bluuebunny/crossref_metadata_2025_split huggingface dataset:
SET‐Mechanismus bei Substitutionsreaktionen an Diorganyldichalkogeniden
Authors: Bildstein Benno , Giselbrecht Karlheinz , Sladky Fritz 
Published: July 2007

SET Mechanism in Substitution Reactions with Diorganyl DichalcogenidesReaction of the sterically demanding tris(trimethylsilyl)methyl carbanion (Tsi⊖) with bis[tris(trimethylsilyl)methyl] diselenide (Tsi2Se2) or ditelluride (Tsi2Te2) in THF does not lead to the expected substitution products Tsi2Se or Tsi2Te. Instead, 2‐ tetrahydrofuranyl tris(trimethylsilyl)methyl selenide (4a) or telluride (4b), tris(trimethylsilyl)methane (5), and tris(trimethylsilyl)‐methylselenol (6a) are formed. This is interpreted in terms of a single electron transfer (SET) from Tsi⊖ to the respective diorganyl dichalcogenide, giving rise to intermediate chalcogenyl radicals TsiSe⊙ and TsiTe⊙, which are trapped by the solvent THF. Methyl‐ or phenyllithium react with Tsi2Se2 or Tsi2Te2 to afford the expected substitution products MeChTsi (1a,1b) or PhChTsi (2a, 2b) (a: CH  Se, b: Ch  Te), but Products derived from chalcogenyl radicals are detectable in minor yields.
Der Einfluß von Substituenten auf die Photochromie Dihydroazulen ⇄ Dicyanvinylheptafulven: Sterische und elektronische Effekte bei 9‐Anthrylverbindungen — Synthese von kondensierten Hydropentalenen
Authors: Gierisch Sebastian , Bauer Walter , Burgemeister Thomas , Daub Jörg 
Published: July 2007

AbstractDie Synthese von 2‐(9‐Anthryl)‐1,8a‐dihydro‐1,1‐azulendicarbonitril (1a) über das Tetrahydroazulen 5a, ausgehend von 8‐Methoxyheptafulven (3) durch [8 + 2]‐Cycloaddition, wird beschrieben. Durch Bestrahlung mit sichtbarem Licht wird 1a in das Vinylheptafulven 2a umgelagert. Dieses wiederum kann unter thermischen Bedingungen in 1a zurückverwandelt werden. Die sterische Hinderung 9‐anthrylsubstituierter Verbindungen beeinflußt die Geschwindigkeit der [8 + 2]‐Cycloaddition sowie die Kinetik der thermischen Rückreaktion 2a → 1a und verleiht dem Dihydroazulen 1a zudem thermochrome Eigenschaften. Aus 5a entsteht durch intramolekulare elektrophile Substitution das kondensierte Hydropentalen 9, das durch Oxidation in den kondensierten Polycyclus 11 umgewandelt wird. Die stereochemischen Eigenschaften der 9‐Anthrylverbindungen werden durch ein‐ und zweidimensionale 1H‐NMR‐Spektroskopie ermittelt.
Reaktionen mit Aziridinen, 52: Tryptamin‐Verbindungen mit Seitenkettensubstitution aus Indolyllithium und aktivierten Aziridinen
Authors: Onistschenko Andreas , Stamm Helmut 
Published: July 2007

Reactions with Aziridines, 52. — branched‐Chain Tryptamine Compounds from Indolyllithium and Activated AziridinesReaction of indolyllithium 1 with activated aziridines 2 in toluene provides the tryptamines 3 or 4 in good yields.
Hetero‐π‐Systeme, 17: Aminosilylen (Aminosilandiyl)
Authors: Maier Günther , Glatthaar Jörg , Reisenauer Hans Peter 
Published: July 2007

Hetero π‐Systems, 17. — Aminosilylen (Aminosilanediyl)Aminosilylene can be prepared by 254‐nm photolysis of silyl azide isolated in an argon matrix at 12 K. Subsequent irradiation with wavelengths > 300 nm yields silaisonitrile (3) and molecular hydrogen. This reaction may be reversed with 254‐nm light.
Chrom‐Komplexe mit cyclo‐Asx‐Liganden
Authors: Scherer Otto J. , Wiedemann Wolfgang , Wolmershäuser Gotthelf 
Published: July 2007

Chromium Complexes with cyclo‐Asx, LigandsThe interaction of [(η5C5Me4R)(CO)2Cr]2(Cr≡Cr) (1a: R = CH3 1b: R = C2H5) with yellow arsenic (As4) affords the triarsachromatetrahedranes [(η5‐C5Me4R)(CO)2Cr(η3‐As3)] (2a, b) as well as the 27‐VE triple‐decker complexes [{(η5‐C5Me4R)Cr}2‐(μ,η5‐As5)] (3a, b) 3 is also formed photochemically from 2. 2a and 3b have been characterized by X‐ray structure analyses. The cyclo‐As5 ligand forms a regular arsenic pentagon.
Regio‐ und stereoselektive Photocycloadditionen aromatischer Aldehyde an Furan und 2,3‐Dihydrofuran
Authors: Griesbeck Axel G. , Stadtmüller Stefan 
Published: July 2007

Regio‐ and Stereoselective Photocycloaddition Reactions of Aromatic Aldehydes to Furan and 2.3‐DihydrofuranThe Paterno‐Büchi reaction between benzaldehyde (1a), tolualdehyde (1b), mesitylaldehyde (1c), and 2,4‐di‐tert‐butyl‐4‐methylbenzaldehyde (1d) and the electron‐rich alkenes furan and 2,3‐dihydrofuran has been investigated. The reaction with furan leads exclusively to exo‐6‐aryl‐2,7‐dioxabicyclo[3.2.0]‐hept‐3‐enes 2a to 2d in yields of 78% to 97% (2a, 2b). In the photoreaction of 2a and 2b with 2,3‐dihydrofuran, however, mixtures of exo‐ and endo‐7‐aryl‐2,6‐dioxabicyclo[3.2.0]heptanes 3a and 4a (7:1) as well as 3b and 4b (15:1) could be isolated. The sterically more hindered aldehydes 1c and 1d give rise to exclusive formation of the endo adducts 3c and 3d. Irradiation of 1d in the presence of 2,3‐dihydrofuran leads to the benzocyclobutenol 5 (Norrish‐type II; up to 45%) as a side product. The regioselectivity observed in these reactions may be explained by comparing the stability of the possible 1,4‐diradical intermediates. The observed stereoselectivity could be rationalized by the geometry of the triplet 1,4‐diradicals during the ISC process and by the life times of the resulting singlet 1,4‐diradicals.
Silicium‐Verbindungen mit starken intramolekularen sterischen Wechselwirkungen, 391) Ein spirocyclisches Silan aus einem 2,2‐Dimesityldisilan
Authors: Weidenbruch Manfred , Pan Youlin , Peters Karl , Schnering Hans Georg Von 
Published: July 2007

Silicon Compounds with Strong Intramolecular Steric Interactions, 39. – A Spirocyclic Silane from a 2.2‐DimesityldisilaneTreatment of 1,1‐Di‐tert‐butyl‐1,2‐dichloro‐2,2‐dimesityldisilane (3) with lithium tert‐butylamide gives the spirocyclic silane 5 by a twofold intramolecular ring formation reaction. The X‐ray structure analysis of 5 reveals strong deviations from the idealized tetrahedral geometry at the spirocyclic silicon atom.
Pentamakrocyclische Tris‐Kronen. – Selektive Bindung von Kationen, Anionen und Neutralverbindungen
Authors: Wallon Alexander , Werner Ute , Müller Walter M. , Vögtle Fritz , Nieger Martin 
Published: July 2007

Pentamacrocyclic Tris‐Crown Hosts. – Selective Binding of Cationic, Anionic, and Neutral Guest CompoundsThe tris‐crown host compounds 1–4 were synthesized for the first time. The X‐ray crystal structures of 2 and of the 1:3 complex of 1 and KSCN were determined. Whereas in the free crown 2 a less well preorganized molecular cavity is encountered, in the complex of 1 with KSCN one potassium ion is bound to each crown ether unit. One of the three SCN− anions is situated in the interior of the cavity and in addition is disordered in such a way as to be bound to the K+ using partially the S atom of the SCN− ion. Organic guest molecules like 1,2‐, 1,3‐, 1,5‐, 2,6‐, and 2,7‐naphthalenediol as well as β‐naphthol in acidic water solution are bound selectively in the interior of the cavities of the host molecules 2 and 3, but not by 1 and 4, the cavities of which seem to be too small and too large, respectively. In contrast, the binding of α‐naphthol and of smaller phenolic guest molecules like phenol, resorcinol, pyrocatechol, phloroglucinol, pyrogallol, and 1,2,4‐trihydroxy‐benzene with the host 1–4 is much less pronounced (1H‐ NMR highfield shifts).
Beiträge zur Chemie der Halogensilan‐Addukte, 20. Hexakoordinierte Verbindungen von Trichlorsilanen. – Darstellung, Kristall‐und Molekülstruktur von RSiCl3·bipy
Authors: Kummer Dieter , Chaudhry Subhash C. , Debaerdemaeker Tony , Thewalt Ulrich 
Published: July 2007

Hexacoordinated Compounds of Trichlorosilanes. – Preparation, Crystal and Molecular Structure of BSiCl3·bipyThe octahedral Si complexes CHCl2SiCl3·bipy (1), CCl3SiCl3·bipy (2), and Cl3SiCCl2SiCl3·bipy (3) are obtained by the reaction of the respective trichlorosilanes and 2.2′‐bipyridine (bipy). Their composition is independent of the initial ratio of the components. X‐ray structure determinations show the Si atoms of all three complexes to be octahedrally coordinated with the substituted methyl groups in axial positions. The configurations represent structures of least steric hindrance assuming spheric substituents and demonstrate the usefulness of this structural model for solid compounds (in contrast possibly to dissolved compounds) even for substitutents deviating strongly from this assumption. Bond lengths and angles agree with the presence of hexacoordinated complexes. Deviations from expected values are interpreted in terms of considerable steric interactions. 3 represents a case of strongly hindered coordination requiring interesting steric adjustments.
Lineare Oligophosphaalkane, XXV. Synthese von Ph2PCH2PH2 und (ph2PCH2)2PH durch Phosphinomethylierung von PH3 unter Phasentransferkatalyse
Authors: Langhans Klaus‐Peter , Stelzer Othmar , Weferling Norbert 
Published: July 2007

Linear Oligophosphaalkanes, XXV1. – Synthesis of Ph2PCH2PH2 and (Ph2PCH2)2PH by Phosphinomethylation of PH3 with Phase‐Transfer CatalysisAlkylation of Ph2PH with CH2Cl2 under phase‐transfer conditions in the system dichloromethane/toluene/water affords Ph2P‐CH2Cl in high yields. Depending on the reaction conditions employed Ph2P‐CH2Cl reacts with PH3 in the two phase system under phase‐transfer catalysis (nBu4NCl) to yield the tertiary‐primary methylenebis(phosphane) Ph2P‐CH2‐Ph2 (2) or the PH functional triphosphaalkane Ph2P‐CH2‐PH‐CH2‐PPh2 (3), respectively. Metallation of 2 and 3 with RLi (R = nBu, tBu) and subsequent reaction with Me3siCl yields the silyl derivatives 2e and 3b, respectively. The analysis of the 1H‐ 13C‐ and 31P‐NMR spectra is reported.
Reaktive EC(p‐p)π‐Systeme, XXIII. Unerwartete Isomerisierung des Perfluorisopropylidenphosphans F3CPC(CF3)2 zum Perfluorisopropenylphosphan F3CPF(F3C)CCF2
Authors: Grobe Joseph , Van Due Le 
Published: July 2007

Reactive E = C(p‐p)x‐Systems, XXIII. – Unexpected Isomerization of Perfluoroisopropylidenephosphane F3CP = C(CF3)2 to the Perfluoroisopropenylphosphane F3CPF(F3C)C = CF3Elimination of Me3SnF from the stannylphosphane Me3Sn(F3C)PCF(CF3)2 (2) by gas‐phase pyrolysis at 220°C surprisingly yields the isopropenyl phosphane F3CPFC(CF3)=CF2 (5) instead of the expected isopropylidene derivative F3CP=C(CF3)2 (4). In a similar manner, HF elimination from the phosphane HP(CF3)CF(CF3)2 (3) by passing its vapour over KOH pellets leads to 5. The formation of 5 is due to a spontaneous isomerization of the labile intermediate 4.
π‐Complexes of p‐Block Elements: Synthesis and Structures of Adducts of Arsenic and Antimony Halides with Alkylated Benzenes
Authors: Schmidbaur Hubert , Nowak Reinhold , Steigelmann Oliver , Müller Gerhard 
Published: July 2007

Abstract1,2,4,5‐Tetramethyl‐and pentamethylbenzene from stable 1:2 complexes with SbCl3 of the type (C6H6‐Men) · 2SbCl3(1,2) with an inverse sandwich structure. The compounds crystallize isotypically and are isostructural to the (hexamethylbenzene)antimony and ‐bismuth complexes.They are thus built of tetrameric chlorine‐bridged Sb4Cl12 units, which are crosslinked at the metal centers with four other tetramers by double‐sided arene coordination (X‐ray structure analysis of 1). The Sb atoms, which are in a distorted trigonal bipyramidal environment, show a slight deviation from a centric (η6) coordination. The same stoichiometry and the same structural principle are found for the complex (C6Me6 · 2 AsCl3 (4), which is obtained from solutions of hexamethylbenzene and AsCl3 in toluene. In 4 the arsenic atoms are η6‐coordinated to the hexamethylbenzene ring from both sides (X‐ray analysis). Treatment of AsBr3 with hexamethylbenzene leads to a product of the composition 5 (C6Me6) · AsBr3. Reaction of hexaethylbenzene with AsCl3 in petroleum ether leads to the formation of the 1:2 complex (C6Et6) · 2 AsCl3 (5), built of discrete inverse sandwich units, which are arranged in strings parallel to the crystallographic c axis. From solutions of AsCl3 (AsBr3), SbCl3 (SbBr3) and hexaethylbenzene in petroleum ether ternary compounds are isolated with an As:Sb ratio of 1:5.2 and 1:1.86, respectively. Single crystal X‐ray structure determinations failed as a consequence of severe disorder.
Zur Lewis‐Acidität von Nickel(0), XII. Dimethylaluminiumhydrid‐Komplexe von Nickel(0)
Authors: Pörschke Klaus‐Richard , Kleimann Wolfgang , Tsay Yi‐Hung , Krüger Carl , Wilke Günther 
Published: July 2007

On the Lewis Acidity of Nickel(0). XII. ‐ Dimethylaluminium Hydride Complexes of Nickel(O)Ni(CDT) reacts with (1‐azabicyclo[2.2.2]octane)dimethylaluminium hydride in pentane to form the yellow crystaline addition compound (C7H13N)(Me2AlH)Ni(CDT) (2c). In its crystal structure 2c exhibits a Ni–H–Al three‐center bond. Displacement of the CDT ligand of 2c with ethene in pentane at 0°C yields light brown crystals of (C sb7H13N)(Me2AlH)Ni(C2H4)2 (4), which is also obtained from Ni(C2H4)3 and (C7H13N)‐Me2AlH). Complex 4 is converted by CO at – 78°C into the colorless carbonyl complex (C7H13N)(Me2AlH)Ni(CO)3 (5). 2c and 4 may be considered as model compounds for intermediates of the nickel(0)‐catalyzed hydroalumination reaction of alkenes.
Organometallic Compounds of the Lanthanides, 57. Pyrrolyl Complexes of Yttrium and Lutetium. Molecular Structure of Dicyclopentadienyl(2,5‐dimethylpyrrolyl)(tetrahydrofuran)lutetium(III)
Authors: Schumann Herbert , Lee Pil Ryul , Dietrich Andreas 
Published: July 2007

AbstractThe reactions of Na(NC4H4) with (C5H5)2LuCl(THF) and (C5Me5)2YCl(THF) result in the formation of the pyrrolyl complexes (C5H5)2Lu(NC4H4) (1) and (C5Me5)2Y(NC4H4)(THF) (2), respectively. Na(NC4H2Me2) reacts with (C5H5)2LuCl(THF) to form (C5H5)2Lu(NC4H2Me2(THF) (3). The 1H‐ and 13C‐NMR spectra of the new compounds as well as the X‐ray single‐crystal structure analysis of 3 are reported and discussed.
Zur Gasphasenpyrolyse von 2‐Ethinyl‐1,3‐butadien und dessen thermischer Cycloisomerisierung
Authors: Remmler Mathias , Zimmermann Gerhard , Ondruschka Bernd , Bader Hubert , Hopf Henning 
Published: July 2007

On the Gas‐Phase Pyrolysis of 2‐Ethinyl‐1.3‐butadiene and Its Thermal CycloisomerizationThe gas‐phase pyrolysis of 2‐ethinyl‐1,3‐butadiene (2) has been investigated in the 500‐to‐700°C temperature range. Besides several fragmentation products (≤C4 hydrocarbons) benzene and fulvene (5) are the main products. Under the same conditions 2‐([2‐D1]ethinyl)‐1,3‐butadiene (2a) furnishes the monodeuteriofulvenes 5a–c. The cycloisomerization of 2/2a presumably begins with an acetylene‐vinylidenecarbene rearrangement, which may be followed by a deuterium scrambling mechanism involving either benzvalene (9) or vinylcyclobutadiene (10) intermediates. When 1‐ethinyl‐1‐cyclohexene (6) is employed as a precursor for 2, styrene is produced in significant amounts besides the products observed from 2. Pyrolysis of 1‐([2‐D1]ethinyl)cyclohexene (6a) provides [D1]‐styrene whose isotopic label is scrambled over both the vinyl substituent and the aromatic nucleus.
1‐Oxa‐3‐cyclooctin
Authors: Meier Herbert , Stavridou Evaggelia , Roth Silke , Mayer Winfried 
Published: July 2007

1‐Oxa‐3‐cyclooctyneAccording to an MNDO calculation, 1‐oxa‐cyclooctyne (13) and 1‐oxa‐3‐cyclooctyne (14) are 8‐membered heterocyclic ring systems with high steric energy (ring strain). On the basis of THF (1) and acetoacetic ester (4), a multi‐step synthesis is described for 14. The triple bond is introduced in the last step by a thermal fragmentation of the 1,2,3‐selenadiazole 12.
Synthesis of New Zwitterionic Pyridazino‐as‐triazines
Authors: Juhász‐Riedl Zsuzsanna , Hajós György , G´cs‐Baitz Eszter , Kollenz Gert , Messmer András 
Published: July 2007

AbstractReaction of the furo[2,3‐e]pyrido[l,2‐b]‐as‐triazinium salt 1 with methyl hydrazine gave the zwitterionic 1‐substituted pyrido‐pyridazino‐as‐triazine 4. The neutral 2‐substituted isomer 6 was formed when 1 was treated with 1‐formyl‐1‐methylhydrazine. Reaction of 1 with 1‐acyl‐2‐methylhydrazine gave rise to 1,3,4‐trisubstituted zwitterionic derivatives of the same ring system. Efforts to synthesize aryl‐substituted zwitterions led to simultaneous formation of the desired compound 12 and of a new ring transformation product, the pyrazolopyrido‐as‐triazine derivative 15.
The N‐Substitution of Aliphatic Primary Amines via 1‐[(Alkylamino)methyl]benzotriazoles: Preparation of Secondary Amines
Authors: Katritzky Alan R. , Noble Gloen , Pilarski Boguslaw , Harris Philip 
Published: July 2007

AbstractA new method has been developed for the selective conversion of primary aliphatic amines into unsymmetrical secondary amines by Grignard reaction of 1‐[(alkylamino)methyl]‐benzotriazoles 1. This method employs simple procedure and mild conditions, and is specific in that only monoalkylation of the primary amines results.
Folgereaktionen von Sulfenen aus Sulfonylchloriden und tertiären Aminen, 1 Über die konkurrierende Bildung von Sulfen–Trialkylamin‐S,N‐ und ‐C,N‐Addukten
Authors: Opitz Günter , Rieth Karlheinz , Ehlis Thomas 
Published: July 2007

Secondary Reactions of Sulfenes from Sulfonyl Chlorides and Tertiary Amines, 1. ‐ On the Competing Formation of Sulfene ‐ Trialkylamine S,N‐ and C,N‐AdductsPhenylmethanesulfonyl chloride (1a) reacts with an excess of triethylamine in acetonitrile solution at ‐40°C to give stilbene episulfone (9a, 95%) via the phenylsulfene–triethylamine S,N‐adduct 1ah. With trimethylamine and quinuclidine the yield of stilbene is reduced by the additional formation of (benzylsulfonyl)phenylsulfene–amines S,N‐adducts 11ag and 11ae and C,N‐adducts 15ag and 15ae which was proven by reaction with dimethylamine to 16 and by hydrolysis to 17–19, respectively. 1d reacts with triethylamine yielding 94% of α‐chloro sulfones 4s and 6d via pentamethylenesulfene–triethylamine S,N‐adduct 5dh, with trimethylamine, however, C,N‐adduct 12dg is obtained which is easily oxidized to 20dg (47%). The air‐sensitive dimethylsulfene–trimethylamine C,N‐adduct 12cg was isolated and characterized.
Synthesen mit 2,4,4‐Trifluor‐1,3‐dithietan‐2‐ylium‐hexafluoroarsenat
Authors: Waterfeld Alfred 
Published: July 2007

Syntheses with 2,4,4Trifluoro‐1,3‐dithietan‐2‐ylium HexafluoroarsenateThe 2‐bromo and 2‐iodo cations ‐X (XBr, I) are prepared as stable salts 3a and 4a from the title compound ‐F AsF‐6 (1a). Salt 1a reacts with BaCS3 to yield the new cyclic thiocarbonyl compound (5). Alkylation of 5 with CF3F/AsF5 produces the trithiocarbenium salt ‐SCH3 AsF‐6 (5a). Difluorothiophosgene (7) and its trimer (F3CS)2CS (8) add to the cation of 1a to form ‐SCF3 AsF‐6 (10a), the perfluorinated analog of 5a. The cation of 10a unlike 5a adds a fluoride ion to give ‐SCF3 (10), a new isomer of 8.
Intramolecular Metalation of CH Bonds with {cis,cis‐1,3,5‐Tris[(diphenylphosphino)methyl]cyclohexane}rhodium(I) Chloride
Authors: Mayer Hermann August , Kaska William Charles 
Published: July 2007

AbstractThe novel tridentate ligand cis,cis‐1,3,5‐tris[(diphenylphosphino)methyl]cyclohexane (6) has been synthesized and treated with [Rh(COD)Cl]2. Intramolecular metalation of a CH bond of the cyclohexane ring occurs (7). Studies with D2 gas and 6[D6] prove that axial and equatorial CH bonds are metalated and that a mutual exchange occurs in this process. Replacement of the Cl− by the SbF−6 anion in 7 results in a reduced interaction between the metal and the CH bond (8). 7 reacts with CO to form the carbonyl 9 where no such interaction is observed.
Silylierungs‐ und Desilylierungs‐Experimente mit sterisch gehinderten Stannylphosphanen
Authors: Hänssgen Dieter , Aldenhoven Heinz 
Published: July 2007

Silylating and Desilylating Experiments with Sterically Hindered Stannyl PhosphanesMeP(SiMe3)2 reacts with tBu2Cl2 to give the four‐membered ring (tBu2SnPMe)2 (1). Mixed silyl‐stannyl‐substituted phosphanes tBu3SnP(SiMe3)2 (2) and tBu2Sn[P(SiMe3)2]2 (3) are obtained by metathesis of LiP(SiMe3)2 with tBu3SnCl and tBu2SnCl2, respectively. Methanolysis of 2 and 3 yields the corresponding PH compounds tBu3SnPH2 (4) and tBu2Sn(PH2)2 (5). On heating of 5, the four‐membered ring (tBu2SnPH)2 (6) is formed by a condensation reaction. The new compounds are characterized by NMR (1H, 31P, 119Sn) and mass spectroscopy.
Beiträge zur Chemie des Bors, 206. Darstellung und strukturelle Charakterisierung der p‐Formylbenzolboronsäure
Authors: Feulner Herta , Linti Gerald , Nöth Heinrich 
Published: July 2007

Contributions to the Chemistry of Boron, 206. — Preparation and Structural Characterization of p‐Formylbenzeneboronic AcidThe Grignard compound prepared from 1‐bromo‐4‐(diethoxymethyl)benzene in tetrahydrofuran reacts with tri‐n‐butoxyborane to produce the title compound in 78% yield after hydrolytic workup. The molecule crystallizes in the triclinic space group P&1bar;, Z  2, its B(OH)2 group showing extensive intermolecular hydrogen bonding. The formyl group is disordered.
Wasserlösliche Metallkomplexe und Katalysatoren, V. 2,2′‐Bipyridin‐5‐sulfonsäure und metallorganische Komplexe: Spektroskopie und Strukturchemie
Authors: Herrmann Wolfgang A. , Thiel Werner R. , Kuchler Josef G. , Behm Joachim , Herdtweck Eberhardt 
Published: July 2007

Water‐Soluble Metal Complexes and Catalysts, V. — 2,2′‐Bipyridine‐5‐sulfonic Acid and Organometallic Complexes: Spectroscopy and StructuresCoplanar orientation of the pyridine rings in 2,2′‐bipyridine‐5‐sulfonic acid (1a) and in metal complexes of this ligand is evident from NMR studies. While the free acid 1a exists as a planar zwitter‐ion the rings of the salts 1b–d (Na+, [N(C4H9)4]+,[P(C6H5)4)]+) and sulfonamides 1f–h (tert‐butyl, benzyl, 2‐pyridylmethyl) are twisted. X‐ray crystal structures determined for four complexes 4e, h, 1, and 10b of the sulfonic acid and sulfonamide derivatives of 2,2′‐bipyridine show that there is no influence of the sulfonic acid and the sulfonamide groups (meta‐position) on the complex chemistry of the chelate ligand. Variation of solubility should, therefore, occur without principal changes of reactivity.
Zur Struktur von Trithiatriazinen
Authors: Jaudas‐Prezel Evelyn , Maggiulli Roberto , Mews Rüdiger , Oberhammer Heinz , Stohrer Wolf‐Dieter 
Published: July 2007

The Structure of TrithiatriazinesMNDO and ab initio calculations have shown that the structure of trithiatriazines [(RSN)3, where R  F, Cl, {H}] is influenced by the anomeric effect and by antiaromaticity of the ring for electron pairs in axial positions. These calculations are supported by a joint electron diffraction and microwave structure determination of (NSF)3 in the gas phase.
Synthesis and reactions of novel tricyclo[4.3.1.12,5]undec‐3‐en‐10‐ones
Authors: Hoffmann H. Martin R. , Wagner Dagmar , Wartchow Rudolf 
Published: July 2007

AbstractSodium iodide/copper mediated intermolecular cyclodehalo‐genation of 2,6‐dibromocyclohexanones in the presence of furan and cyclopentadiene afforded a variety of alkylated tricyclo[4.3.1.12,5]undec‐3‐en‐10‐ones. An alkyl group (methyl or isopropyl) adjacent to the carbonyl carbon atom in the starting 2,6‐dibromocyclohexanone derivative was important for the success of the cycloaddition procedure. Even tricylic ketone 11, containing two quaternary carbon atoms adjacent to the carbonyl carbon atom, was prepared. The α,α'‐dibromoketones derived from either enantiomer of menthone and cyclopentadiene reacted enantioselectively, yielding tricycles (7R)‐7 and (7S)‐7. Since a number of tricyclic ketones 3–11 were sensitive, they were reduced to secondary alcohols 19–25, having an axial, α‐configurated OH group and were also converted into tertiary methylcarbinols 26 and 27 using methyllithium activated with tBuOK. Secondary α‐configurated alcohols 19–25 had an earthy‐mouldy odour, and tertiary carbinols 26 and 27 even more so. Unsaturated alcohols 26 and 27 showed a 4 J coupling of 2 Hz between the rigidly held OH proton and the nearest methyl protons. On hydrogenation of the olefinic double bond (4 → 33, → 34) this long‐range coupling disappeared.