bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fluorenylindate: Verbindungen mit schwachen In — C‐Bindungen
Authors: Neumüller Bernhard 
Published: July 2007

Fluorenylindates: Compounds with Weak In — C BondsIn diethyl ether, fluorenyllithium reacts with indium(III) chloride to yield a lithium tetrafluorenylindate (1). Recrystallisation from THF gives [Li(THF)4][In(C13H9)4] (2). If the reaction is carried out in THF, the chlorotrifluorenylindate [Li(THF)4]‐[ClIn(C13H9)3] (3) is isolated. According to crystal structure analyses 2 has long and weak In — C bonds [224.8(5) – 230.3(5) pm], while these distances in 3 are somewhat shorter [222.9 (5) – 226.7(4) pm].
Übergangsmetall‐Silyl‐Komplexe, 44. Darstellung der zweikernigen Silyl‐Komplexe (CO)3(R3Si)Fe(μ‐PR′R′′)Pt(PPh3)2 durch oxidative Addition von (CO)3(R′R′′HP)Fe(H)SiR3 an (C2H4)Pt(PPh3)2
Authors: Reinhard Georg , Knorr Michael , Braunstein Pierre , Schubert Ulrich , Khan Saeed , Strouse Charles E. , Kaesz Herbert D. , Zinn Alfred 
Published: July 2007

Transition Metal Silyl Complexes, 44. — Preparation of the Binuclear Silyl Complexes (CO)3(R3Si)Fe(μ‐PR′R′′)Pt(PPh3)2 by Oxidative Addition of (CO)3(R′R′′HP)Fe(H)SiR3 to (C2H4)Pt(PPh3)2The complexes (CO)3(R′R′′HP)Fe(H)SiR3 (1) [PHR′R′′ = PHPh2, PH2Ph, PH2Cy; SiR3 = SiPh3, SiPh2Me, SiPhMe2, Si(OMe)3] react with Pt(C2H4)(PPh3)2 to give the dinuclear, silyl‐substituted complexes (CO)3(R3Si)Fe(μ‐PR′R′′)Pt(PPh3)2 (2) in high yields. Upon reaction of 2 (R = R′ R′′ = Ph) with CO, the PPh3 ligand at Pt being trans to the PPh2 bridge is exchanged, and (CO)3(Ph3Si)Fe(μ‐PPh2)Pt(PPh3)CO (3) is formed. Complex 3 is characterized by an X‐ray structure analysis. The rather short Fe — Si distance [233.9(2) pm] and the infrared spectrum of 3 indicate that the Fe — Pt bond is quite polar.
Mehrfachbindungen zwischen Hauptgruppenelementen und Übergangsmetallen, CIX. Strukturchemische Aspekte der Fluorolefin‐;Chemie von Osmiumtetraoxid: Halogenierte Osmatester und Folgeprodukte
Authors: Herrmann Wolfgang A. , Eder Stefan J. , Scherer Wolfgang 
Published: July 2007

Multiple Bonds Between Main Group Elements and Transition Metals, CIX. — Structural Aspects of Fluoroolefin Oxidation by Osmium Tetraoxide: Halogenated Osmate Esters and Their ProductsThe crystal and molecular structures of the first fluorinated osmate ester 1, the dioxoosmium(VI) dichloride 2, and the dioxoosmium(VI) oxalate 3 have been determined by single‐crystal X‐ray diffraction. They all contain the trans‐osmyl group {OsO2}2+ and cis‐oriented sets of ligands, typical of complexes (py)2OsO2X2 (py = pyridine). Increasing electron‐withdrawing power of the ligands X entails shortening of the OsN bonds, resulting in higher stability of these complexes against dissociation of pyridine.
Organomolybdän‐ und Organowolfram‐;Reagenzien, III. Chemoselektive, nichtbasische Carbonylmethylenierungs‐;Reagenzien aus MoOCl3(THF)2 und MoOCl4: Bildung, Thermolabilität, Struktur
Authors: Kauffmann Thomas , Fiegenbaum Petra , Papenberg Michael , Wieschollek Raphael , Wingbermühle Dorothea 
Published: July 2007

Organomolybdenum and Organotungsten Reagents, III. — Selective, Nonbasic Carbonylmethylenation Reagents from MoOCl3(THF)2 and MoOCl4: Formation, Thermolability, StructureFrom the family of more than 20 carbonylolefinating μ‐methylene molybdenum and tungsten complexes[1,2] the reagent “3”, obtained in solution by treatment of MoOCl3(THF)2 with two equivalents of methyllithium, is probably the most favorable one for chemoselective carbonylolefination reactions. As judged by the 13C‐ and 1H‐NMR spectra the reagent is not a single species, but a mixture of either isomeric 1,3‐dioxo‐1,3‐dimolybda(V)cyclobutane complexes 3, differing in the position of the ligands Cl, O, and THF at the molybdenum atoms, or of oligomers of 3. — Treatment of MoOCl4 with two equivalents of methyllithium gave a carbonylolefinating reagent “4” which, according to NMR data, consists of isomeric or oligomeric 1,3‐dioxo‐1,3‐dimolybda(VI)cyclobutane complexes 4. Both reagents are labile at room temperature, but differ from the classical carbonylolefinating reagents by an acidic rather than a basic character, resistance to hydroxy groups, and high selectivity.
Organomolybdän‐ und Organowolfram‐;Reagenzien, IV. über die Chemoselektivität des carbonylmethylenierenden Reagenzes aus 2 MoOCl3(THF)2 und 4 CH3Li
Authors: Kauffmann Thomas , Baune JüRgen , Fiegenbaum Petra , Hansmersmann Ursula , Neiteler Christel , Papenberg Michael , Wieschollek Raphael 
Published: July 2007

Organomolybdenum and Organotungsten Reagents, IV. — About the Chemoselectivity of the Carbonylmethylenating Reagent from 2 MoOCl3(THF)2 and 4 CH3LiFrom a series of carbonylolefinating Mo complexes the reagent “3”, obtained by low‐temperature methylation of two equivalents of MoOCl3(THF)2 with four equivalents of methyllithium and warming up, is especially favourable for chemoselective carbonylolefination reactions. It is readily accessible, reacts at low temperatures, exhibits high aldehydeversus‐ketone selectivity (Tables 1, 2; Scheme 2), high cheleselectivity (preference of a keto group in the α‐ or β‐ position to a hydroxy group before an isolated keto group: Table 4; Scheme 3), and in some cases anticheleselectivity (Table 6). It is nonbasic and tolerates hydroxy groups (even water in the solvent) as well as acyl chloride groups (Table 8). — The chemoselectivity of 3 is compared in several cases with other carbonylolefinating reagents.
„Dimerisierungsprodukte”︁ von 1,2‐Cyclooctadien?
Authors: Pietruszka JüRg , Künig Wilfried A. , Maelger Harald , Kopf JüRgen 
Published: July 2007

“Dimerization Products” of 1,2‐Cyclooctadiene?The conversion of 8,8‐dibromobicyclo[5.1.0]octane (2) with methyllithium is known to yield kinetically labile 1,2‐cyclooctadiene (1). This strained cyclic allene readily dimerizes at ambient temperature. The 1‐methyl derivative enjoys greater kinetic stability, but nevertheless only three [2 + 2]‐cycloaddition products can be isolated after workup. Whereas the dimerization products 17, 22, 23, 24 can be predicted from recent studies, the carbene adducts 15 and 16 were not yet reported. The stereochemistry of 17 and 22 is determined by X‐ray structure analysis of their Diels‐;Alder adducts with tetracyanoethylene.
Cyclophanes, XXXVIII. [2]Metacyclo[2]indenophanes: Synthesis, Anions and Iron Complexes
Authors: Bodwell Graham J. , Frim Ron , Hopf Henning , Rabinovitz Mordecai 
Published: July 2007

Abstract[2.2]Metacyclophane can be directly formylated according to the Rieche method to give 4‐formyl[2.2]metacyclophane (12) in 44% yield. The synthesis of the [2]metacyclo[2]indenophane 8 from the aldehyde 12 by the pathway previously employed for the corresponding [2.2]paracyclophanes failed due to the harsh conditions of the cyclization step. An alternative synthesis of 8 and its isomer 9 involving the construction of the five‐membered ring prior to that of the cyclophane unit succeeded. Compounds 8 and 9 were obtained as an 82:18 mixture, deprotonation of which afforded the anion 10, which shows long‐term stability. The 1H‐NMR spectrum of this anion does not exhibit a through‐space charge transfer due to its structure. The 1H‐NMR parameters and molecular mechanics calculations are discussed. Both faces of 10 react in the presence of FeCl2 · 2 THF and a twentyfold excess of LiCp to give a 70:30 mixture of the ferrocene derivatives 7 and 35.
Trimethylsilylcyanid als Umpolungsreagens, XXII. Nucleophile Acylierung α,β‐ungesättigter Aldehyde durch umgepolte α,β‐ungesättigte Aldehyde
Authors: Hünig Siegfried , Schäfer Matthias , Schweeberg Walter 
Published: July 2007

Trimethylsilyl Cyanide — A Reagent for Umpolung, XXII. — Nucleophilic Acylation of α,β‐Unsaturated Aldehydes by Umpolung of α,β‐Unsaturated AldehydesAmbident anions 1aA → 1dA, obtained from 1a — d by LDA, are treated with α,β‐unsaturated aldehydes 2a — c. In all cases the kinetically controlled 1,2/α adducts 3 are formed which in contrast to 1,2/α adducts with α,β‐unsaturated ketones do not rearrange to the thermodynamically stable 1,4/α‐ or 1,4/γ products 4a and 6. Adducts 4 are smoothly formed if imines of 2 are applied. A thermal oxy‐Cope rearrangement transforms adducts 3 into 6. Substantial proportions of 1,2/γ adducts 5 are produced from 1A and 2 in the presence of magnesium bromide.
(E/Z) Equilibria, 16. Lone Electron Pair Donor Quality of the Imino Function: Synthesis and Reactivity of Sterically Strongly Congested Iminocyclopentanes
Authors: Knorr Rudolf , Hintermeyer‐;Hilpert Monika , Mehlstäubl Johann , Hoang Thi Phung , Neuner Brigitte , Bührer Petra 
Published: July 2007

Abstract2,6‐Dimethyl‐N‐(2,2,5,5‐tetramethylcyclopentylidene)aniline (4h) is obtained by permethylation; it forms salts (5) by N‐protonation. Its CN double bond is strongly shielded against nucleophilic attack and cannot be hydrolyzed. Nitration and bromination occur smoothly in the aromatic p‐position (12, 13), showing the directing power of the lone electron pair of the imino function. This π‐donor quality is assessed by probing weaker electrophiles and by qualitative competition experiments.
Light‐Induced [2 + 2] Cycloaddition of 2‐Morpholinoacrylonitrile to 1‐Naphthalenecarbonitrile
Authors: Düpp Dietrich , Erian Ayman Wahba , Henkel Gerald 
Published: July 2007

AbstractPhotoexcited 1‐naphthalenecarbonitrile (1) adds 2‐morpholinoacrylonitrile (2) in the [2 + 2] mode both at the C(1) – C(2) and C(7) – C(8) bond unidirectionally and with the formation of only one (3 and 4, respectively) of the two a priori possible stereoisomers in each case. The structure of 3 has been unambiguously confirmed by an X‐ray structural analysis.
Notizen/Notes Allenyl Enolates — A New Class of Chiral Ambident Nucleophiles, 2. Reaction with Iodine and Oxidizing Agents
Authors: Krause Norbert , Arndt Silke 
Published: July 2007

AbstractThe reaction of allenyl enolates, obtained by 1,6‐addition of lithium dimethylcuprate to 2‐en‐4‐ynoates 1a/b, with iodine is studied. Whereas the n‐butyl‐substituted enyne 1a gives a mixture of vinyl iodide 2a (48%) and methylated allene 3a (7%), the tert‐butyl‐substituted enyne 1b yields allene 3b (70%) exclusively. The products 2a and 3a are also obtained if Br2, O2, or CuCl2 are used to trap the allenyl enolate derived from 1a and Me2CuLi · LiI. These findings are discussed with the assumption that iodo‐allene 5 and the iodo‐containing Gilman cuprate [Me2Cu(I)Li2]2 are acting as intermediates.
Organometall‐Oxide — Höhervalente Derivate der d‐Metall‐Säuren, 6. Tris(3,5‐dimethyl‐1‐pyrazolyl)boranato‐substituierte Alkyl(dioxo)1‐, Methylenphosphoranyl(dioxo)1‐ und s̀1‐Allyl(dioxo)1‐Komplexe des Molybdäns und Wolframs
Authors: Sundermeyer Jörg , Putterlik Jürgen , Pritzkow Hans 
Published: July 2007

Organometallic Oxo Complexes — Highervalent Derivatives of the d‐Metal Acids, 6. — Hydrotris(3,5‐dimethyl‐1‐pyrazolyl)borato‐Substituted Alkyl(dioxo)1‐, Methylenephosphoranyl(dioxo)1‐, and s̀1‐Allyl(dioxo) Complexes of Molybdenum and TungstenTp*MoO2Cl (1) and Tp*WO2Cl (2) [Tp* = κ31‐HB(3,5‐Me2pz)3] react with trimethyl aluminium to form the corresponding dioxo(methyl) complexes Tp*MO2(CH3), MMo (3), W (4). An X‐ray crystal structure analysis of 3 is performed. The less oxidizing tungsten complex 2 is alkylated by Grignard reagents to yield alkyl complexes of the type Tp*WO2R 5–7 [RCH2SiMe3, CH2tBu and CH2C(Me)Ph2] and the s̀1‐2‐methallyl complex Tp*WO2(CH2CMeCH2) 8. Reactions of 2 with methylenephorphoranes R3PCH2 (RiPr, Ph) give transylidation products Tp*WO2(CHPiPr3) (9) and Tp*WO2(CH‐PPh3) (10). Hydrolysis of 10 leads to a trioxotungstate [Tp*WO3]– (11), stabilized by a hydroxyphosphonium cation.
Reaktionen von 1‐Phenyl‐3‐borolenen mit Aldehyden, Ketonen und Ketenen: Synthese von 1,2‐Oxaborolan‐Derivaten, 2,3‐anti‐1,3‐Diolen und ungesättigten β1‐Hydroxyalkylketonen
Authors: Herberich Gerhard E. , Englert Ulli , Wang Shaotian 
Published: July 2007

Abstract1‐Phenyl‐3‐borolenes CH2CR1CR1CH2BPh) (1a: R1H; b: R1Me) react with aldehydes R2CHO to give cis‐1,2‐oxaborolanes CH2CR1[CR1(CH2)]CR2R3OBPh (2, R2 = e.g. Me, Ph, CHCH2, tBu, CCl3, R3 = H). Yields are nearly quantitative. Stereoselectivities usually are 100% (but only 95% for R2CHCH2, 97% for R2Me). Oxidation with NaOH/H2O2 in THF affords homoallylic anti‐1,3‐diols HOCR2R31‐CR1[CR1(CH2)]CH2OH (3). An X‐ray diffraction analysis of 3a (R2p1‐tolyl) proves the assigned stereochemistries. Ketones R2R3CO react analogously. Ketenes R2CCO form 5‐alkylidene‐4‐vinyl‐1,2‐oxaborolanes (4), which tend to undergo double‐bond migration. Oxidation produces two types of β1‐hydroxylalkyl ketones R22CHCOC[(E)CHMe]CH2OH (5) and R22CHCOCMe[CMeCH2]CH2OH (6).
Lanthanoiden‐Komplexe, IV. Alkyl‐und Donor‐substituierte Cyclopentadienyl‐Komplexe des Neodyms
Authors: Herrmann Wolfgang A. , Anwander Reiner , Munck Florian C. , Scherer Wolfgang 
Published: July 2007

Complexes of the Lanthanides, IV[1]. — Alkyl‐and Donor‐substituted Cyclopentadienyl Complexes of NeodymiumNeodymium trichloride reacts with the potassium salt K(DoCH2CH2Cp) (2c, DoOMe; 2d, DoNMe2) of the functionalized cyclopentadienyls in THF to yield the sublimable homoleptic complexes Nd(DoCH2CH2Cp)3 (3c, d). Under the same conditions, K(iBuCp) (2a) yields the adduct Nd(i1‐BuCp)3(THF) (3a′), which is obtained free of THF by thermal treatment. The silylamide route is applied to synthesize the homoleptic neopentylcyclopentadienyl derivative Nd‐(NeopCp)3 (3b). The alkyl‐substituted complexes, particularly the isobutyl derivative, show a remarkable volatility. The first solvent‐free, monomeric complex of the type „LnCp2Cl”︁, namely Nd(Me2NCH2CH2Cp)2Cl (4), is obtained from NdCl3 and two equivalents of 2d.
Dreizentren‐oxidative Addition von Phosphor‐Yliden an Ru3(CO)12
Authors: Heineke Daniel , Scott Bohle D. , Vahrenkamp Heinrich 
Published: July 2007

Three‐Centre Oxidative Addition of Phosphorus Ylides to Ru3(CO)12Phosphorus ylides undergo oxidative addition to Ru3(CO)12 to yield a wide range of Ru3 clusters with triply bridging organic ligands derived from the ylides. Ph3PCH2 forms HRu3(CO)9(μ31‐Ph3P — CH — CO) (1) containing a phosphonio enolate. Ph3PCH — CHO yields a product mixture containing the phosphonio enolate‐bridged cluster and its PPh3 derivative 6, the phosphoniomethylidyne‐bridged compound H2Ru3(CO)9(μ31‐C — PPh3) (5), and the ketenylidene‐bridged compound H2Ru3(CO)8(PPh3)(μ31‐C — CO) (7). Thermal treatment converts the phosphonio enolate ligand (in 1) into the phosphoniomethylidyne ligand (in 5), and the latter into the ketenylidene ligand (in 7). With Ph3PCH — C(O)Me and Ru3(CO)12 ortho1‐metalated Ru3 derivatives 10, 11 of the phosphonio ketone R3P — C — C(O)Me are produced, and likewise with Ph3PCH — COOEt the ortho1‐metalated derivative 12 of the phosphonio ester R3P — C — CO2Et. Me3PCH — COOtBu is oxidatively added to form HRu3(CO)9(μ31‐Me3P — C — COOtBu) (13) bearing a phosphonio ester ligand. — The crystal structures of 6 and 13 are reported. The sequence of Ru3 clusters and the bonding modes of the μ3 ligands can be related to the surface reactions during Fischer‐Tropsch catalysis.
Rutheniumcluster‐vermittelter Aufbau von Kohlenstoff‐Ketten aus einem Phosphor‐Ylid und Alkinen
Authors: Heineke Daniel , Vahrenkamp Heinrich 
Published: July 2007

Ruthenium cluster‐Mediated Formation of Carbon Chains from a Phosphorus Ylide and AlkynesThe phosphorus ylide Me3PCH — C(O)Ph induces fragmentation of Ru3(CO)12 with formation of the dinuclear complex Ru2(CO)7(μ21‐HC_… CPhCH — C(O)Ph) (1a) with a σ,π1‐bound allyl ligand, together with its PMe3 derivative 1b. The latter inserts PhCCPh into the Ru — C s̀ bond to yield two isomeric complexes Ru2(CO)5(PMe3)[μ1‐CPh \documentclass{article}\pagestyle{empty}\begin{document}$ \underline \cdots $\end{document} CPh \documentclass{article}\pagestyle{empty}\begin{document}$ \underline \cdots $\end{document} CH — CPhCH — C(O)Ph] (3a, b) with a (σ,π1‐allyl,π1‐olefin)1‐coordinated six‐carbon chain ligand. With HCCPh 1b undergoes double insertion with formation of the complex Ru2(CO)4(PMe3)(μ1‐CHCPhCH — CPhCH — CPhCH — C(O)Ph] (4) containing an eight‐carbon chain ligand with (σ,π1‐allyl,π1‐olefin,π1‐olefin) coordination. The structure of 3a (and thereby indirectly the constitution of 1 and 4) was proved by an X‐ray structure determination.
Metall‐π1‐Komplexe von Benzolderivaten, XLI. Bis(η61‐anilin)chrom: Synthese, Redoxverhalten und Brønsted‐Basizität
Authors: Elschenbroich Christoph , Hoppe Stefan , Metz Bernhard 
Published: July 2007

Metal π Complexes of Benzene Derivatives, XLI[1]. — Bis(η61‐aniline)chromium: Synthesis, Redox Properties and Brønsted BasicityBis(η61‐aniline)chromium (6) has been prepared by protodesilylation of its N,N,N′,N′1‐tetrakis(trimethylsilyl) derivative 5, which is accessible by metal‐atom ligand‐vapor cocondensation (cc). Bis(η61‐dimethylaniline)chromium (3) is obtained directly from cc. The couples 3+/0 and 6+/0 feature the most negative redox potentials E1/2 ever reported for bis(arene)1‐metal complexes. According to EPR spectroscopy, applied to the radical cations 3+· and 6+· the site of oxidation is largely localized on the metal. The pH dependence of E1/2 is cast in Nerst‐Clark plots, whose breaks supply the pKs values of the mono‐and diprotonated forms of 3 and 6. η61‐Coordination to CrI increases the basicity of aniline by three pK units, whereas η61‐coordination to Cr1 effects a decrease by more than seven pK units. The first and second dissociation constants of the organometallic bis(ammonium) ions 3(H+)2 and 6(H+)2 differ by 2.7 pK units. This interval reflects the interaction of the two basic centers in 3 and 6 which approaches that of p1‐phenylenediamine. Thus, conjugation across the bis(η61‐arene)chromium unit is virtually uninhibited.
Reaktionen Pentafluorethyl‐substituierter Bicyclo[2.1.1]hexan‐Derivate
Authors: Kirmse Wolfgang , Wonner Aribert 
Published: July 2007

Reactions of Pentafluoroethyl‐Substituted Bicyclo[2.1.1]hexane DerivativesThe effect of inductively electron‐withdrawing substituents on the generation of 2‐bicyclo[2.1.1]hexyl cations was probed by means of pentafluoroethyl groups. 2‐Pentafluoroethyl‐2‐bicyclo[2.1.1]hexyl brosylate (4a) and triflate (4b) were found to rearrange with formation of the analogous 1‐pentafluoroethyl‐2‐bicyclo[2.1.1]hexyl sulfonates 5a, b. Solvolytic displacement did not compete with the rearrangement but occurred on 5b at elevated temperatures. Deuterium labels revealed that the rearrangement proceeded stereospecifically, with the sulfonate departing and rebonding on the same side of the molecular plane. Complete inversion was observed during solvolysis of 5b in aqueous dioxane while some retention (16%) occurred in trifluoroacetic acid. Predominant inversion even with the analogous diazonium ion in water attests to the reluctant formation of 1‐pentafluoroethyl‐2‐bicyclo[2.1.1]hexyl cations. Solvolysis rates of 4a, b and 5b were in close agreement with those of the analogous cyano derivatives, thus confirming that the resonance interaction of α1‐cyano groups with carbocations is small.
syn1‐Periplanar Bisazo Skeletons — Syntheses and Reactions with Carbonylmetal Complexes
Authors: Bahr Nicolaus , Beckmann Eberhard , Mathauer Klemens , Hunkler Dieter , Keller Manfred , Prinzbach Horst , Vahrenkamp Heinrich 
Published: July 2007

AbstractPreparatively useful synthesis for the novel, relatively mobile polycyclic syn1‐periplanar bisazo polycycles 4 and 5 are based on hydrazine condensation with readily available dienedione 6 and acid‐catalyzed rearrangement of bisurazole 12, respectively. In the preferred “closed” and “open” conformations of 4 and 5 the NN bonds are 314 and 496 pm, respectively, apart (MMX). From the reactions of 4 and 5 with carbonyliron and ‐ruthenium compounds, complexes are derived which are typical of monoazo ligands [4 · Fe(CO)4  20, 4 · Fe2(CO)721, 4 · Fe3(CO)922, 4[Fe2(CO)6]223, 4 · Ru3(CO)9 · 24, 5 · [Fe2(CO)6]2  25, 5 · Fe2(CO)6 · Fe3(CO)9  26]. For 21, 23 and 26 crystal structure analyses were performed, confirming i.a. in 26 the unique presence of a Fe2(CO)6 and a Fe3(CO)9 fragment attached to two azo units of the same molecule.
Azaazulene als Dienophile in der Diels‐Alder‐Cycloaddition mit 3,6‐Bis(trifluormethyl)1‐1,2,4,5‐tetrazin
Authors: Frenzen Gerlinde , Massa Werner , Reimers Uwe , Seitz Gunther 
Published: July 2007

Azaazulenes as Dienophiles in the Diels‐Alder Cycloaddition with 3,6‐Bis(trifluoromethyl)1‐1,2,4,5‐tetrazineThe LUMO‐diene‐controlled [4 + 2] cycloaddition of the azaazulenes 6 and 17 with the tetrazine 1, one of the most reactive diazadienes “with inverse electron demand”, are described. Like azulene (2) the azaazulenes 6a, b react with 1 – probably by a two‐step mechanism via the dipolar species 7 – to yield the adduct 8; N2 elimination leads to 9, which rearranges to the pyridazo[4,5‐c]quinoline 13 and the azine‐substituted 1‐azaazulene 12. In a rather complex reaction sequence the 2‐azaazulene 17 forms the salt 18; the crystal structure of 18 has been determined by X‐ray diffraction methods.
Medium‐Sized Cyclophanes, 25. Bromination of [2.n]Metacyclophan‐1‐enes and Isolation of Two Isomers of 1‐Bromo[2.n]metacyclophan‐1‐enes
Authors: Yamato Takehiko , Matsumoto Jun‐Ichi , Ide Seiji , Suehiro Kazuaki , Kobayashi Kazumasa , Tashiro Masashi 
Published: July 2007

AbstractBromination of dimethyl[2.3]metacyclophan‐1‐ene (1b) with bromine affords the cis adduct 6b resulting from the addition to the bridging double bond; a similar reaction of dimethyl[2.4]metacyclophan‐1‐ene (1c) gives a mixture of the cis and trans adduct formed by the addition to the bridged double bond along with the products containing a brominated internal methyl group. On the other hand, bromination of dimethy1[2.n]metacyclophan‐1‐enes (1) with benzyltrimethylammonium tribromide affords exclusively the product of the cis addition 6 to the bridged double bond. Treatment of [3.2]metacyclophane 6b with potassium tert1‐butoxide in refluxing tBuOH for 1 h gives the dehydrobrominated product (E)‐8b in 95% yield; a similar reaction of [4.2]metacyclophane 6c furnishes two isomers, (E)‐8c and (Z)‐8c, of 1‐bromo[2.4]1‐metacyclophan‐1‐ene along with [2.4]metacyclophan‐1‐one 9c in 20% yield. The characterization and the reaction pathway of these products are discussed.
Multistep Redoxsystems, LX. 1,4,5,8‐Tetraoxo‐1,4,5,8‐tetrahydrothianthrene: Synthesis, Structure, and Spectroelectrochemical Properties
Authors: Hünig Siegfried , Sinzger Klaus , Bau Robert , Metzenthin Tobias , Salbeck Josef 
Published: July 2007

AbstractThe synthesis, structure, cyclovoltammetric and spectroelectrochemical data of 1,4,5,8‐tetraoxo‐1,4,5,8‐tetrahydrothianthrene (2a) are presented. A relation between the positive partial charge at the sulfur atom and the dihedral angle at the SS axis is discussed on the basis of semiempirical MO calculations.