Journal of Physical Organic Chemistry

Cover image for Vol. 24 Issue 10

Special Issue: ISRIUM at Pacifichem 2010

October 2011

Volume 24, Issue 10

Pages 865–1017

Issue edited by: D. Merrer, M. Platz

  1. Preface

    1. Top of page
    2. Preface
    3. Review
    4. Mini Review
    5. Short Communications
    6. Research Articles
    1. ISRIUM at Pacifichem 2010–Reactive Intermediates (page 865)

      Dina C. Merrer and Matthew S. Platz

      Article first published online: 27 SEP 2011 | DOI: 10.1002/poc.1924

  2. Review

    1. Top of page
    2. Preface
    3. Review
    4. Mini Review
    5. Short Communications
    6. Research Articles
    1. Solvation and complexation of carbenes – a perspective (pages 866–875)

      Robert A. Moss

      Article first published online: 24 JUN 2011 | DOI: 10.1002/poc.1869

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      Complexes of several carbenes with aryl ethers are documented by laser flash photolysis with UV-visible spectroscopic detection. The carbenes include methylchlorocarbene, benzylchlorocarbene, phenylchlorocarbene, p-nitrophenylchlorocarbene, and dichlorocarbene, while the complexing ligands are anisole, various methylanisoles, dibenzo-18-crown-6, dibenzofuran, 1,3-dimethoxybenzene, and 1,3,5-trimethoxybenzene.

  3. Mini Review

    1. Top of page
    2. Preface
    3. Review
    4. Mini Review
    5. Short Communications
    6. Research Articles
    1. Experimental consideration of covalent-bonding interactions in stacks of singlet biradicals having Kekulé structures (pages 876–882)

      Akihiro Shimizu, Masayoshi Nakano, Yasukazu Hirao and Takashi Kubo

      Article first published online: 1 JUN 2011 | DOI: 10.1002/poc.1873

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      Kekulé singlet biradicals stabilized by phenalenyl rings afford one-dimensional stacks in the solid state, in which covalent bonding interactions exist not only within a molecule but also between molecules. Through the covalent bonding interactions spreading over the stack, the lowest-energy absorption band shifts to a lower-energy region in the solid state relative to the solution band, and an electro-conductive property in a single component state is also observed.

  4. Short Communications

    1. Top of page
    2. Preface
    3. Review
    4. Mini Review
    5. Short Communications
    6. Research Articles
    1. Ring strain release as a strategy to enable the singlet state photodecarbonylation of crystalline 1,4-cyclobutanediones (pages 883–888)

      Gregory Kuzmanich and Miguel A. Garcia-Garibay

      Article first published online: 21 JUL 2011 | DOI: 10.1002/poc.1902

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      It has beenshown that efficient decarbonylation in crystals requires triplet state reactivity and radical stabilizing groups on the α-carbons to slow down thereturn of the acyl-alkyl biradical back to the starting material. Using the release of ring strain for a similar purpose, we report four examples of aliphatic, cyclobutanediones that undergo efficient double singlet state decarbonylation in the crystalline state.

    2. Effects of CF3 groups and charged substituents on singlet carbene stabilities–a density functional theory study (pages 889–893)

      Myoung-Geun Song and Robert S. Sheridan

      Article first published online: 9 AUG 2011 | DOI: 10.1002/poc.1913

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      Density functional theory calculations exploring the effects of CF3 groups and cationic substituents on singlet carbene stabilities are described.

  5. Research Articles

    1. Top of page
    2. Preface
    3. Review
    4. Mini Review
    5. Short Communications
    6. Research Articles
    1. Stereochemical deuterium-labeling study on the denitrogenation of 7,7-diethoxy-2,3-diazabicyclo[2.2.1]hept-2-ene (pages 894–901)

      Shingo Yagi, Yoshikazu Hiraga, Ryukichi Takagi and Manabu Abe

      Article first published online: 12 JUN 2011 | DOI: 10.1002/poc.1872

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      Deuterium-labeling study clarifies the stereoselectivity of the denitrogenation of 7,7-diethoxy-2,3-diazabicyclo[2.2.1]hept-2-ene.

    2. Phenylethanol derivatives as triplet sensitizers for 1-azidoadamantane (pages 902–908)

      Ranaweera R. A. Upul Ranaweera, Sridhar Rajam and Anna D. Gudmundsdottir

      Article first published online: 22 AUG 2011 | DOI: 10.1002/poc.1922

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      The triplet excited state of phenylethanol derivatives was characterized with laser flash photolysis, phosphorescence and density functional calculations. The phenylethanol derivatives were used as sensitizers for azidoadamantaneto form triplet adamantanenitrene.

    3. Generation and reactivities of triplet diphenylcarbenes protected by bulky groups as para substituents (pages 909–920)

      Katsuyuki Hirai, Keiji Hatanaka, Tsuyoshi Yamaguchi, Akiko Miyajima, Toshikazu Kitagawa and Hideo Tomioka

      Article first published online: 18 JUL 2011 | DOI: 10.1002/poc.1898

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      Triplet diphenylcarbenes 31 having kinetic protectors as the para substituents were generated by photolysis of the precursor diphenyldiazomethanes 1-N2 and were shown to be long-lived carbenes with a half-life of 2.2-10 s in solution at room temperature.

    4. Density functional theory study of silole-fused tetramethyleneethane biradicals with orbital interactions (pages 921–928)

      Yusuke Kano, Kazuhiko Mizuno and Hiroshi Ikeda

      Article first published online: 22 JUL 2011 | DOI: 10.1002/poc.1891

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      Density functional theory and time-dependent density functional theory calculations of the silole-fused TME (3,4-dimethylenesilole) biradical (7) were carried out. The wavelength of the electronic transitions of 37 (λET = 450 nm) was shown to be different from that of 17 (λET = 673 nm). The difference is attributed to orbital interactions between the two allyl radical moieties, especially, the existence of double σ*–π* conjugation, that is, π*–σ*–π* conjugation, in the silole subunit.

    5. Reactivity of carbene•phosphine dimers: proton affinity revisited (pages 929–936)

      Min Liu, Mu Chen, Sisi Zhang, Ill Yang, Brian Buckley and Jeehiun K. Lee

      Article first published online: 18 JUL 2011 | DOI: 10.1002/poc.1890

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      Gas phase studies of N-heterocyclic carbenes reveal unexpected reactivity and surprising proton affinities.

    6. Kinetics and mechanisms of the reactions of transient silylenes with amines (pages 937–946)

      Svetlana S. Kostina, Tishaan Singh and William J. Leigh

      Article first published online: 31 JUL 2011 | DOI: 10.1002/poc.1908

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      The complexation and N–H insertion reactions of SiMe2, SiPh2, and SiMes2 with amines have been characterized by fast kinetics methods, in conjunction with computational studies. The role of catalysis in the N–H insertion process is evaluated.

    7. Dynamic control of dichlorocarbene addition to cyclopropene (pages 947–951)

      Dina C. Merrer and Charles Doubleday

      Article first published online: 7 JUL 2011 | DOI: 10.1002/poc.1883

      Thumbnail image of graphical abstract

      Dichlorocarbene addition to cyclopropene has been studied with direct dynamics trajectories. The trajectories yielded bicyclobutane and butadiene products in a 4.7:1 ratio, consistent with experimental 4:1 ratio, thereby supporting that this reaction is under dynamic control.

    8. Heteroatom functionalization of phenalenyl: synthesis, structures, and properties of hexa-substituted phenalenyliums (pages 952–959)

      Akira Ueda, Kenta Yoshida, Shuichi Suzuki, Kozo Fukui, Kazuhiro Nakasuji and Yasushi Morita

      Article first published online: 22 AUG 2011 | DOI: 10.1002/poc.1916

      Thumbnail image of graphical abstract

      Two kinds of heteroatom-functionalized phenalenyl derivatives, 1,4,7-trimethoxy-3,6,9-tris(n-propylamino)phenalenylium 1+ and 3,4,6,7-tetramethoxy-1,9-dithiophenalenylium 2+, have been synthesized and isolated as air-stable tetraphenylborate salts (see Figure). The structural and electronic features were experimentally investigated by X-ray crystal structure analysis, cyclic voltammetry, and UV-vis and fluorescence measurements with the help of DFT calculations. Furthermore, the heteroatom effects attributable to the electron-donating alkoxy, amino, or thio groups introduced at all of the α-carbons in the phenalenylium skeleton were evaluated in detail.

    9. Reactions of a putative metabolite of the model antitumor drug 2-(4-aminophenyl)benzothiazole with purines and pyrimidines (pages 960–968)

      Michael Novak and Mrinal Chakraborty

      Article first published online: 25 JUL 2011 | DOI: 10.1002/poc.1905

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      Kinetics of the formation and the structures of purine and pyrimidine adducts of a nitrenium ion derived from a putative metabolite of a model antitumor drug, 2-(4-aminophenyl)-benzothiazole, have been studied and compared with those obtained from the nitrenium ion of the carcinogen, 4-aminobiphenyl.

    10. Wolff rearrangement of β-alkynyl-α-diazo-β-ketoesters: light-induced acetylene–allene isomerization and its use for activation of enediynes (pages 969–975)

      Natalia G. Zhegalova and Vladimir V. Popik

      Article first published online: 21 JUN 2011 | DOI: 10.1002/poc.1875

      Thumbnail image of graphical abstract

      Photo-Wolff reaction of β-phenylethynyl-a-diazo-β-ketoester is regioselective and produces in alcohols a-phenylethynyl-β-diester, which undergoes rapid ( < 1 min) tautomerization to 1,1- dicarbalkoxyallene. Introduction of o-(3-hydroxy-1-propynyl) fragment in the structure of the parent a-diazo-β-ketoester allowed us to achieve two goals simultaneously: ring closure by intramolecular nucleophilic attack of propargyl alcohol on photo-generated ketene, and the subsequent acetylene 舑 allene rearrangement. The resulting enyne-allene undergoes spontaneous Myers-Saito cycloaromatization generating 1,4-biradical. In alcohol solutions, however, ketene reaction with solvent outcompetes the intramolecular process.

    11. EPR spectroscopic and computational characterization of the 2-dehydro-m-xylylene and 4-dehydro-m-xylylene triradicals (pages 976–992)

      Patrik Neuhaus, Michael Winkler and Wolfram Sander

      Article first published online: 16 AUG 2011 | DOI: 10.1002/poc.1911

      Thumbnail image of graphical abstract

      The 2-DMX and 4-DMX triradicals were isolated in cryogenic argon matrices and characterized by EPR spectroscopy. The electronic structures, excited states, and magnetic properties of all three isomers are discussed on the basis of quantum chemical computations.

    12. Detection of nitroxyl (HNO) by a prefluorescent probe (pages 993–998)

      Meredith R. Cline and John P. Toscano

      Article first published online: 12 JUN 2011 | DOI: 10.1002/poc.1871

      Thumbnail image of graphical abstract

      The prefluorescent probe 4-((9-acridinecarbonyl)amino)-2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO-9-AC) has been used to detect HNO in aqueous solution and to differentiate it from nitric oxide (NO). The utility of TEMPO-9-AC as a probe for HNO has been shown using the common HNO donors Angeli's salt and Piloty's acid along with a recently reported HNO donor, 2-bromo-Piloty's acid.

    13. 4-Quinolylnitrene and 2-quinoxalinylcarbene (pages 999–1008)

      Chris Addicott, Holger Lüerssen, Martin Kuzaj, David Kvaskoff and Curt Wentrup

      Article first published online: 27 JUL 2011 | DOI: 10.1002/poc.1904

      Thumbnail image of graphical abstract

      4-Quinolylnitrene 21 and 2-quinoxalinylcarbene 17 undergo ring expansion to the cyclic ketenimine 19 as well as ring opening to a nitrile ylide 25 and a ketenimine 26 in matrix photochemistry experiments. A second nitrene assigned as 24 is observed by ESR spectroscopy. Solution photolysis of 22 in the presence of dialkylamines leads to trapping of the azirene 23 to afford 5-dialkylaminobenzo[e]-1,4-diazepines 35.

    14. Generation of triplet carbenes by oxidation of an allene compound (pages 1009–1017)

      Shin-ichi Fuku-en, Torahiko Yamaguchi, Satoshi Kojima and Yohsuke Yamamoto

      Article first published online: 12 JUN 2011 | DOI: 10.1002/poc.1870

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      Experimental and computational methods indicate that the double oxidation of heterocyclic allene compounds is viable as a new approach for generating triplet carbenes.

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