bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photoextrusion von molekularem Stickstoff aus 5‐Alkyliden‐4,5‐dihydro‐1H‐tetrazolen mit Vinyl‐ oder Phenyl‐Substituenten. (E)‐Aziridinimine und neuartige Produkte
Authors: Quast Helmut , Hergenröther Thomas 
Published: July 2007

Photoextrusion of Molecular Nitrogen from 5‐Alkylidene‐4,5‐dihydro‐1H‐tetrazoles Substituted by Vinyl or Phenyl Groups. (E)‐Aziridinimines and Novel Products[1]Direct irradiation of deuterated hydrocarbon solutions of the alkylidenedihydrotetrazoles 11 affords quantitative yields of the aziridinimines (E)‐ and (Z)‐12, besides molecular nitrogen, with (E)/(Z) ratios ranging from 95:5 (12e, ‐40°C) to >99:<1 (12 c, 20°C). From 14, which carries two different groups at the nitrogen atoms, equal amounts of the isomers 13 and 15 are obtained, again with a strong predominance of the (E) diastereomers. The structures of the aziridinimines have been elucidated by their NMR spectra and, in the case of 13 and 15, by [2 + 1] photocycloreversion into the corresponding isocyanides 16 and imines 17, which is induced by selective irradiations with light of shorter wavelengths. Photolysis of the alkenlidenedihydrotetrazole 18c at ‐40°c affords the 2‐imino‐3‐vinylaziridine 20c which decomposes at higher temperatures. Irradiation of 18c at 20°C or partial photolysis at ‐40°C followed by warming to 20°C furnishes the spirocyclic product 19c. The analogous products 19a and b are obtained from 18a and b. The vinyl compound 19a very slowly isomerizes to the ethylidene compound 23 by a proton 1,3‐shift. The spirocyclic structures 19 and 23 are based on mass and NMR spectra including 1H,1H and 13C1H COSY and extensive 1,1H decoupling experiments. The formation of the spirocycles 19 is interpreted in terms of a photoextrusion of molecular nitrogen from 18 to afford 3‐vinylaziridinimines 20 which, at higher temperatures, rearrange to the 1,3‐diazabutadienes 24 by a hydrogen homo[1,5]‐ or homo[1,7]‐shift. [4 + 2] Cycloaddition of 24 to unchanged 18 eventually yields the spirocycles 19.
Pinzettenförmige Kohlenwasserstoffe
Authors: Vögtle Fritz , Koch Herbert , Rissanen Kari 
Published: July 2007

Tweezer‐Shaped Hydrocarbons1,8‐Bis[(arylethynyl)phenyl]‐ and ‐[(arylethenyl)phenyl]anthracenes of type I (e.g. 9, 6a) and 1,8‐bis{[(arylethynyl)phenyl]‐ethynyl}‐ and ‐{[(arylethenyl)phenyl]ethynyl}anthracenes of type II (e.g. 16, 13) were synthesized for the first time. Their hydrocarbon framework is formed by Grignard coupling and by Hagihara coupling, respectively. An X‐ray analysis of 13 exhibits an approximate planar skeleton, only one aromatic ring showing a considerable deviation from that plane (Figure 2). The UV and fluorescence properties are discussed. In spite of their preorganized and rather rigid tweezer‐shape the new hydrocarbons do not seem to use their multiple bonds for the cooperative binding of transition metal cations.
Neue extrem deformierte (Biphenylen‐)Kohlenwasserstoff‐Gerüste
Authors: Schulz Jochen E. , Rissanen Kari , Vögtle Fritz 
Published: July 2007

New Extremely Deformed (Biphenylene)Hydrocarbon SkeletonsThe tetracyclic carbon skeleton 2‐oxo[3](1,8)biphenylenophane (4) was synthesized by cyclization of a mixture of the bis(bromomethyl) compounds 7a, b with p‐tolylsulfonylmethyl isocyanide. 2‐Hydroxy[3](1,8)biphenylenophane (5) and the [3](1,8)biphenylenophane hydrocarbon 6 were obtained by reduction of 4 with LiAlH4 and NaBH4, respectively. X‐ray analyses of 4 and 6 illustrate the dramatic deformation of bond lengths and angles in these molecules.
Inter‐ and intramolecular hetero diels‐alder reactions, 40. Effect of high pressure on the stereoselectivity of intermolecular hetero diels‐alder reactions
Authors: Tietze Lutz F. , Hübsch Thomas , Oelze Jens , Ott Christian , Tost Winfried , Wörner Gabriele , Buback Michael 
Published: July 2007

AbstractThe hetero Diels‐Alder reaction of enamino ketone 1 with the vinyl ethers 7–11 leading to the dihydropyrans 12a–e and 13a–e is studied in dichloromethane under high pressures up to 7 kbar. The kinetics is measured by on‐line FT‐IR spectroscopy up to 3 kbar. For the first time individual rate coefficients kcis and ktrans have been determined. Pressure‐averaged activation volumes, magnified image, for the overall reaction leading to the formation of the two diastereomers in dichloromethane solution between ‐(19.1 ± 1.7) and ‐(25.4 ± 1.6) cm3 mol−1 are measured. The corresponding activation enthalpies, ΔH‡, are between (62.2 ± 1.6) and (76.3 ± 3.6) kJ mol−1. The cycloaddition shows a remarkable increase in diastereoselectivity in favour of the cis adducts 12a–e toward higher pressure. The pressure‐averaged differences in activation volume, magnified image, for the two reaction pathways leading to cis and trans diastereomers are found to be between ‐(4.5 ± 0.3) and ‐(6.9 ± 0.7) cm3 mol−1. The corresponding differences in activation enthalpy, δδH≠, are between ‐(4.7 ± 1.4) and ‐(9.9 ± 1.6) kJ mol−1. Combination of the overall rate coefficient k = kcis + ktrans for the reaction leading to the two diastereomers with the measured product ratio, ccis/ctrans, which is identified with the ratio of the rate coefficients kcis/ktrans, yields the individual coefficients kcis and ktrans. The rate coefficient kcis is strongly influenced by the steric demand of the substituents on both diene and dienophile whereas ktrans varies to a smaller extent, and the observed changes appear to be mainly due to the electronic properties of the substituents.
α‐Oxygen‐Substituted Organolithium Compounds and Their Carbenoid Nature: Calculations of the Configurational Stability and of LiCH2OH Model Structures, Crystal Structure of Diphenyl(trimethylsilyloxy)methyllithium · 3 THF, and the Stereochemistry of the (Reverse) Brook Rearrangement
Authors: Boche Gernot , Opel Achim , Marsch Michael , Harms Klaus , Hallera Friederike , Lohrenz John C. W. , Thümmler Christina , Koch Wolfram 
Published: July 2007

AbstractThe comparatively high configurational stability of α‐oxygen‐substituted organolithium compounds is confirmed by ab initio calculations [MP2/6–311 + + G(d,p)]. Model calculations of the LiCH2OH structures 21A–D (MP2/6–31G(d)//3–21G and MP2/6–311 + + G(d,p)//MP2/6–311 + + G(d,p)) are in agreement with recently determined crystal structures of α‐oxygen‐sub‐stituted organolithium compounds. They also suggested the preparation of a new structural type (21C) which has been verified by means of diphenyl(trimethylsilyloxy)methyllithium · 3 THF (24 · 3 THF) as shown by X‐ray crystallography. The lengthening of the CO bonds in all four α‐oxygen‐sub‐stituted organolithium compounds known to date contrasts strongly with the wealth of structural data from organolithium compounds α‐substituted with “typical” acceptor substituents: on lithiation the carbon‐acceptor bond length in these compounds is always shortened. This difference is in agreement with a carbenoid character of α‐oxygen‐substituted organolithium species. Finally, the crystal structure of 24 · 3 THF serves as a model for the surprising stereochemistry of the (reverse) Brook rearrangement.
Photoinduced electron transfer in porphyrin‐quinone cyclophanes, 5. Quinone‐porphyrin‐quinone and quinone‐porphyrin‐donor cyclophanes: Syntheses, structures and electron‐transfer‐related properties
Authors: Staab Heinz A. , Weiser Jürgen , Baumann Ernst 
Published: July 2007

AbstractTo study the structure dependence of photoinduced electron transfer between porphyrins and quinones the concept of a new family of porphyrin‐quinone cyclophanes with vertical arrangements of porphyrin and quinone units is presented. The syntheses of the quinone‐porphyrin‐quinone cyclophane 1, the prototype of this series, and of the quinone‐porphyrindonor cyclophanes 12 and 14 are described. Spectroscopic data are discussed with regard to the structures involved and in relation to electron‐transfer reactions occurring in these systems.
Photodecarbonylation of 2(3H)‐thiophenones
Authors: Hinrichs Heiko , Margaretha Paul 
Published: July 2007

AbstractLight‐induced (300 nm) loss of CO converts 2(3H)‐thiophenones to either thietes, thiophenes, homothiophenes, or thiopyrans, the product distribution being strongly influenced by the alkyl substitution pattern on the thiolactone.
Cobaltkomplexe mit As4‐Liganden
Authors: Scherer Otto J. , Pfeiffer Karl , Wolmershäuser Gotthelf 
Published: July 2007

AbstractCobalt Complexes with As4 LigandsThe reaction of [Cp*Co(μ‐CO)]2(Co = Co) (1) with As4 in boiling toluene gives the cobalt complexes [Cp*Co(CO)(η1:1‐As4)] (2), [{Cp*Co(CO)}2(μ‐η1:1:1:1‐As4)] (3), exo,endo‐[Cp*Co(μ‐η4:1:1‐As4)Co(CO)Cp*] (4a, b), and [Cp*Co(μ‐η2:2‐As2)]2 (5), Cp* = C5Me5. 2,3, and 4b have been characterized by X‐ray structure analyses. With respect to the mechanism of this reaction the successive cleavage of two, three, and four As–As bonds of yellow arsenic, As4, has been proved.
Chiral Epoxides as Building Blocks for Ethylene‐Bridged ansa‐Metallocene Complexes – Synthesis of C1‐Symmetrical Zirconocene Dichlorides with Two Different Cyclopentadienyl Units
Authors: Rieger Bernhard , Steimann Manfred , Fawzi Riad 
Published: July 2007

AbstractEpoxystyrene undergoes ring opening on treatment with tetraphenylcyclopentadienyl‐ and fluorenyllithium to give the corresponding chiral alcohols 3 and 4 in high yield. Their trifluoromethanesulfonate derivatives 5 react with one equivalent of cyclopentadienylsodium to form the ligand precursors 1‐cyclopentadienyl‐1‐phenyl‐2‐(tetraphenylcyclopentadienyl)ethane (L1H2) and 1‐cyclopentadienyl‐2‐(9‐fluorenyl)‐1‐phenylethane (L2H2). The zirconocenes L1ZrCl2 (7a) and L2ZrCl2 (7b) are prepared from the dilithio salts L1Li2 and L2Li2, respectively. A low‐temperature X‐ray structure investigation of complex 7a demonstrates the chiral arrangement of the four phenyl substituents of the tetraphenylcyclopentadienyl (C5Ph4) unit. A 1H‐NMR study shows that the phenyl groups rotate rapidly on the NMR time scale at room temperature. The dependence of phenyl rotation on temperature is discussed.
Alkylsilber‐ und Alkylgold‐Reagenzien, II. Cyano(methyl)argentate: Spektroskopie, Selektivität als Methylierungsreagenzien, Vergleich mit anderen Methylsilber‐Reagenzien
Authors: Kauffmann Thomas , Neiteler Christel , Robbe Sonja 
Published: July 2007

AbstractAlkylsilver and Alkylgold Reagents, II[1]. – Cyano(methyl)argentates: Spectroscopy, Selectivity as Methylating Reagents, Comparison with Other Methylsilver ReagentsAs the first examples of a new type of Ag complex the cyanoargentates MeAg(CN)Li (1), Me2Ag(CN)Li2(2), MeAg‐(CN)MgBr (3), and Me2Ag(CN)(MgBr)2(4) were prepared in solution or suspension by transmetallation of MeLi or MeMgBr with AgCN. Compared to AgBr‐derived reagents, such as MeAg · MgBr2(5) and Me2AgMgBr (6), the cyano(methyl)‐argentates are clearly less sensitive to light. According to the IR spectrum, the Ag atom of2is connected with the cyano group. The13C‐NMR spectra of2, 4, 5, and6furnish proof of the Ag – Me group in these compounds and points to the partial structure Ag – Me – Mg in4, 5, and6. – Complexes2(stable up to 20°C),4, 5, and6methylate the ketoaldehyde13with high selectivity at the aldehyde group (best yield with4). 4, 5, and6exhibit high cheleselectivity in the reaction with the hydroxy diketone22(best yield with4) and comparable intermolecular competitive systems.2and6methylate 11,12‐epoxy‐2‐deodecanone (28) with virtually complete regioselective ring opening to give 11‐hydroxy‐2‐tridecanone (29). In contrast to Me2Cu(CN)Li2(7) and Me2CuMgBr, the analogous reagents Me2Ag(CN)Li2(2) and Me2AgMgBr (6) methylate styrene oxide (32), and6also methylates α‐methylstyrene oxide (36) in α‐position to the phenyl residue with high selectivity, yielding nearly exclusively 2‐phenylpropanol (33) or 2‐methyl‐2‐phenylpropanol (37), respectively. The selective „α attack„ of Ag reagents is explained by fixation of the reagent to the phenyl residue of32and36in the first reaction step.
The Mechanistic Diversity of the Thermal and Photochemical Decomposition of Bis(phenylphosphonoyl)Peroxides: Concerted Polar, Homolytic, and Electron‐Transfer Processes On the Reactivity of (Phenylphosphonoyl)oxyl Radicals
Authors: Korth Hans‐Gert , Lommes Petra 
Published: July 2007

AbstractThe thermal and photochemical decomposition of the first bis(phenylphosphonoyl)peroxides, dioxybis[(n‐butoxy)phenyl‐phosphane oxide] (5), and dioxybis[(phenoxy)phenylphosphane oxide] (6) has been studied in various solvents by 1H‐, 13C‐, and 31P‐NMR spectroscopy, laser flash photolysis (LFP), and ESR spin‐trapping experiments. Kinetic studies reveal at 20°C a ca. 270 times slower thermal decay for 5 than for 6, which primarily results from a lower A factor rather than differences in the activation energies. The thermal decay of 5 occurs predominantly by a novel, presumably concerted polar rearrangement with formation of a thermally unstable, mixed phosphonoyl‐phosphoryl anhydride. Photolysis of 5 induces homolytical cleavage of the peroxy bond with release of [(n‐butoxy)phenylphosphonoyl]oxyl radicals 7. Radical 7 is characterized by a broad, transient UV/Vis absorption spectrum in the 400 to >700 nm range (λmax ca. 580 nm), as has been demonstrated by 248‐nm LFP of 5 in acetonitrile solution. The short lifetime of this absorption indicates an extremely high reactivity (in hydrogen abstraction and addition) of this electrophilic radical. The thermal and photochemical decomposition of peroxide 6 leads to a virtually identical product distribution, suggesting O–O bond cleavage to be the major initial reaction under both conditions. LFP at 248 and 308 nm of a solution of 6 in acetonitrile initially produces a weak, broad absorption at ca. 500 nm and stronger bands at 280 and 400 nm. The highly transient 500‐nm absorption is assigned to the [(phenoxy)phenylphosphonoyl]oxyl radical 8, the other bands are attributed to the phosphonoyloxy‐substituted benzene radical cation 8Z. The formation of this species can be explained in terms of electron transfer in the first‐formed oxyl radical 8 and/or the intact peroxide 6, followed by cleavage of the peroxy bond. The decay of 8Z is accompanied by the build‐up of the absorption spectrum of a 1,4‐dioxy‐substituted biphenyl radical cation.
Medium‐Sized Cyclophanes, 20. Synthesis and Conformational Studies of syn‐ and anti‐Dihydroxy[n.2]metacyclophanes
Authors: Yamato Takehiko , Matsumoto Jun‐Ichi , Tokuhisa Kiwamu , Kajihara Masami , Suehiro Kazuaki , Tashiro Masashi 
Published: July 2007

Abstractsyn‐ and anti‐Dimethoxy[n.2]metacyclophanes 9 are obtained by pyrolysis of the corresponding anti‐sulfones 8, which are prepared by the reaction of 1,n‐bis[3‐(chloromethyl)‐2‐methoxyphenyl]alkanes 6 with Na2S in ethanol under the high dilution conditions, followed by the oxidation of the obtained thiametacyclophanes 7 with m‐chloroperbenzoic acid. Demethylation of anti‐dimethoxy[n.2]metacyclophanes anti‐9 with BBr3 in dichloromethane affords the corresponding anti‐dihydroxy[n.2]metacyclophanes anti‐10. On the other hand, demethylation of syn‐dimethoxy[3.2]‐syn‐ 9b and ‐[4.2]meta‐cyclophane syn‐9c gives syn‐dihydroxy[n.2]metacyclophanes syn‐10b, c, but syn‐dimethoxy[5.2]‐syn‐9d and ‐[6.2]metacyclophane syn‐9e are converted into the corresponding anti‐dihydroxy[n.2]metacyclophanes anti‐10d, e. AlCl3 · CH3NO2‐catalyzed de‐tert‐butylation of tert‐butyl‐syn‐ and ‐anti‐dihydroxy[3.2]‐ and ‐[4.2]metacyclophanes syn/anti‐10b, c has been carried out in benzene to give the desired metacyclophanes anti‐11a–c and syn‐11c except syn‐dihydroxy‐[3.2]metacyclophane syn‐11b which is converted into 8,17‐epoxy[3.2]metacyclophane 13. The assignment of syn and anti conformations has been confirmed by 1H‐NMR analyses and X‐ray diffraction studies. The dynamics of the ring inversion and UV spectra are also discussed.
Synthese und Komplexbildung eines neuen makrocyclischen Liganden mit drei Benzimidazolin‐2‐on‐Einheiten
Authors: Weber Edwin , Piel Manfred , Buschmann Hans‐Jürgen , Cleve Ernst 
Published: July 2007

AbstractSynthesis and Complex Formation of a New Macrocyclic Ligand Incorporating Three Benzimidazolin‐2‐one Units The new macrocyclic ligand 1 composed of three benzimidazolin‐2‐one‐1,3‐diyl and three propane‐1,3‐diyl building blocks has been synthesized. Complex formation constants in water involving Li+, Na+, K+, Mg2+ Ca2+, Si2+, and Ba2+ are discussed. The most stable complex is formed with Ca2+.
Synthese von [n.1.1]Propellanen (n = 2, 3, 4)
Authors: Fuchs Josef , Szeimies Günter 
Published: July 2007

AbstractA facile access to the parent [n.1.1]propellanes 2, 3 and 4 is presented. Lithiation of methallyl alcohol with the BuLi/TMEDA complex and reaction of the organometallic intermediate 8 with paraformaldehyde, ethylene oxide, or oxetane affords the diols 9 which are converted via the dichlorides 10 into the tetrahalides 11. The cyclization of 11 to the corresponding propellanes is effected with 2 equiv. of MeLi or BuLi via the bromobicyclo[1.1.0]butanes 12. As expected, 2 cannot be isolated; its formation is deduced from the structure of the consecutive products.
Konkave Farbstoffmoleküle vom Triphenylmethan‐Typ
Authors: Berscheid Ralf , Nieger Martin , Vögtle Fritz 
Published: July 2007

AbstractConcave Triphenylmethane DyestuffsTriply‐ and doubly‐bridged as well as dye molecules (2, 18, and 11) connected by a single chain were prepared including the corresponding phenolphthalein and fluorescein derivatives (24a–c). The concave orange‐coloured triphenylmethane dye 2 exhibits solvatochromic and halochromic effects different to nonmacrocyclic reference substances. The triphenylmethane dyes are reversibly transferred to the corresponding uncoloured macrocycles by changing the pH. The structures of 9, 22b, and 22c were confirmed by X‐ray analyses.
Pressure‐Induced Diastereoselectivity in Photochemical [2 + 2] Cycloaddition Reactions
Authors: Buback Michael , Bünger Joachim , Tietze Lutz F. 
Published: July 2007

AbstractPhotochemical [2 + 2] cycloaddition reactions under high pressure of cyclopentenone 1a or cyclohexenone 15, as well as of 1a or 3‐substituted cyclopentenones 1b–d with cyclopentene (2), and of 1b with 3,3‐dimethyl‐1‐butene (18) are described. Whereas the pressure dependence on the regioselectivity in the photoaddition of 1a and 15 is very small, δδV≠ values up to 2.0 ± 0.3 cm3 · mol‐1 have been found for the diastereoselectivity in the reactions of 1a–d with 2 and of 1b with 18.
2,6‐Dimethyl Semibullvalene‐2,6‐dicarboxylates
Authors: Quast Helmut , Witzel Alexander , Peters Eva‐Maria , Peters Karl , Schnering Hans Georg Von 
Published: July 2007

AbstractThe enolized β‐oxo ester 9 is reduced by NaB(CN)H3 in weakly acidic methanol solution to afford an almost quantitative yield of a mixture of diastereomeric β‐hydroxy esters 10. On treatment with phosphorus oxychloride in pyridine, 10 is converted into a mixture of the β‐chloro esters exo‐11, endo‐11, exo‐12, endo‐12, and 13 which is separated in part by chromatography. Sodium methoxide in methanol eliminates hydrogen chloride from the crude mixture of β‐chloro esters producing the α,β‐unsaturated ester 7a in 84% yield based on 9. – Acid‐catalysed equilibration of the known vinyl sulphides C2‐ and Cs‐15 is carried out on large scale furnishing a 73:27 ratio of C2‐ and Cs‐15. This mixture is oxidized to the sulphones C2‐ and Cs‐16 which are allowed to react with sodium cyanide supported on aluminium oxide affording the α,β‐unsaturated dinitrile 17 which is isolated by chromatography. Thus, 17 is now available on a 30‐g scale. Methanolysis of 17 by a prolonged treatment with hydrogen chloride in methanol followed by hydrolysis of the Pinner salt leads to 7b. – Both α,β‐unsaturated esters 7a and b are readily brominated at the allylic positions by N‐bromosuccinimide to yield the γ,γ′‐dibromo esters 19a and b. Zinc‐copper couple in tetrahydrofuran converts 19a and b into the semibullvalenedicarboxylates 2a and b. While 2a is persistent only in dilute solutions, thus frustrating all attempts at its isolation, 2b exhibits considerable stability in solution and forms lemon‐coloured crystals. The semibullvalenedicarboxylates 2a and b undergo a very rapid degenerate Cope rearrangement in solution. In addition, 2b exhibits reversible thermochromism in both solution and solid state. The structures of the new compounds are based on spectroscopic evidence, including mass, IR, and NMR spectra. The configurations of exo‐11, exo‐12, 19a and b are established by X‐ray diffraction analyses.
Diphenyl‐ and Bis(phenylethynyl)semibullvalenes
Authors: Quast Helmut , Carlsen Jürgen 
Published: July 2007

AbstractThe 2,6‐ (6b, c) and 3,7–substituted 1,5–dimethylbicyclo‐[3.3.0]octadienes C2‐ and Cs‐9b and c are brominated by N‐bromosuccinimide in the allylic positions to afford the dibromides 7b, exo,exo‐7c, 10b and c, respectively. An excess of N‐bromosuccinimide converts 10b into the unsymmetrical tetrabromide 11. On chromatography over silica gel, exo,exo‐7c is epimerized to endo,endo‐7c, while methanolysis occurs on reversed–phase chromatography yielding the dimethoxy compound 8. Under ultrasonic irradiation, the zinc–copper couple converts the bromides 7b, exo,exo‐7c, 10c, and 11 into the semibullvalenes 1b, c, 2c, and 12 which are persistent in dilute solutions when atmospheric oxygen is strictly excluded. The UV/Vis spectra of 1b, c, 2c, and 12 have been recorded during reversed–phase HPLC on a Bruker ChromScan detector. Notwithstanding the absence of a classical chromophor, 1c does absorb at no less than 450 nm.
Transition–Metal–Diene Complexes in Organic Synthesis, 12. Regio‐ and Stereoselectivity of Electrophilic Substitutions of Arylamines by Tricarbonyliron–Complexed Cyclohexadienylium Cations and Oxidative Cyclizations to Carbazoles
Authors: Knölker Hans–Joachim , Bauermeister Michael , Pannek Jörn–Bernd 
Published: July 2007

AbstractElectrophilic substitutions of donor–substituted arylamines using tricarbonyliron–complexed cyclohexadienylium cations lead regio‐ and stereoselectively to the corresponding tricarbonylcyclohexadieneiron complexes. The C–C bond formations occur regioselectively in the ortho position with respect to the amino group with arylamines containing a substituent in the para position. The initially formed N‐alkylated arylamine (kinetic product) is shown to rearrange in an intermolecular process to the C‐alkylated arylamine (thermodynamic product). The reported oxidative cyclization to 3–methylcarbazole yields large amounts of the demetalated ligand. However, oxidative cyclization to 3–methoxycarbazole is possible under mild reaction conditions (room temperature) by using especially activated manganese dioxides.
1‐Alkynyl Disulfides: Their Characterization and Their 1‐Thiapropargyl — 3‐Thiaallenyl Rearrangements
Authors: Nørkjær Kim , Senning Alexander 
Published: July 2007

AbstractThe synthesis of novel 1‐alkynyl disulfides 1 is described together with their 1‐thiapropargyl — 3‐thiaallenyl rearrangement and a [1,3]‐sigmatropic shift of 1‐alkynyl amino disulfides, followed by rearrangement of the aminothio‐substituted thioketenes so formed.