camphorsulfonic acid by oxidative electrochemical polymerization in water to afford polyanilines containing (+)- or (−)-camphorsulfonic acid. This research elucidated that the polymerization, with cyclic voltammetry scanning up to 1.1 V, produced consistent optically active polyanilines. The polyaniline films thus prepared showed intense and tunable optical activity based on electrochemical reduction/oxidation in a 0.1 M sulfuric acid aqueous solution. The circular dichroism and optical rotation angle of the polymer were tunable by the appropriate adjustment of an externally applied potential as a form of optical modulation. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2085–2090, 2007     

Catalytic Reduction of Dinitrogen into Ammonia and Hydrazine by Using Chromium Complexes Bearing PCP-Type Pincer Ligands**

A series of chromium-halide, -nitride, and -dinitrogen complexes bearing carbene- and phosphine-based PCP-type pincer ligands has been newly prepared, and some of them are found to work as effective catalysts to reduce dinitrogen under atmospheric pressure, whereby up to 11.60 equiv. of ammonia and 2.52 equiv. of hydrazine (16.6 equiv. of fixed N atom) are produced based on the chromium atom. To the best of our knowledge, this is the first successful example of chromium-catalyzed conversion of dinitrogen to ammonia and hydrazine under mild reaction conditions.     

Photocatalytic degradation of dichloroacetyl chloride adsorbed on TiO<Subscript>2</Subscript>

Dichloroacetyl chloride (DCAC) attracted our attention as an intermediate product of the photocatalytic degradation of trichloroethylene (TCE). The adsorption and photocatalytic reaction of DCAC on TiO₂ have been investigated by FTIR spectroscopy. The influence of the surface structure of several TiO₂s on the reaction mechanism was discussed in order to understand the complete degradation mechanism of TCE as well as DCAC. DCAC was transformed into dichloroacetic acid (DCAA) on the relatively hydrophobic TiO₂ surface by the small amount of the water molecules weakly adsorbed on the surface. This DCAA was degraded to phosgene, CO₂, and CO during UV irradiation. For the hydrophilic TiO₂, DCAC was mainly transformed into the dichloroacetate anion. UV irradiation allowed this species to produce chloroform in addition to phosgene, CO₂, and CO. It is suggested that DCAC easily reacts with the Ti–OH group on the hydrophilic TiO₂ and forms the bidentate titanium chelate of dichloroacetate, which efficiently degrades into chloroform.     

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).     

Solvent effect on fluorescence spectra of a spirooxazine

Fluorescence and excitation spectra of spironaphthoxazine (SNO) in various solvents have been investigated systematically. The fluorescence in low-polar solvents normally originated from SNO in the excited state. In protic high-polar solvents, fluorescence from an excited intermediate species (X^* _h) relaxed from a part of the excited SNO by breaking a C-O bond in the oxazine ring was also observed. It has been found that a ground-state intermediate species (X_s), transformed from a part of ground-state SNO, is directly excited to its excited state (X_s ^*), which displays fluorescence in aprotic high-polar solvents.