bluuebunny/crossref_metadata_2025_split huggingface dataset:
Elektrochemische und spektroskopische Charakterisierung von N,N′‐Dialkylchinoxalinium‐Redoxsystemen
Authors: Schulz Andreas , Kaim Wolfgang 
Published: July 2007

Electrochemical and Spectroscopic Characterization of N,N′‐Dialkylquinoxalinium Redox SystemsThe outstanding position of the 1,4‐isomer, quinoxaline, among the diazanaphthalenes is confirmed by comparing LUMO energies from HMO perturbation calculations. Diquaternary salts [(R+)2(quin)](X−)2, R = Me, Et; quin = quinoxaline, 2,3‐ and 6,7‐dimethyl‐ and 2,3,6,7‐tetramethylquinoxaline, X− = BF4‐ or SbCl6‐ (4a – g), were isolated and characterized as compounds which are sensitive to reduction and hydrolysis. Cyclic voltammetry of the two‐step redox systems of the Weitz type showed two reversible one‐electron reductions with an extraordinarily stable radical cation intermediate (lg Kc 12). The redox potentials are less negative than those of the 4,4′‐bipyridinium systems but also less positive in comparison to the values of N,N′‐dialkylphenazinium compounds. The radical cation intermediates which include a TCNQ− salt cannot only be characterized by ESR, but also by absorption spectroscopy in comparison to the respective dications.
Borogranyle, II1,2) Darstellung, Struktur und Reaktionen von Lithium‐[cyan(triphenyl‐phosphoranyliden)methyl]trihydroborat(‐1)
Authors: Bestmann Hans Jürgen , Röder Thomas , Bremer Matthias , Löw Dieter 
Published: July 2007

Organoboron Compounds, II1,2) – Preparation, Structure, and Reactions of Lithium [Cyano(triphenylphosphoranylidene)‐methyl]trihydroborate(‐1)(Cyanomethylene)triphenylphosphorane (5) adds borane (from 2) with formation of phosphorane‐borane 6, which cannot be rearranged. 6 reacts with butyllithium to afford a crystalline lithium compound 9, which contains four tetrahydrofuran molecules. The X‐ray structure analysis of 9 is reported, 9 is acting as a reducing agent towards halogeno and carbonyl compounds.
Trioxypentafulvenes, 2 synthesis of 1‐substituted 2,3,6‐trioxypentafulvenes
Authors: Victory Pedro , Alvarez‐Larena Angel , Beti Carlos , Borrell Joséa I. , Batllori Xavier , Córdoba Carlos 
Published: July 2007

AbstractSyntheses of 2,3,6‐trioxypentafulvenes with a free position at the ring are described, in which the protection of the C‐3 hydroxy group as methoxy or acetoxy derivative has been required. The difference in the behavior of the title compounds in relation to the previously reported 1,4‐disubstituted 2,3,6‐trihydroxypentafulvenes 2a‐e, which only exhibit enol forms, is discussed and attributed to the disappearance of the push‐pull system formed by the C‐3 enol group and the C‐4 electron‐withdrawing substituent.
Regio‐, Diastereo‐, and Enantioselective Synthesis of vic‐Diols via α‐Silyl Ketones According to the SAMP/RAMP Hydrazone Method
Authors: Enders Dieter , Nakai Shiro 
Published: July 2007

Abstractα‐Silylated ketones 5 or 10 of high enantiomeric purity (ee ≥ 90%) are easily available by silylation or silylation/alkylation of ketones 1 or 6, resp., according to the SAMP/RAMP hydrazone method. Reduction of 5 or 10 with L‐selectride™, followed by oxidative cleavage of the C–Si bond, leads to vic‐diols 11–13 with high diastereoselectivity (de ≥ 90%) and without racemization. The stereoselectivity of the reduction depends on the structure of the α‐silyl ketones 5 or 10, the reducing reagents, and the solvents used.
Synthese und Struktur eines Imino(phosphoranylidenmethyl)phosphans: Ein neues Hetero‐Allyl‐Anion
Authors: Krüger Uwe , Pritzkow Hans , Grützmacher Hansjörg 
Published: July 2007

Synthesis and Structure of an Imino(phosphoranylidenemethyl)phosphine: A New Hetero Allyl AnionReaction of the (dichlorophosphinyl)methylphosphonium salt 1 with three equivalents of sodium bis(trimethylsilyl)amide (2) in THF at – 78°C leads to the P‐(phosphoranylidenemethyl)‐substituted iminophosphine 4. Compound 4 is probably formed via 3 by 1,3‐silyl migration. According to an X‐ray analysis, 4 can be described as a hetero allyl anion with a 3‐ center‐4‐electron bond C1–P1–N1. Oxidative addition of sulfur or selenium results in formation of the imino(thioxo)phosphorane 8 or imino(selenoxo)phosphorane 9.
Synthesis and Dynamic Behaviour of [7]‐ and [8]Metacyclophanes
Authors: Takeshita Michinori , Tsuge Akihiko , Tashiro Masashi 
Published: July 2007

AbstractThe synthesis and structure of [7]‐ and [8]metacyclophanes 2, 4 are described. The reductive ring opening of the thiophene rings of [2]metacyclo[2](2,4)‐ and ‐(2,5)thiophenophanes 1 and 3 by Raney‐Ni affords the corresponding [7]‐ and [8]metacyclophanes 2 and 4, respectively. Two types of motion have been observed for the methylene chain of [8]metacyclophane 4c, flipping and pseudorotation.
Darstellung von dreikernigen Carbonylmanganaten sowie deren Reaktionsprodukten mit InCl3; Röntgenstrukturanalysen von K3[Mn3(μ‐CO)2(CO)10], [(C6H5)4As]2[(μ‐H)Mn3(μ‐CO)10], [{(C6H5)3P}2N]2[μ‐H)Mn3(CO)12], [(C6H5)4As]2[{μ‐H)Mn3(CO)12}2(μ4‐In)] und [(C6H5)4As]2[{(μ‐H)Mn3(CO)12}(μ3‐In){Mn(CO)5}Cl]
Authors: Schatz Wolfgang , Neumann Hans‐Peter , Nuber Bernhard , Ziegler Manfred L. , Kanellakopulos Basil 
Published: July 2007

Synthesis of Trinuclear Carbonylmanganates and Their Reaction Products with InCl3; X‐ray Structure Determinations of K3[Mn3(μ‐CO)2(CO)10], [(C6H5)4As]2[(μ‐H)Mn3(μ‐CO)10], [{(C6H5)3P}2N]2[μ‐H)Mn3(CO)12], [(C6H5)4As]2[{μ‐H)Mn3(CO)12}2(μ4‐In)] und [(C6H5)4As]2[{(μ‐H)Mn3(CO)12}(μ3‐In){Mn(CO)5}Cl]Mn2(CO)10 reacts with KOH in aqueous solution to give the potassium carbonylmanganate K3[Mn3(μ‐CO)2(CO)10] (1). The trianion 1 is isoelectronic with Fe3(CO)12 and is protonated with methanol to form the μ‐hydrido cluster [(μ‐H)Mn3;‐(CO)12]3⊖, which is precipitated with [{(C6H5)3P}2N]Cl as [{(C6H5)3P}2N]2[(μ‐H)Mn3(CO)12] (2), whereas the carbonyl‐bridged μ‐hydrido species [(μ‐H)Mn3(μ‐CO)2(CO)10]2⊖ seems to be trapped as the [(C6H5)4As]⊕ salt 3. The reaction of 3 with InCl3 yields the Mn‐In clusters [(C6H5)4As]2[{(μ‐H)Mn3(CO)12}2;‐(μ4‐In) (4) and [(C6H5)4As]2[{(μ‐H)Mn3(CO)12}(μ3‐In){Mn(CO)5}Cl] (5). X‐ray structure analyses have been carried out for the compounds 1 – 5.
Synthese und Reaktionen von Eisen‐Clustern mit μ3;‐λ2‐koordiniertem Trifluormethylisocyanid‐Liganden. Bildung eines N;‐(Trifluormethyl)‐formimidoyl‐Liganden
Authors: Lentz Dieter , Marschall Robert 
Published: July 2007

Syntheses and Reactions of Iron Cluster Compounds with a μ3;‐λ2‐Coordinated Trifluoromethyl Isocyanide Ligand. Formation of an N;‐(Trifluoromethylformimidoyl LigandPyrolysis of the iron clusters Fe3(CO)10(L)(μ2‐CNCF3) (1a – d) [LP(OCH3)3 a, P(OC2H5)3 b, P(CH3)3 c, P(C2H5)3 d] in n‐heptane at 95°C results in the reversible elimination of two mol of carbon monoxide and formation of the cluster compounds Fe3(CO)8(μ3;‐λ2‐CNCF3)L (2a–d). According to the crystal structure determination of 2a trifluoromethyl isocyanide acts as a μ3;‐λ2‐bridging ligand with its CN bond perpendicular to one iron‐iron edge. 2a reacts with molecular hydrogen to yield Fe3(CO)8(L)(μ3;‐λ2‐HCNCF3)(μ2‐H) (3a) containing a μ3;‐λ2;‐N;‐(trifluoromethyl)formimidoyl ligand. 3a exists as a mixture of three isomers. The isomerization of two of these isomers is studied by variable temperature 1H‐, 19F‐, and 31P‐NMR spectroscopy. Reaction of 2a with NaBH4 leads to the ionic cluster Na[Fe3(CO)8(L)(μ3;‐λ2‐HCNCF3)] (4a), which yields 3a on protonation with trifluoroacetic acid.
Steuerung der Aggregation von Mangankomplexen durch unterschiedliche Basen an den Beispielen [Mn(O2CCF3)2(py)4] und [Mn3(O2CCF3)6(benz)6]
Authors: Hübner Kay , Roesky Herbert W. , Noltemeyer Mathias , Bohra Rakesh 
Published: July 2007

Influencing the Aggregation of Manganese Complexes by Different Bases: Formation of [Mn(O2CCF3)2(py)4] and [Mn3(O2CCF3)6(benz)6]Manganese powder reacts quantitatively with trifluoroacetic acid to yield Mn(O2CCF3)2 (1). The aggregation of 1 is directed by different N‐containing bases. Pyridine (py) forms the mono‐nuclear complex [Mn(O2CCF3)2(py)4] (2), while benzonitrile (benz) yields the trinuclear complex [Mn3(O2CCF3)6(benz)6] (3). The X‐ray structures of 2 and 3 are described.
Synthesen neuer Azofarbstoffe mit 1,6‐Methano[10]annulen‐Partialstruktur
Authors: Neidlein Richard , Lu Yinrong 
Published: July 2007

Synthesis of New Azo Dyes with 1,6‐Methano[10]annulene Partial StructureBridged quinone hydrazones 1 are transformed by aromatic acyl chlorides to the corresponding azo dyes 3a –6. Nitro derivative 1a reacts analogously with p‐tolylsulfonyl chloride, acetyl chloride, methyl chlorocarbonate, and dimethylcarbamoyl chloride to give the corresponding azo dyes 7 and 8a –c. Reaction of 1a with diphenylcarbamoyl chloride unexpectedly leads to Berson‐Wilcott rearrangement with formation of the azo dye 9. Acylations of 1a with the bifunctional acyl chlorides diphosgene and terephthaloyl chloride yield the azo derivatives 11 and 12.
The Conformational Behaviour of 10‐Substituted Spiro[4.5]decanes
Authors: Jens Wolff J. , Frenking Gernot , Harms Klaus 
Published: July 2007

AbstractThe conformational behaviour of 10‐X‐substituted 1,4‐dioxa‐and 1,4,6‐trioxaspiro[4.5]decanes 1 – 4 has been studied by 13C‐, 19F‐ and 1H‐NMR spectroscopy. Two X‐ray analyses (of 2a,e) are presented, and their implications to cleavage reactions of chiral acetals are discussed. Participation of twist boat forms in the conformeric equilibrium of at least 1c has been made plausible by observing 13C,19F‐NMR coupling constants. The ratios of axial to equatorial conformer in 1 – 4 have been calculated by molecular mechanics.
Synthese von 1,2,5‐Azastannaborol‐Derivaten aus Schwefeldiimid‐Anionen und cis‐Stannyl‐boryl‐alkenen – Röntgenstrukturanalyse von zwei 2,5‐Dihydro‐1‐(imino‐λ4‐sulfanyliden)‐1,2,5‐azastannaboratolen
Authors: Wrackmeyer Bernd , Frank Stefan M. , Herberhold Max , Borrmann Horst , Simon Arndt 
Published: July 2007

Synthesis of 1,2,5‐Azastannaborole Derivatives from Sulfur Diimide Anions and cis‐Stannyl‐boryl‐alkenes – X‐ray Crystallographic Study of Two 2,5‐Dihydro‐1‐(imino‐λ4‐sulfanylidene)‐1,2,5‐azastannaboratoles(E)‐3‐(Diethylboryl)‐2‐(chlorodimethylstannyl)‐2‐pentene (1) reacts with the sulfur diimide anions 3 [R – NSN−K+, R=tBu (a), Me3Si (b), tBu2P (c)] in a 1:1 ratio, and with 4 (K+;−NSN−K+) in a 2:1 ratio, to give various heterocycles. The first products of the reaction between 1 and 3 [2,5‐dihydro‐1‐(imino‐λ4‐sulfanylidene)‐1,2,5‐azastannaboratoles 5a, b, c] are isolated at −30°C and characterized by X‐ray crystallography. The compounds 5a,b rearrange into the borole derivates 6a,b (with an additional NSn coordination) by transfer of an ethyl group from the boron to the sulfur atom. Ethylene is eliminated from compound 6a (not 6b) to give the diaminosulfane derivative 7a. The 2:1 reaction between 1 and 4 affords an unstable intermediate 8 with a fluxional structure, leading to 9 in which an EtS moiety bridges a borole ring (analogous to 6 but without the additional N – Sn coordination) and a boratole ring (analogous to 5). All compounds are characterized by 1H‐, 11B‐, 13C‐, 15N‐ (in part), 29Si‐ and 119Sn‐NMR spectra.
Small and Medium Rings, 76. Photorearrangement of Polycyclic Quinoxalines, Isomerisations of Isodrin‐Type and Aza‐Di‐π‐Methane Chromophores
Authors: Behr Jürgen , Braun Ralf , Martin Hans‐Dieter , Steigel Alois , Rubin Mordecai B. 
Published: July 2007

AbstractThe multichromophoric polycyclic quinoxaline 11 has been synthesized starting with diketone 7. Irrespective of whether quinoxaline 11 is irradiated in its nπ☆ or ππ☆ band, the photoproduct formed in high yield is invariably the cage compound 14. This excitation energy transfer from the quinoxaline to the isodrin subchromophore of 11 is facilitated by a strong mixing of energy levels in these two fragments of 11, as evidenced by the PE spectrum of quinoxaline 13. The direct interaction of a quinoxaline chromophore with a nonconjugated double bond, i.e. an aza‐di‐π‐methane rearrangement, is shown to occur photochemically in bicyclic quinoxaline 12.
Adamantan als Baustein neuer Araliphane Synthese, Spektroskopie und Kristallstrukturen
Authors: Dohm Joachim , Vögtle Fritz , Nieger Martin , Rissanen Kari 
Published: July 2007

Adamantane as a Building Block of New Araliphanes – Synthesis, Spectroscopy, and Crystal StructuresExchange of benzene units for aliphatic building blocks in cyclophanes leads to new molecules of the “araliphane” type. With adamantane the araliphanes 2 – 4 are synthesized. Their stereochemical behavior as shown by NMR studies and X‐ray crystallographic analyses differs significantly from that of their aromatic counterparts. The signals of the intraannular adamantane hydrogens are strongly shifted upfield up to δ=– 2.18 (in 2). 4 is obtained as a racemic mixture of enantiomers (in the crystalline state) and shows a boat‐like deformation of the benzene moiety.
Synthese mittlerer und großer Ringe, XXVIII. Die Rutheniumtetroxid‐Oxidation von 3,6‐Alkano‐4,5‐oligomethylenoxepinen Ein neuer Weg zu makrocyclischen Di‐, Tri‐ und Tetraketonen
Authors: Tochtermann Werner , Dibbern Regine , Haase Margret , Bruhn Thomas , Wolff Christian 
Published: July 2007

Synthesis of Medium and Large Rings, XXVIII. – The Ruthenium Tetroxide Oxidation of 3,6‐Alkano‐4,5‐oligomethyleneoxepines – A New Approach to Macrocyclic Di‐, Tri‐, and TetraketonesThe oxepines 3, 7, and 9 are oxidized by means of ruthenium tetroxide to give various types of macrocyclic ketones such as 4, 8 and 10. The diketones 12 can be synthesized by ether cleavage of 9a to give 11a and subsequent oxidation of 11b and 11d to the monocyclic compounds 12a and 12b.
Sterische Behinderung der Isocyanid‐Cyanid‐Umlagerung in einer Brückenkopfposition
Authors: Pakusch Joachim , Rüchardt Christoph 
Published: July 2007

Steric Hindrance of the Isocyanide‐Cyanide Rearrangement in a Bridgehead PositionThe activation barrier of the isocyanide‐cyanide rearrangement of 13‐isocyano‐1,4,5,8,9,12‐hexamethyltriptycene (5) is the highest of all known isocyanides. The special position of this compound can be explained by a strong increase of strain enthalpy during the isomerization. This is due to the cage‐like inclusion of the isocyano group in the bridgehead position by the methyl groups in the positions 1, 8, and 9.
Tris(diethylamino)cyclotriboran sowie Konstitutionsisomerie zwischen cyclo;‐ und closo‐Hexakis(diethylamino)hexaboran(6)
Authors: Baudler Marianne , Rockstein Konrad , Oehlert Wolfgang 
Published: July 2007

Tris(diethylamino)cyclotriborane and Constitutional Isomerism Between cyclo;‐ and closo‐Hexakis(diethylamino)hexaborane(6)The reaction of Et2NBCl2 with potassium in boiling cyclohexane provides a mixture of aminopolyboranes, containing 20–25 mol‐% (BNEt2)3 (1), (BNEt2)4 (2), and cyclo;‐(BNEt2)6 (3), respectively, as well as varying amounts of closo;‐(BNEt2)6 (4). Whereas 1 and 3 have been highly enriched by means of HPLC, 4 has been isolated by column chromatography and crystallization. On standing in solution at room temperature, the cyclo‐isomer 3 slowly rearranges to the closo‐isomer 4, while at elevated temperatures the reverse conversion occurs. Hence 4, which is the first neutral B6 compound with octahedral structure, has a relatively higher thermodynamic stability at normal conditions.
Substituenteneffekte auf die CC‐Bindungsstärke, 10. Resonanzstabilisierung von Alkylradikalen durch zwei geminale Cyangruppen
Authors: Pakusch Joachim , Beckhaus Hans‐Dieter , Rüchardt Christoph 
Published: July 2007

Effects of Substituents on the Strength of C–C Bonds, 10. – Resonance Stabilization of Alkyl Radicals by Two Geminal Cyano GroupsThe activation parameters of the homolytic cleavage of the Cq – Cq bonds of several dialkylated malonodinitriles (2–5) and of 1,1,2,2‐tetracyanoethane (7) and the heat of dissociation of 6 in solution have been determined. Together with the ground state strain of the radical precursors (obtained from the heats of combustion or EFF calculations) the steric influence on the dissociation process has been determined. The resonance stabilization energy of α,α'‐dicyanoalkyl radicals then calculated was (12.4 ± 0.9) kcal/mol. This result is discussed within the concept of capto‐dative stabilization. The destabilizing interaction of two geminal cyano groups is apparently the same in the ground state of 2 – 7 and the radicals generated from them.
Chiral Organometallic Reagents, I Stereoselective Exchange of Diastereotopic Bromine Atoms by Lithium in 1,1‐Dibromo‐3‐(trimethylsilyloxy)alkanes
Authors: Hoffmann Reinhard W. , Bewersdorf Martin , Kr üger Michael , Mikolaiski Wolfgang , St ürmer Rainer 
Published: July 2007

AbstractBromine‐lithium exchange in 1,1‐dibromo‐3‐(trimethylsilyl‐oxy)alkanes 4 and 6 affords the carbenoids 8 and 14, which have been added to ketones, aldehydes, arylboronates, and silylating agents. Diastereoselectivity in the generation and trapping of the carbenoids ranged between 70 – 90% for 8 and >90% for 14.
Chiral Organometallic Reagents, II. Equilibration of Diastereomeric Carbenoids, the tert‐Butyl 2‐Bromo‐2‐lithio‐1‐methylcyclopropanecarboxylates
Authors: Schmidt Armin , Köbrich Gert , Hoffmann Reinhard W. 
Published: July 2007

AbstractThe diastereomeric carbenoids 6 are generated at ‐125°C from the dibromocyclopropane 5 by halogen‐metal exchange and trapped by electrophiles. Since the resulting carbenoids 6 equilibrated by halogen‐metal exchange with their precursor dibromo compound 5, the product ratios depend strongly on the reaction conditions used. Normal addition of n‐butyllithium favors equilibration giving “thermodynamic ratios” of the carbenoids. Inverse addition of 5 to tert‐butyllithium approaches the “kinetic ratio” of carbenoids, which is revealed in reactions in which the carbenoids are trapped in situ by alcohols. The carbenoids 6 have been found to be configurationally stable at ‐125°C. They undergo rapid equilibration at temperatures above ‐78°C before decomposition sets in at ‐60°C.
Gas‐Phase Thermolysis, 14. On the Isomerization of Dimethyl Carbonate and Its Mono‐, Di‐, and Trithio Analogs
Authors: Egsgaard Helge , Carlsen Lars , Sülzle Detlev , Schwarz Helmut 
Published: July 2007

AbstractGas‐phase pyrolysis of dimethyl carbonate and its mono‐, di‐, and trithio analogs has been performed in the temperature range from 1253 to 1404 K applying the gas phase Curie‐point pyrolysis technique. Real‐time analyses have been carried out by means of mass‐spectrometric techniques. The possible isomerizations of the ester functions have been studied by collisional activation mass spectrometry in combination with appropriate D, 18O, and 34S labeling. It is demonstrated that methyl group migrations can be induced pyrolytically in cases where oxygen‐to‐oxygen or oxygen‐to‐sulfur isomerizations are involved; in contrast, sulfur‐to‐oxygen as well as sulfur‐to‐sulfur isomerizations apparently do not take place.
Die Synthese von Chlor(trichlormethyl)sulfin, Cl3C(Cl)CSO
Authors: Maletzo Christian , Sundermeyer Wolfgang 
Published: July 2007

Synthesis of Chloro(trichloromethyl)sulfine, Cl3C(Cl)CSOThe unstable trichlorothioacetyl chloride (2) could be trapped by a Diels‐Alder reaction with anthracene to form the adduct 3, which in turn could be oxidized to the corresponding sulfine adduct 4. Finnaly, chloro(trichloromethyl)sulfine (5) was prepared in good yield by vacuum thermolysis (retro Diels‐Alder reaction) of 4.
Komplexierung von 1,3‐Dihydro‐1,3‐diborapentafulven‐Derivaten mit Fe(CO)3‐Fragmenten: Synthesen, Kristall‐ und Elektronenstruktur von μ‐(η4:η5‐1,3‐Dihydro‐1,3‐diborapentafulven)‐bis (tricarbonyleisen)‐Komplexen
Authors: Feßenbecker Achim , Enders Markus , Pritzkow Hans , Siebert Walter , Hyla‐Kryspin Isabella , Gleiter Rolf 
Published: July 2007

Complexation of 1,3‐Dihydro‐1,3‐diborapentafulvene Derivatives with Fe(CO)3 Fragments: Syntheses, Crystal and Electronic Structure of μ‐(η4: η5‐1,3‐Dihydro‐1,3‐diborapentafulvene)‐bis(tricarbonyliron) ComplexesReactions of the 1,3‐diborapentafulvene derivatives 1a–c with (CO)3Fe(C8H14)2 lead to the violet dinuclear complexes 3a–c, which possess a slipped triple‐decker structure. The X‐ray structure analyses of 3b,c reveal that one Fe(CO)3 group is pentahapto‐coordinated to the 1,3‐diborole frame of C2B2C=C, whereas the other interacts with the Y‐shaped B2C=C unit. The latter resembles the interaction of Fe(CO)3 with trimethylenemethane. An MO calculation indicates that the formation of 3 occurs by distortion of 1 · Fe(CO)3; the slippage of Fe(CO)3 from η5 to η4 bonding is followed by η5 coordination of the second Fe(CO)3 group.
Untersuchung zum Reaktionsverhalten von Nitrilen RCN gegenüber [I3]+[AsF6]− (R = CH3, CF3, Br, I, H)
Authors: Tornieporth‐Oetting Inis , Klapötke Thomas 
Published: July 2007

Investigation on the Reactivity of Nitriles RCN towards [I3]+[AsF6]− (R = CH3, CF3, Br, I, H)The reaction behaviour of cyanogen compounds R — CN (R = CH3, CF3, Br, I, H) towards [I3]+[AsF6]− is investigated. Whereas CF3CN and BrCN do not react, acetonitrile and cyanogen iodide react with the [I3]+ cation to yield the linear species [ICNI]+ and [CH3CNI]+. The different reactivity of RCN towards [I3]+ is discussed on the basis of the substituent electronegativity X(R) and the HSAB principle. Simple thermodynamic estimations (Born‐Haber cycle) explain the greater stability of the (acetonitrile)iodonium cation compared with the inorganic (iodocyan)iodonium salt.
Optische Aktivität und absolute Konfiguration von 1,4‐Dihydroxytricyclo[6.4.0.04,9]dodecan‐7,10‐dion und ‐7‐on
Authors: Jürgensen Micael , Roßnagel Ingrid , Musso Hans 
Published: July 2007

Optical Activity and Absolute Configuration of 1,4‐Dihydroxytricyclo[6.4.0.04,9]dodecane‐7,10‐dione and ‐7‐one(±)‐1,4‐Dihydroxytricyclo[6.4.0.04,9]dodecane‐7,10‐dione (1) has been resolved into the pure enantiomers through chromatographic separation of the diastereomeric dithioacetals 3A and 3B prepared with (‐)‐(2R,3R)‐2,3‐butanedithiol (2). The dithioacetals were converted into the acetals 4, from which the monoketones 6 were obtained by Raney nickel desulfurization/deprotection. The absolute configuration of (1R,4S,8S,9S)‐(‐)‐6 is correlated with that of (1R,4S,8S,9S)‐(‐)‐ 1 by means of Cotton effects and its chromatographic behavior on potato starch. Some interaction between the carbonyl groups in the diketone 1 is demonstrated by comparison of UV, CD, and PE spectra with those of the monoketone 6.
Asymmetrische Synthese chiraler Phosphorverbindungen durch destruktiv‐Oxidation von P(III)‐Verbindungen mittels chiraler Oxaziridine
Authors: Verfürth Uwe , Ugi Ivar 
Published: July 2007

Asymmetric Synthesis of Chiral Phosphorus Compounds by Destructive‐Selective Oxidation of P(III) Compounds by Means of Chiral OxaziridinesFrom camphor and fenchone chiral N ‐sulfonyloxaziridines (e.g, 7,13) are available that are well‐suited for the destructive‐stereoselective oxidation of P(III) compounds 16. Optimum reagents and reaction conditions for this oxidation are determined by a systematic study. Chiral P(III) and P(V) compounds can thus be prepared from racemic P(III) derivatives.
Zur Alkylierung von 1,3‐Dithietan‐1,1,3,3‐tetroxid (Disulfen) mit Nonafluorbutansulfonsäureestern
Authors: Frasch Markus , Sundermeyer Wolfgang , Waldi Joachim 
Published: July 2007

Alkylation of 1,3‐Dithietane 1,1,3,3‐Tetroxide (Disulfene) by NonafluorobutanesulfonatesSilyl and alkyl esters of nonafluorobutanesulfonic aicd are extremely powerful substitution reagents for disulfenes. Starting from trans‐2,4‐trimethylsilyldisulfene (1) and methyl nonafluorobutanesulfonate (11), 2,4‐dimethyl‐2,4‐bis(trimethylsilyl)‐1,3‐dithietane 1,1,3,3‐tetroxide (2) is prepared. 2 is hydrolyzed to 2,4‐dimethyl‐1,3‐dithietane 1,1,3,3‐tetroxide (3). Rapid H/D exchange reaction of 3 with D2O leads to 4. Compound 3 is deprotonated by aqueous potassium hydroxide and a potassium salt is obtained, the structure of which is most probably 5a. 2,2,4,4‐Tetramethyl‐1,3‐dithietane 1,1,3,3‐tetroxide (7) is obtained from 5 and methyl iodide, i.e. the ring system remains intact, whereas hydrolysis furnishes the ring‐opened product 6. — Three new routes for the synthesis of methyl nonafluorobutanesulfonate (11) via the silver salt 9 or dimethyl sulfate (96% yield) or nonafluorobutanesulfonic anhydride (10) are described.