bluuebunny/crossref_metadata_2025 huggingface dataset:
Coevaporation of Cu2ZnSnSe4 thin films
Authors: Redinger Alex , Siebentritt Susanne
Published: September 2010

Cu 2 ZnSnSe 4 thin films grown by coevaporation are investigated in a wide temperature range and for different Se partial pressures during growth. At temperatures higher than 350 °C Sn is re-evaporating as SnSe from the surface whereas Zn is lost at temperatures higher than 430 °C. Moreover the Se partial pressure dramatically changes the Zn and Sn concentrations in the resulting film. Interrupted processes at 380 °C show that single-stage coevaporation intrinsically induces a secondary phase at the substrate/film interface.
Charge-injection induced magnetism and half metallicity in single-layer hexagonal group III/V (BN, BP, AlN, AlP) systems
Authors: Wu Menghao , Zhang Zhuhua , Zeng Xiao Cheng
Published: September 2010

Based on the first-principles calculations, we predict that strong ferromagnetism and half metallicity can be induced via charge injection in single-layer hexagonal boron nitride (BN) and BN nanoribbons. This phenomenon can be understood based on the Stoner criterion and the relationship between induced magnetic moment and charge density. Other group-III/V two-dimensional honeycomb systems such as boron phosphide (BP), aluminum nitride (AlN), and aluminum phosphide (AIP) exhibit similar ferromagnetic behavior upon charge injection. Like BN, the single-layer hexagonal AlN can be converted to a half metal at certain positive charge states.
Hydrogen related defect complexes in ZnO nanoparticles
Authors: Senthilkumar K. , Tokunaga M. , Okamoto H. , Senthilkumar O. , Fujita Y.
Published: September 2010

Hydrogen related local vibrational modes (LVMs) of ZnO nanoparticles have been studied using Fourier transform infrared spectroscopy and Raman spectroscopy in as prepared and high temperature annealed samples. The obtained experimental results confirm the presence of cationic vacancies (VZn) in addition to unintentional hydrogen doping and their complex defects such as VZn–Hi and VZn–HO. After high temperature annealing, hydrogen related LVMs and multiphonon modes disappear. The presence of these complex defects determines the nonradiative and multiphonon recombination processes in the band gap of ZnO due to carrier trapping at deep levels.
Photovoltaic nanopillar radial junction diode architecture enhanced by integrating semiconductor quantum dot nanocrystals as light harvesters
Authors: Güzeltürk Burak , Mutlugün Evren , Wang Xiaodong , Pey Kin Leong , Demir Hilmi Volkan
Published: September 2010

We propose and demonstrate colloidal quantum dot hybridized, radial p-n junction based, nanopillar solar cells with photovoltaic performance enhanced by intimately integrating nanocrystals to serve as light harvesting agents around the light trapping pillars. By furnishing Si based nanopillar photovoltaic diodes with CdSe quantum dots, we experimentally showed up to sixfold enhancement in UV responsivity and ∼13% enhancement in overall solar conversion efficiency. The maximum responsivity enhancement achieved by incorporation of nanocrystals in the nanopillar architecture is found to be spectrally more than four times larger than the responsivity enhancement obtained using planar architecture of the same device.
Multiple-level threshold switching behavior of In2Se3 confined in a nanostructured silicon substrate
Authors: Lee Jae Young , Sun Ke , Li Biyun , Xie Ya-Hong , Wei Xinyu , Russell Thomas P.
Published: September 2010

We report the experimental observation of an intriguing behavior of multiple-level threshold switching of Si–In2Se3 heterojunction devices consisting of high-density arrays of sharp points of nanometer radius of curvature. Comparison with devices of similar junction area but without the sharp points shows that the multiple-level switching behavior is unique to devices with junctions consisting of sharp points.
Band offsets of semiconductor heterostructures: A hybrid density functional study
Authors: Wadehra Amita , Nicklas Jeremy W. , Wilkins John W.
Published: September 2010

We demonstrate the accuracy of the Heyd–Scuseria–Ernzerhof (HSE06) hybrid functional for computing the band offsets of semiconductor alloy heterostructures. The highlight of this study is the computation of conduction band offsets with a reliability that has eluded standard density functional theory. A special quasirandom structure models an infinite random pseudobinary alloy for constructing heterostructures along the (001) growth direction. Our results for a variety of heterostructures establish HSE06’s relevance to band engineering of high-performance electrical and optoelectronic devices.
Micropump based on liquid marbles
Authors: Bormashenko Edward , Balter Revital , Aurbach Doron
Published: September 2010

A micropump based on a pair of liquid marbles coated with various powders and connected with a capillary tube is presented. The idea of the micropump is based on the difference of the Laplace pressures in the marbles. The initial stream was supported by the pressure instability developed under water overflow. The reported experiments validate the concept of the effective surface tension of liquid marbles. The micropump could be used for precise delivery of small quantities of liquids, the design of microreactors and microfluidics applications.
Disordered antireflective nanostructures on GaN-based light-emitting diodes using Ag nanoparticles for improved light extraction efficiency
Authors: Song Young Min , Choi Eun Sil , Park Gyeong Cheol , Park Chang Young , Jang Sung Jun , Lee Yong Tak
Published: September 2010

In this study, we demonstrate GaN light-emitting diodes (LEDs) with antireflective subwavelength structures (SWS) for enhanced light extraction efficiency. To eliminate the internal Fresnel reflection, SWS were fabricated on an indium-tin-oxide (ITO) surface using an overall dry etch process of Ag nanoparticles. The average size of the Ag nanoparticles was carefully chosen by theoretical calculation of the reflective diffraction efficiency using a rigorous coupled-wave analysis (RCWA) method. Improvement in light output power of ∼30.2% was achieved for the fabricated ITO SWS LEDs compared to conventional LEDs, with no significant increase in the forward voltage.
The Nitration of 2,3,4-Tribromo-5,6-dimethylphenol and 3,4-Dibromo-2,5,6-trimethylphenol
Authors: Chambers MV , Hartshorn MP , Robinson WT , Vaughan J
Published: September 2010

The nitrations of 2,3,4-tribromo-5,6-dimethylphenol (9) and 3,4- dibromo-2,5,6-trimethylphenol (10) with fuming nitric acid in acetic acid give 2,5,6-trinitrocyclohex-3-enones in addition to 6-hydroxy-2,5-dinitrocyclohex-3-enones. X-ray crystal structure determinations are
reported for the trinitro ketones (21) and (22), and the hydroxy dinitro ketones (23) and (24).
Proton-Coupled Transport of Ammonia in Aqueous Hydrochloric Acid
Authors: Leaist DG
Published: September 2010

Ternary diffusion in aqueous ammonia + hydrochloric acid solutions has been measured at 25°C. It is
shown that the transport coefficients can be successfully predicted from the mobilities of H+, Cl -, NH4+, and un- ionized ammonia species present in the solutions. When an ammonia concentration gradient is prepared in a solution containing excess acid, the region of the solution with the higher ammonia concentration is depleted in H+ by formation of ammonium ion: NH3+H+
↔ NH4+. As highly mobile H+ diffuses up the ammonia gradient, there is counterflow of NH4+ in order to maintain electroneutrality . This mechanism leads to rapid diffusion of the ammonia component as NH4+. Binary diffusion coefficients of aqueous ammonia have also been measured. Extrapolation gives 2.08(�0.01) × 10-2m2 s-1 for the limiting diffusion coefficient of un-ionized ammonia, a value 6% greater than the limiting diffusion coefficient of the ammonium ion.
Design, Synthesis and Testing of Transition State Analogues of Alanine Racemase as Antibacterials
Authors: Leung DK , Andrews PR , Craik DJ , Iskander MN , Winkler DA
Published: September 2010

Transition state analogues have been designed for alanine racemase , an important enzyme target for the development of bacterial cell wall inhibitors. These analogues are based on the transition state structure obtained from MINDO/3 calculations on the reaction pathway of a model alanine racemization . A number of analogues have been synthesized and are shown to have weak anti-bacterial activity, but results from microbiological assays indicate that their antibacterial activity is not due to inhibition of alanine racemase . Subsequent n.m.r .studies have shown that they are unstable in aqueous environments. Formaldehyde has been identified as one of the degradation products, and the likely source of antibacterial activity.
Lanthanide-Induced Shifts in the 13C N.M.R. Spectra of epi-Inositol and Some Anhydrohexoses. The Anomalous Behaviour of the Heavy Lanthanides
Authors: Angyal SJ , Littlemore L , Gorin PAJ
Published: September 2010

The shifts induced in the 13C n.m.r . spectrum of epi-inositol by the addition of various lanthanide ions have been determined and have been analysed in terms of contact and pseudocontact interactions. The behaviour of the three heavy lanthanides was found to be anomalous, probably owing to their smaller ionic radii and their lesser extent of hydration. Similar measurements have also been carried out on four 1,6- anhydro-β-D-hexopyranoses.
Insect Moulting Hormones. LV. Experiments Directed Towards the Synthesis of Non-steroidal Ecdysone Analogues
Authors: Bergamasco R , Horn DHS , Nearn RH , Wilkie JS
Published: September 2010

Exploratory studies aimed at the synthesis of the non-steroidal ecdysone analogue (4aR,7S,8aR,-1′RS,4′R)-7-hydroxy-3-(1′-hydroxy-4′,8′- dimethylnonyl )-4a-methyl-4a,5,6,7,8,8a-hexahydronaphthal-en- 1(4H)-one (3) have led to in efficient method of joining the cyclic and side-chain synthons by reacting the vinylogous ester (4a) with 1-lithio-4,8-dimethyl-1,1-bis( methylthio ) nonane (12) to yield (4′RS)-3- [4′,8′-dimethyl-1′,1′-bis( methylthio ) nonyl ]-5,5-dimethylcyclohex-2-en-1-one (13). This thioacetal on reaction with boron trifluoride etherate and mercuric oxide afforded, quantitatively, the diketone (4′RS)-3-(4′,8′-dimethyl-1′-oxononyl)-5,5-dimethylcyclohex-2-en-1-one (14) which was selectively reduced in 85% yield to the required model compound (4′RS)-3-(1′-hydroxy-4′,8′-dimethylnonyl)-5,5-dimethylcyclohex-2-en-1-one (15).
Nitration of 2,3,4,6-Tetramethylphenol and 1,2,3,5-Tetramethylbenzene
Authors: Hartshorn MP , Readman JM , Robinson WT , Vaughan J
Published: September 2010

Nitration of 1,2,3,5-tetramethylbenzene (2a) with fuming nitric acid gives the tetramethylnitrobenzene (22), products of side-chain modification (23)-(27), the rearranged 6,6-dimethylcyclohexenones (8), (28), (29) and (30), and 2,3,4,6-tetramethyl ketone derivatives (10)- (13), (31) and (32). Reaction of 2,3,4,6-tetramethylphenol (7) with nitrogen dioxide gives the hydroxy dinitro ketone (9) in addition to the trinitrocyclohexenones (11)-(14) and (19). X-ray crystal structures are reported for compounds (11), (19), (28), (29), (30) and (32). 1H n.m.r ./stereochemistry correlations are reported for some 2,5-dinitro- and 2,5,6-trinitro-cyclohex-3-enones.
Pterins. X. A New Preparation of 6-Hydroxymethylpterin from 6-Methylpterin
Authors: Waring P , Armarego WLF
Published: September 2010

6-Hydroxymethylpterin was prepared in c. 80% overall yield via 2- acetamido-6-methylpteridin-4(3H)-one, oxidation with lead tetraacetate to 2-acetamido-6-acetoxymethylpteridin-4(3H)-one and hydrolysis. The 2-acetamido-6-methylpterin was prepared isomerically pure by acetylation of a mixture of 6- and 7-methylpterin prepared by condensation of 2,5,6-triaminopyrimidin-4(3H)-one with methylglyoxal at 0-5°. Under these conditions the ratio of 6-methyl- to 7-methylpterin is considerably improved (9 : 1).
Electrochemical Phase Diagrams for the Fe/S/H2O System under Geothermal Conditions
Authors: Pound BG , Wright GA , Sharp RM
Published: September 2010

Previously published electrochemical phase (potential-pH) diagrams for the Fe/S/H2O system at elevated temperatures are assessed. It is concluded that the potential-pH equations derived by Biernat and Robins1 can be used to provide reliable diagrams over the temperature range 298-573 K. These equations were used to derive a set of diagrams relevant to geothermal fluids in general terms, so that the corrosion products of iron and ferrous alloys immersed in these fluids may be predicted. In addition, diagrams are presented for geothermal fluids in the Broadlands and Wairakei fields in New Zealand. The significant changes in the E-pH diagrams as the temperature increases over the range 298-573 K are that the region of stability for Fe(OH)3- widens and the regions of stability for FeS2 and Fe3O4 and, at higher temperatures, FeS, shrink in size.
Aluminium(III) and Iron(III) 1,2-Diphenolato Complexes: a Potentiometric Study
Authors: Kennedy JA , Powell HKJ
Published: September 2010

The equilibrium reactions between aluminium(III) and the phenols catechol (LH2), protocatechuic acid (LH3) and catechin (LH4), and between iron(III) and protocatechuic acid have been studied by potentiometric titration in aqueous solution, I 0.10M ( KCl ), 25°C. Stability constants are reported for the mononuclear diphenolato complexes AlLHn-2, Al(LHn-2)2and Al(LHn-2)3, and the hydroxo complexes Al(OH)LHn-2 and Al(OH)(LHn-2)2, n = 2 ( catechol ) or 4 ( catechin ). For protocatechuic acid, the carboxylate -coordinated species lLH22+ and the species AlLH + (carboxyl- protonated ) are also postulated. Analogous species were characterized for the iron(III)- protocatechuic acid system. Stoichiometric end-points were obtained only if an excess of ligand was used (L/M > 4). Monomeric and polymeric aluminium- hydroxo species and ternary metal- ligand - hydroxo species were found to be unimportant under the experimental conditions employed.
Boron, Trichloride as a Selective Demethylating Agent for Hindered Ethers: a Synthesis of the Phytoalexins α- and Β-Pyrufuran, a Synthesis of Tri-O-methylleprolomin and its Demethylation
Authors: Carvalho CF , Russo AV , Sargent MV
Published: September 2010

Boron trichloride has been found to be an efficient reagent for the selective cleavage of sterically hindered methoxy groups in methoxyarenes . The scope and utility of this reaction are explored with examples drawn from derivatives of benzene, naphthalene, 9,10- dihydrophenanthrene and dibenzofuran. The method is applied to the synthesis of the phytoalexins α-(56) and β- pyrufuran (58) (1,3,4- trimethoxydibenzofuran-2-ol and 1,2,4-trimethoxydibenzofuran-3-ol). A synthesis of tri-O- methylleprolomin (61), a derivative of the unusual lichen metabolite leprolomin (60), is described and its demethylation with boron trichloride is studied.
Preparation and Structure of trans-Dibromotetrakis(5,7-dihydrodibenz-[c,e]oxepin)magnesium(II)-Toluene (1/2) Solvate
Authors: Engelhardt LM , Leung W , Raston CL , White AH
Published: September 2010

The title compound, trans-[Br2Mg{O(2-CH2C6H4)2}4], prepared from MgBr2 and 5,7-dihydrodibenz-[ c,e ] oxepin , has been structurally characterized by using single-crystal X-ray methods at 295 K, being refined by least squares to a
residual of 0.058 for 2747 'observed' reflections. Crystals are monoclinic, C2/c, a 16.454(6), b 19.489(7), c 17.812(6) Ǻ, β 96.01(3)°, Z 4. The molecule lies disposed on a crystallographic twofold axis which bisects two of the ligands and passes through the magnesium. Mg-Br
are 2.623(1) Ǻ; Mg-O are 2.152(7), 2.183(7) and 2.127(4) Ǻ (× 2). Mean torsion angles about the bonds between the two phenyl rings of each ligands are 37.8, 38.0 and 39.3°.
Photoconduction in Metal-Free Phthalocyanine Films
Authors: Nespurek S , Hart RHG , Bonham JS , Lyons LE
Published: September 2010

By using pulsed photoconductivity techniques, transient action spectra have been recorded on vacuum-sublimed a metal-free phthalocyanine thin films in the wavelength range 350-700 nm. The transient photocurrents were determined at fields less than 107 V m-1 by range-limited transport of holes, the μT product of photogenerated holes being c. 2×10-14 m2 V-1. The electron μT product was about 100 times smaller. Carrier generation was a bulk phenomenon. The quantum efficiency was about 1-2% at fields up to 107 V m-1, and it was increased several fold by the presence of a layer of the acceptor pyromellitic dianhydride. Photogeneration in phthalocyanine occurred by an Onsager -type process. When pyromellitic dianhydride was present, an additional process of carrier generation, not of Onsager type, occurred, possibly associated with an exciton reaction with a charge-transfer complex between α metal-free phthalocyanine and pyromellitic dianhydride .
Arylation with Aryllead Triacetates Produced in situ by Mercury-Lead Exchange
Authors: Kozyrod RP , Pinhey JT
Published: September 2010

The addition of lead tetraacetate to diphenylmercury in chloroform leads to the rapid formation of a solution of phenyllead triacetate, which has been used directly for the C-phenylation of ethyl 2-oxocyclopentanecarboxylate (1) and 2-nitropropane in good yield. This method of arylation has been examined for a range of diorganolead compounds and the β-keto ester (1), and the results indicate that the method should be widely applicable.
Critical Points in Binary Copolymerization and the Penultimate Group Effect
Authors: Moad G , Soloman DH , Spurling TH , Vearing DJ
Published: September 2010

In order to examine the influence that a penultimate group effect can have on the number and magnitude of critical points ( azeotropic compositions) in binary copolymerization an expression for the critical point(s) has been derived. Analysis of this relationship shows that in a situation where one critical point would have been expected on the basis of terminal-model kinetics (no penultimate group effect) a modest penultimate group effect can mean that zero, one or three critical points may exist, or, in systems where no critical points would have been predicted, two critical points may exist.
Intramolecular Rearrangements of Labda-8(17),14-dien-13-ol (Manool) Derivatives
Authors: Grant PK , Hanton LR , Tsai SF
Published: September 2010

The products of epoxidation of the enol ether 8,13-epoxy-17-norlabd-8-ene (2) arise from the acid-labile acetal nature of the expected epoxide. Acid-promoted 1,2-nucleophilic rearrangements of subsequently formed epoxides give rise to the isolated products, including the novel spiro hydroxy ketone 8β,13-epoxy-7β-hydroxy-10(9→8)abeo-17-norlabdan-9-one (8), the structure of which was determined by X-ray analysis of the acetate derivative. The structure of the major product, 8,13- epoxy-17-norlabd-8-en-7-one (5), was confirmed by synthesis.
The Photochemistry of α,Β-Unsaturated Nitro Compounds and Nitronic Acids. Concerning Deconjugation and α,Β-Unsaturated Ketone Formation
Authors: Grant RD , Pinhey JT , Rizzardo E , Smith GC
Published: September 2010

The photochemistry of cyclohexylidenenitromethane (6), 3-ethyl-2-nitropent-2-ene
(7), (Z)-α-methyl-α- nitrostilbene (12), (E)-3-methyl- 1-nitro-1-phenylbut-1-ene (15) and 4,4-dimethyl-3-nitro-5α-cholest-2- ene (27) has been examined to determine the structural features required for deconjugation to the β, γ-unsaturated isomer. The mechanism of the light-induced formation of the corresponding α, β- unsaturated ketone , which may accompany deconjugation , has also been examined. Support for a scheme involving γ-hydrogen abstraction to give an unsaturated nitronic acid, followed by N- hydroxyoxaziridine formation and collapse to the ketone, is provided in the photochemistry of the stable nitronic acids, 4-t-butyl-aci-nitrocyclohexane (17) and 9-aci-nitrofluorene (18). Syntheses of the nitro olefins (6), (7), (12), (15) and (27), and the nitronic acid (17) are also reported.
Molecular Geometry of 1,2-Bis(9-anthryl)acetylene
Authors: Becker H , Skelton BW , White AH
Published: September 2010

The structure of 1,2-bis(9-anthryl)acetylene has been determined by single-crystal X-ray diffraction, being refined by least squares to a residual of 0.050 for 566 independent 'observed' reflections. Crystals are monoclinic, P21/c, a 12.432(5), b 5.112(1), c 18.758(8) Ǻ, β 126.58(2)°, Z 2. The molecule is centrosymmetric , with the two anthracene moieties coplanar. The spatial separation between H1/H8 and their centrosymmetric equivalents is 2.1 Ǻ. The length of the acetylenic bond is 1.193(10) Ǻ.
Synthesis of Analogues of GABA. XIII. An Alternative Route to (Z)-4-Aminocrotonic Acid
Authors: Allan RD , Johnston AR , Kazlauskas R
Published: September 2010

(Z)-4-Aminocrotonic acid can be conveniently prepared via crystalline phthalimido protected intermediates.
The Self-Reactions of 1-Methoxycarbonyl-1-methylethyl and Higher Ester Radicals: Combination vs Disproportionation and Oligomeric Products from Secondary Reactions
Authors: Bizilj S , Kelly DP , Serelis AK , Solomon DH , White KE
Published: September 2010

The geminate self-reactions of the title methyl, ethyl and butyl ester radicals-(2a-c), formed by decomposition of the corresponding azo precursors (1a-c) in the presence of stable nitroxide radical scavengers, were found on the basis of product analysis to comprise combination and disproportionation in the ratios 56 : 44 (methyl), 58 : 42 (ethyl) and 47 : 53 (butyl). In the absence of radical scavengers, extensive oligomerization is observed. Hydrogenation and degradation were used in conjunction with g.l.c.-m.s . to deduce the identities of the dimeric, trimeric and tetrameric products, which were in most cases subsequently confirmed by isolation and n.m.r . analysis. Of particular interest is the highly regioselective disproportionation of radical (3) to give dimethyl 4-methylpent-1-ene-2,4-dicarboxylate (8), and the further reaction of (8) with (2a) to form branched oligomers (10) and (15).
Crystal Structure of N,N,N′,N′-Tetrakis-(trimethylsilyl)ethane-1,2-diamine
Authors: Engelhardt LM , Raston CL , White AH
Published: September 2010

The title compound, [{(Me3Si)2NCH2}2], has been structurally characterized by a single-crystal X-ray structure determination at 130 K, being refined by full-matrix least-squares to a residual of 0.057 for 1244 'observed' reflections. Crystals are monoclinic, C2/c, a 21.00(2), b 9.089(8), c 11.744(9) Ǻ, β 92.31(7)°, Z 4. Molecules lie on inversion centres, but with some disorder of the methylene groups. Si -N are 1.735 Ǻ, and N-CH2 1.53(1) for the major fragment (70%). The nitrogen in the major fragment is approximately trigonal planar; Si -N- Si 124.6(3)°, Si -N-C 117.5(4), 115.5(4)°.
Diterpene Synthesis. III. Acid-Catalyzed Cyclization of Methoxyphenylethyltrimethyl-Cyclohexanols, Cyclohexenols and Cyclohexenones
Authors: Davis BR , Hinds MG , Johnson SJ
Published: September 2010

Cyclization of the methoxyphenylethyltrimethylcyclohexanols (3), (4) and (5), the cyclohexenols (6) and (7) and the cyclohexenones (20) and (21), in the presence of a variety of acids, has been studied and the products analysed by chromatographic and spectroscopic techniques. Both cis - and trans-podocarpa-8,11,13-trienes are formed, along with the rearranged compounds (16), (17) and (30). These results parallel our earlier findings and contrast with some reports in the literature.
Potential Antimalarials. V. 4-(7′-Trifluoromethylquinolin-4′-Ylamino)Phenols, 4-[2′,7′ and 2',8′-Bis(Trifluoromethyl)Quinolin-4′-Ylamino]Phenols and N4-Substituted 2,7-(and 2,8-)Bis(Trifluoromethyl)-Quinolin-4-Amines
Authors: Barlin GB , Tan WL
Published: September 2010

Mono- and di-Mannich bases of 4-(7′-trifluoromethylquinolin-4′- ylamino )phenol and its 2′,7′- and 2′,8′-bis( trifluoromethyl ) analogues, for example 2,6-bis(piperidin-1′-ylmethyl)-4-(7′-trifluoromethyl- quinolin-4′-ylamino)phenol, have been prepared. The Mannich bases from 4-(7′-trifluoromethyl-quinolin-4′-ylamino)phenol showed significant antimalarial activity when injected intraperitoneally in a single dose of 100 mg/kg to mice infected with Plasmodium vinckei vinckei ; those from its 2′,7′- and 2′,8′-bis( trifluoromethyl ) analogues did not show appreciable activity. Some N4-substituted 2,7(and 2,8)- bis ( trifluoromethyl )quinolin-4-amines with aliphatic side chains were also prepared but were inactive. The blood schizontocidal activity of mefloquine was not retained in the 2,8-bis( trifluoromethyl )-quinolin-4-amines prepared here.
The Conversion of Primary and Aryl Iodides Into the Corresponding Chlorides
Authors: Bartley JP , Carman RM , Russellmaynard JKL
Published: September 2010

Primary and aryl iodides may be converted into the corresponding chlorides through the use of phosphorus pentachloride in phosphorus oxychloride.
CNDO/2 Calculations for Organohalides
Authors: Spurling TH , Winkler DA
Published: September 2010

A CNDO/2 parameterization for performing semiempirical molecular orbital calculations for organic molecules containing bromine and iodine is presented; the results are superior to those from other parameterizations, and generally agree with ab initio calculations and experiment.
Solvent Exchange on (N,N-Diethylformamide)-[2,2',2'-Tri(Dimethylamino)Triethyl-Amine]Nickel (II)
Authors: Lincoln SF , Coates JH , Doddridge BG , Hounslow AM
Published: September 2010

A 1H n.m.r . study yields kex(298.2K) = 944�42s-1,
ΔH‡ = 23.1�0.7 kJ mol-1 and ΔS‡ = -111�2 JK-1 mol-1 for N,N- diethylformamide exchange [Ni(N(CH2CH2NMe2)3)-(OCHNEt2)]2+. These data are compared with those of related species.
Alkaline Selenide, Polyselenide Electrolytes: Concentrations, Absorption-Spectra and Formal Potentials
Authors: Lyons LE , Young TL
Published: September 2010

Spectrophotometric, titrimetric, electron spin resonance and 77Se nuclear magnetic resonance studies made on the alkaline selenide, selenium electrolyte showed that soluble selenium species existed in four oxidation states, none of the species was a radical, and the mean state of oxidation of the Se-saturated solution was equivalent to Se3.82. It was concluded that the species were Sen2- with n = 1, 2, 3 and 4, or their protonated forms. On the basis of the Nernst equation, we analysed independently (A) the titration Eredox against the mean state of oxidation of the solution and (B) the absorption spectra of solutions with different mean states of oxidation. Thus formal redox potentials E′ were determined as E′12 = -0.935, E′13 = -0.931 and E′14 = -0.914 V against s.c.e. for the couples Se2-, Se22-; Se2-, Se32-; and Se2-, Se42- respectively in 1 mol dm-3 KOH supporting electrolyte at 304 K. It followed that E′23 = -0.919 for Se32-,Se32- and E′34 = -0.778 for Se32-,Se42-. The concentration of each species at each redox potential and the absorption spectrum of each distinct oxidation state were found. Excellent fits and agreement between the two analyses were observed. Ultraviolet absorption spectra showed that the reduced ion was approximately 50% protonated in 1 mol dm-3 KOH supporting electrolyte.
Preparations and Crystal-Structures of the 2-Oxides of Some Octahydro-3,2,1-Benzoxathiazines and Octahydro-2h-3,1,2-Benzoxazaphosphorines
Authors: Goodridge RJ , Hambley TW , Ridley DD
Published: September 2010

The cis -and trans-fused 1-benzyl-1,4,4a,5,6,7,8,8a-octahydro-3,2,1- benzoxathiazine 2- oxides and cis - and trans-fused 1-benzyl-2-phenyl-1,4,4a,5,6,7,8,8a-octahydro-2H-3,1,2-benzoxazaphosphorine 2-oxides have been prepared from the cis- and trans-2-benzylaminocyclohexanemethanols and their structures have been determined by n.m.r .and crystallographic methods.
The Mechanism(S) of the Addition of Alcohols to Protonated Acetone in the Gas-Phase
Authors: Sheldon JC , Currie GJ , Bowie JH
Published: September 2010

The gas phase reactions of the systems Me2C=+OH/ROH (R = Me and Pri ) have been investigated by using a combination of experimental [ion cyclotron resonance ( i.c.r .) and flowing afterglow ( f.a .)] and ab initio (4-31G, GAUSSIAN 82) methods. A stabilized adduct, thought to correspond to Me2C=+OH...O(H)R, is observed when R = Pri but not for Me. Decomposing forms of adducts eliminate water; 18O labelling shows the major (overall) reaction to be Me2C=+OH+R18OH → Me2C=+(18O)R+H2OAb initio calculations indicate ( i ) that the product ion in this reaction is produced by two channels, both proceeding through Me2(HO)C-+O(H)R; one directly, the other indirectly through Me2C=+OH...O(H)R, and (ii) that the transition state for the key proton transfer reaction Me2(HO)C-+O(H)Me → Me2( MeO )C-+OH2 is of higher energy than reactants. The latter result suggests that precursor ion Me2C=+O
needs to be vibrationally hot for the elimination of water to occur: a comparison of i.c.r . and f.a . experiments confirms this to be the case.
The Crystal-Structures of (±)-(E)-2-(1-Amino-Ethylidene)-4,4,6-Trimethylcyclohexane-1,3-Dione [(±)-Aminoangustione] and (E)-2-(1-Aminoethylidene)-4,6,6-Trimethylcyclohex-4-Ene-1,3-Dione (Aminodehydroangustione)
Authors: Cannon JR , Patrick VA , White AH
Published: September 2010

The crystal structures of
(�)-(E)-2-(1-aminoethylidene)-4,4,6- trimethylcyclohexane-1,3-dione [(�)- aminoangustione ] (8) and (E)-2-(1- aminoethylidene )-4,6,6-trimethylcyclohex-4-ene-1,3-dione ( aminodehydroangustione ) (9) have been determined by X-ray diffraction. Diffractometer data at 295 K were refined by full-matrix least-squares to residuals of 0.057 (712 'observed' reflections) for (8) and 0.061 (571) for (9). Crystals of (8) are tetragonal I 41/a, a 21.68(1), c 9.426(6)Ǻ, Z 16; crystals of (9) are orthorhombic Pmab , a 7.077(2), b 11.421(6), c 13.283(4)Ǻ, Z 4.
Mononuclear and Binuclear Metal(II) Complexes of Ethane-1,2-Dithiolate. Preparation, Equilibrium and Redox Properties of [Ni(S2C2H4)2]2- and [Ni2(S2C2H4)3]2-, and the Structures of Ni2(S2C2H4)3]2- and [Pd(S2C2H4)2]2-
Authors: Snyder BS , Rao CP , Holm RH
Published: September 2010

The diamagnetic ethane-1,2-dithiolate complexes [Ni( edt )2]2- and [Ni2( edt )3]2- were isolated as Ph4P+ salts from reaction systems with K2( edt ) : NiCl2 mol ratios of 10 : 1 and 2 : 1, respectively. (Ph4P)2[Ni2( edt )3] crystallizes in triclinic space group Pī with a 10.409(2)Ǻ, b 12.872(4)Ǻ, c 21.235(6)Ǻ, α 76.59(2)°, β 84.65(2)°, γ 70.12(2)°, and Z 2. The anion consists of a Ni( edt ) fragment bridged to [Ni( edt )2]2- through cis sulfur atoms of different chelate rings, resulting in a complex of idealized CS symmetry. Each NiS4 coordination unit shows small deviations from planarity. Their mean S4 planes are inclined at a dihedral angle of 118.0° across the S-S vector of bridging sulfur atoms, which leads to a Ni-Ni separation of 2.914(1)Ǻ. Terminal Ni-S bond lengths average to 2.177(12)Ǻ. (Ph4P)2[Pd( edt )2].4H2O crystallizes in monoclinic space group C2/c with a 10.470(3)Ǻ, b
24.264(9)Ǻ, c 19.691(7)Ǻ, β 93.05(3)°, and Z 4. The PdS4 unit of the anion deviates from planarity by a dihedral angle of 7.7° between chelated PdS2 groups. The mean Pd-S distance is 2.318 Ǻ. In protic and aprotic solvents [Ni( edt )2]2- converts into the binuclear complex in the reaction 2[Ni( edt )2]2- → [Ni2( edt )3]2- + edt2-, which is first order in the mononuclear complex. Reactions are faster in protic solvents; in HCONMe2 at 40°C k ≈ 4×10-5 s-1. In acetonitrile [Ni2( edt )3]2- shows an irreversible oxidation at Ep,a -0.21 V v . s.c.e .; for [Ni( edt )2]2- under the same conditions Ep,a -0.61 V and E1/2 for the 2-/1- couple is estimated as -0.68 V. These values demonstrate that potentials of classical anionic NiII tetrathiolate complexes are substantially reduced relative to those of non- thiolate species (excluding dithiolenes ), and are in the region of NiII /III potentials in hydrogenases.
Synthesis of Heterobinuclear Oxo-Bridged Compounds of Chromium, Iron, Manganese and Molybdenum
Authors: Elliott RL , Nichols PJ , West BO
Published: September 2010

The synthesis of a series of heterobinuclear oxo -bridged compounds has been accomplished by redox reactions between FeII or MnII complexes of pentadentate and tetradentate salicylideneimines and thiosalicylideneimines and bidentate dithiocarbamates and either CrIVO ( tpp )( tpp ≡ dianion of 5,10,15,20-tetraphenylporphyrin) or MoVI (O)2( dtc )2 ( dtc ≡ diethyldithiocarbamato anion). The compounds are stable in solution in the absence of air but yield various homonuclear derivatives of the metals in its presence, these results indicating a degree of disproportionation of the oxo complexes. The compounds show reduced magnetic moments in line with magnetic coupling between the metal centres.
Synthesis and Characterization of Binuclear and Trinuclear Cobalt(III) Complexes With Imidazolate Bridges
Authors: Hawkins CJ , Horn E , Martin J , Palmer JAL , Snow MR
Published: September 2010

Two cobalt(III) ammine complexes are described which have an imidazolate ( Im ) ligand bridging cobalt(III) centres . Their electronic absorption spectra, 1H, 13C and 59Co n.m.r . spectra, and electrochemical data are presented. One complex is a bis [ pentaamminecobalt (III)] complex, [(H3N)5Co( Im )Co(NH3)5]5+, and the other has two pentaammineimidazolatocobalt (III) units coordinated in the cis arrangement to tetraamminecobalt (III). The crystal structure of cis - [(NH3)4Co{( Im )Co(NH3)5}2]Cl2(S2O6)2(OH).3.5H2O is reported. The crystals in the form of orange needles are monoclinic: Cc, a 20.18(1), b 17.089(9), c 15.395(7) Ǻ, β 123.76(4)°, Z 4. The structure was refined to R 0.079.
Novel Synthesis and Structure of a Bridging Peroxo Pentaaminecobalt(III) Dimer
Authors: Gainsford GJ , Jackson WG , Sargeson AM
Published: September 2010

The addition of excess glycine ethyl ester to Co{(H2NCH2CH2)3N}(OSMe2)23+ in Me2SO leads to the symmetrical dimeric peroxo ion p,p - [Co( tren )(NH2CH2CO2Et)]2O24+ under mild conditions. The single-crystal X- ray structure of the perchlorate salt is described, and the mechanism for the dimer formation is considered.
Highly Hindered Amido-Lithium and Amido-Magnesium Complexes. Crystal-Structures of [Li(Mu-N(SiMe3)2)(Tetrahydrofuran)]2 and [MgBus(Mu-N(SiMe3)2)]2
Authors: Engelhardt LM , Jolly BS , Junk PC , Raston CL , Skelton BW , White AH
Published: September 2010

Treatment of hexamethyldisilazane in thf (tetrahydrofuran) with LiBu in hexane yields [Li{μ-N(SiMe3)2}(thf)]2, (1). MgBu8Bu in heptane with hexamethyldisilazane results in initially formation of [MgBus(μ- N(SiMe3)2}]2, (2), then ?Mg{N(SiMe3)2}2,(3). The structures of (1) and (2) have been determined by X-ray diffraction. Remarkably, they are isomorphous: crystals are tetragonal, space group P4n2 with a 9.970(7), c 16.753(9) Ǻ for (1), and a 9.524(6), c 17.385(9) Ǻ for (2), with Z = 2. The lattices are comprised of discrete molecules with symmetry 222, and thus Bus disorder in (2), yith the amido ligands bridging three- coordinate metal centres [Li-N 2.025(9), Li-O 1.882(14) Ǻ,
Li-N-Li 73.7(5)°, N-Li-N 106.3(6)°, O-Li-N 126.8(3)° (1); Mg-N 2.118(4), Mg-C 2.08(1) Ǻ, Mg-N-Mg 87.1(2)°, N-Mg-N 92.9(2)°; C-Mg-N 133.6(1)°(2)].
Kinetic Simulation of Polymerization Involving Termination by Reversible Chain Transfer
Authors: Johnson CHJ , Moad G , Solomon DH , Spurling TH
Published: September 2010

Numerical integration has been used as a means of simulating the title polymerization so that the variation of molecular weight and molecular weight distribution with reaction time (conversion) can be evaluated. The time/conversion dependence of the polydispersity (R) has been evaluated as a function of the relative magnitude of the rate constants associated with the initiation/termination equilibria . It is shown that the short term behaviour of R and the rate of approach to the value (R = 4/3) predicted by the steady state treatment have a marked dependence on the choice of rate constants.
Oxidation of 1-Naphthols by Lead Tetraacetate in Acetic Acid
Authors: Greenland H , Pinhey JT , Sternhell S
Published: September 2010

A detailed study of the lead tetraacetate-acetic acid oxidation of 1-naphthol , 4-acetoxy-1-naphthol, 2-methyl-1-naphthol, 2,3-dimethyl-1- naphthol and 1,2,3,4-tetrahydro-9-anthrol (17) has been carried out. In the case of 1-naphthol the major product was 4-acetoxy-1-naphthol (4), with 2,2-diacetoxynaphthalen-1(2H)-one (2) being the only other product formed in significant yield. Attack at C4 was again the main reaction with 4-acetoxy-1-naphthol, which gave 1,4-naphthoquinone as the major product. Acetoxylation occurred predominantly at C2 with 2-methyl-1-naphthol and 2,3-dimethyl-1-naphthol to give the naphthalen-1(2H)-ones (11) and (12) respectively. In both cases minor amounts of 4- acetoxylated derivatives and quinones were also produced. 1,2,3,4- Tetrahydro-9-anthrol (17) gave an analogous set of products, the yields of which showed an unusual concentration dependence. In dilute solution 10-acetoxy-1,2,3,4-tetrahydro-9-anthrol(19) was produced in high yield, whereas with a high substrate concentration a good yield of 9a-acetoxy- 1,2,3,4-tetrahydroanthracen-9(9aH)-one (18) was obtained.
The Chlorination of 2-Tert-Butyl-4,6-Dimethylphenol and 2,6-Di-Tert-Butyl-4-Methylphenol. The Formation of 5,6-Dichloro-4-Methylenecyclohex-2-Enones
Authors: Hartshorn MP , Judd MC , Robinson WT
Published: September 2010

The chlorination in acetic acid of 2-t-butyl-4,6-dimethylphenol (1) gives two chloromethylene compounds (4) and (5), and trichloro ketones (6) and (7). In contrast, 2,6-di-t-butyl-4-methylphenol (2) gives six chlorination products (14)-(19). The notable feature of the reactions is the modification of the 4-methyl groups of the phenols (1) and (2). The modes of formation of all reaction products are described. X-ray structure determinations are reported for compounds (5),(6),(15),(17), (19) and
(21).
DNA-Binding Compounds. II. Synthesis of a Peptide-Linked Triacridine
Authors: Mack POL , Kelly DP , Martin RF , Wakelin LPG
Published: September 2010

A novel peptide-linked triacridine (2) of the type‡ ( Acr )-A-c( Acr )-B-( Acr ) has been synthesized
in which the central trifunctional group (-c<) is 2,4-diaminobutyric acid (A2bu), spacer A is - γAbu-Tyr-Lys-Lys-Gly - and spacer B is - Gly-Gly-Gly-Gly-NH (CH2)3NH-. This DNA-binding ligand was prepared by solution phase methodology in 12 steps from known compounds.
The Association Properties of Iodide With Cetyltrimethylammonium Bromide Micelles as Revealed by Steady-State Fluorescence Quenching Measurements
Authors: Blatt E
Published: September 2010

The association behaviour of I- with cetyltrimethylammonium bromide micelles was investigated by the fluorescence quenching technique with 2-(9-anthroy1oxy) palmitic acid and 12-(9- anthroyloxy) stearic acid as probes. A 1 : 1 ground-state complex occurs between I- and 12-(9-anthroyloxy) stearic acid with an equilibrium constant, Kc , of 408 dm3 mol-l. In both cases I- partitions into the micelle with a partition coefficient, Kp , of about 365. The results show the importance of probe solubilization site and probe/quencher interaction in the elucidation of micelle structure and permeability.
Studies in the Cycloproparene Series: Competitive Pathways in the Dehydrohalogenation Route to 2-Halobicyclo[4.1.0]Hepta-1,3,5-Trienes
Authors: Halton B , Randall CJ , Gainsford GJ , Robinson WT
Published: September 2010

The (1α,2β,3α,6α)-2,3,7,7-tetrahalobicyclo[4.1.0]heptanes (8a-c), whose structures have been determined by X-ray methods, give 2-halobicyclo[4.1.0]hepta-1,3,5-trienes (5) upon dehydrohalogenation. The 'mixed' halide (8c) and partly labelled [7-13c]-(8b,c) have revealed the presence of competing pathways in these conversions. By comparison, dehydrohalogenations of the (1α,3α,4β,6α)-3,4,7,7-tetrahalobicyclo[4.1.0]heptanes (3) give unrearranged 3-halobicyclo[4.1.0]-hepta-1,3,5-trienes (4).
Dipole Moments, Kerr Constants and Solute Conformations of the Aryl Methyl Sulfones p-XC6H4S(02)CH3 (X = H, Cl, BR or NO2)
Authors: Aroney MJ , LeFevre RJW , Pierens RK , Stootman HJ , Yong MGM
Published: September 2010

Measurements are reported of the infinite-dilution dipole moments and molar Kerr constants of dimethyl sulfone and of the four aryl methyl sulfones p-XC6H4S(02)CH3 (X = H, Cl, Br or NO2) dissolved in carbon tetrachloride or dioxan at 298 K and under light of 589 nm. The experimental data are analysed to obtain information on the solution-state conformations in relation to steric and electromeric effects operative between the aryl and methanesulfonyl groups.
On the Origin of the Red Color of Aqueous-Solutions of 2,3-Dichloro-5,6-Dicyano-1,4-Benzoquinone (ddq). Crystal Structure of the Ammonium Salt of 2-Cyano-5,6-Dichloro-3-Hydroxy-1,4-Benzoquinone
Authors: Becker HD , Skelton BW , White AH
Published: September 2010

Hydrolysis of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone in aqueous ethanol gives the deep-red coloured ammonium salt of a monocyano-dichloro-monohydroxy-benzoquinone which crystallizes in the tetragonal space group I41 /a, a 20.832(5), c 8.618(2) �, Z 16. Single-crystal X-ray structure determination (R 0.036 for 1185 'observed' reflections) show the presence of ammonium cations forming hydrogen bonds in the lattice alternatingly with the tautomeric anion of 2-cyano-5,6-dichloro-3-hydroxy-1,4-benzoquinone and 3-cyano-5,6-dichloro-4-hydroxy-1,2-benzoquinone.
Photoelectrochemical Cells With Single-Crystal Cadmium Telluride and Alkaline Telluride, Ditelluride Redox Couple
Authors: Lyons LE , Morris GC , Raftery NA , Young TL
Published: September 2010

In the photoelectrochemical cell Ga -In /n- CdTe (single crystal) 0.1 M Te2- , Te22-, OH- /Pt the efficiency of energy conversion of solar radiation (AM2 spectral distribution, 58 mW cm-2 was increased from the previously reported 5% to 9.0%, by etching the polished crystal surface, by making [Te2-] as large as practicable by using KOH as the supporting electrolyte, and by optimizing [Te22- At reduced irradiances the energy conversion efficiency was higher. At AM2, an efficiency of 14% is predicted to be attainable. Etching with chromic acid (Na2Cr2O7 in 3M HNO3) increased the open-circuit voltage in 0.1 M partly oxidized Na2Te, 5 M KOH, to 0.74 V from 0.48 V as observed on the polished but unetched crystal, and increased the short-circuit photocurrent density Jsc from 4 mA cm-2 to 13 mA cm-2 (AM2 spectral distribution, 58 mW cm-2. Etching reduced the surface defect concentration as recorded by two-beam photocurrent spectroscopy. For redox potentials Eredox more negative than - 1.12 V v . s.c.e . the crystal potential at open circuit Ec,oc was independent of the value of Eradox which was varied by changing [Te22-]; a change in Eredox therefore produced a quantitatively similar change in the open-circuit photovoltage Uoc (both at 1 mWcm-2 of 633 nm radiation and at AM2 solar radiation) and so Fermi-level pinning did not occur. Uoc was proportional to In Jsc . The very negative value of - 1.86 V v . s.c.e . observed for Ec,oc was attributed to adsorbed anionic charge, estimated as c.1013 elementary charges cm-2, which gave rise to a potential drop of 1.5 V across the Helmholtz layer.
The Crystal and Molecular-Structure of Two Complexes of Cobalt(III) With Pentaaza Macrocyclic Ligands Chloro (1,4,7,10,14-pentaazacycloheptadecane)cobalt(III) Bromide Chloride Hydrate [Co(C12H29N5)Cl] (Br0.33Cl1.67)H2O and Bromo(1,4,7,11,15-pentaazacyclooctadecane)cobalt(III) Bromide [Co(C13H31N5)Br]Br2
Authors: Curtis NF , Gainsford GJ , Osvath P , Weatherburn DC
Published: September 2010

The structures of the compounds chloro (1,4,7,10,14-pentaazacycloheptadecane) cobalt(III) bromide chloride hydrate, [Co( chad )Cl] ( Br0.33Cl1.67)H2O(1) and bromo (1,4,7,11,15-pentaazacyclooctadecane) cobalt(III) bromide, [Co( coad )Br]Br2(2),have been determined by X-ray diffractometry. [Compound (1) orthorhombic, space group P bac, a 1208.5, b 2305.5, c 1318.9 pm, Z 8, R 0.056, Rw 0.071 for 1943 reflections. Compound (2), triclinic, space group P1, a 930.8, b 953.5, c 1120.3pm, α 84.60,β 398.82, γ 105.26�, Z 2, R 0.045, RW0.054 for 4821 reflections.] The compounds have structures with two ( chad ) or three ( coad ) six-membered chelate rings in the equatorial (N4) plane, but with different configurations of the chiral nitrogen centres ; chad : 1SR , 4SR, 7RS, 10RS, that is, with only the NH group at the junction of the two six-membered chelate rings on the same side of the N4 plane as the axial nitrogen; coad : 1 RS, 7SR, 11 SR, 15RS, that is, with NH groups of the central six-membered chelate ring on the same side of the N4 plane as the axial nitrogen, and the others on the opposite side. The chad compound has regular octahedral geometry, with one chair and one boat conformation six-membered chelate ring. The coad compound has distorted octahedral geometry, with long Co-N distances in the N4 plane, attributed to intra-ligand interactions.
Fluorescence Probe Studies of Anthracene and 9-Methylanthracene in Detergent Micelles
Authors: Blatt E
Published: September 2010

The photophysical properties of anthracene and 9-methylanthracene have been investigated in a variety of solvents and the resulting information used to interpret data after incorporation of the two fluorophores into aqueous solutions comprising Triton X-100, cetyltrimethylammonium bromide (ctab) or sodium dodecyl sulfate (sds) micelles. The fluorescence probe methods used to elucidate micellar properties such as microviscosity , micropolarity, and the permeability of the micelle/water interface to aromatic molecules and ions, included steady-state polarization, time-resolved anisotropy and steady-state and lifetime quenching techniques. NN- Dimethylaniline (dma) and I-ions were shown to partition into Triton X-100 micelles with partition coefficients, Kp, of about 70 and 51, respectively. Excimer formation between dma and the two probes was not observed in Triton X-100 micelles, these results
indicating high micropolarities (E ≈30) and microviscosities ; from polarization and anisotropy measurements the microviscosity was in the range 60-156 cP . In contrast, excited-state complexation was observed in ctab and sds. For anthracene in ctab, triplex formation occurred with an equilibrium constant, Kc, of 137 dm3 mol-l. Weak ground-state complexation between I- and the two probes was also observed in Triton X-100 and ctab micelles with equilibrium constants, Kc, in the range 0.36-9.6 dm3 mol-l. The importance of probe characterization is highlighted by the results in sds where multiple-site occupancy occurred.
3-Amino-5-Hydroxybenzoic Acid in Antibiotic Biosynthesis. IX. The Status of Reduced Derivatives in Mitomycin Biosynthesis
Authors: Rickards RW , Rukachaisirikul V
Published: September 2010

The addition of (methylene-2H2)-3-amino-5-hydroxybenzyl alcohol (8) hydrochloride to growing cultures of Streptomyces verticillatus inhibits production of the mitomycin antibiotic porfiromycin (2) by the microorganism. No incorporation of deuterium into porfiromycin occurs, and the isotopic composition of the alcohol recovered from the fermentation is unchanged. The significance of these results with regard to the immediate metabolic precursors of 3-amino-5-hydroxybenzoic acid (3) and the reduction stages involved in the established conversion of this amino acid into mitomycins are discussed.
Diterpene Synthesis. IV. Synthesis of Some Octahydrophenanthrenes and a Contribution to the Mechanisms of Cyclialkylations
Authors: Davis BR , Johnson SJ , Woodgate PD
Published: September 2010

The cis octahydrophenanthrene (3), a product of the acid-catalysed cyclialkylation of alcohol (1), has been synthesized. Various analogues having cis A/B stereochemistry have also been isolated from cyclization reactions; in these cases there is no rearrangement of the carbon skeleton, as shown by isotopic labelling. Variable temperature n.m.r. studies have been used to define the conformations of some of the cis octahydrophenanthrenes. The mechanisms of cyclialkylations leading to octahydrophenanthrenes can now be clarified.
A Convenient Synthesis of 5-Alkylbicyclo[3.1.0]hexan-2-ones Including the Natural Product Sabina Ketone
Authors: Hamon DPG , Shirley NJ
Published: September 2010

Simple 5-alkylbicyclo[3.1.0]hexan-2-ones, including the natural product sabina ketone, can be prepared in four steps from aromatic ethers via Birch reduction, hydrogen chloride addition, hydrolysis and then base treatment of the resultant 4-chlorocyclohexanones.