bluuebunny/crossref_metadata_2025 huggingface dataset:
Pyrano[4,3‐b]pyran‐2,5‐dione, 1. Einfache Synthese von Pyranopyrano‐chinolintrionen
Authors: Saalfrank Rolf W. , Hörner Bernd
Published: July 2007

Pyrano[4,3‐b]pyran‐2,5‐diones, 1. – Convenient Synthesis of Pyranopyrano‐quinolinetriones

Reaction of malondiamides 1 with malonyl chloride (5) leads to 2,5‐dioxo‐2H,5H1‐pyrano[4,3‐b]pyrans 7, which readily react with diazomethane to give the corresponding methyl ethers 8. Thermically induced cyclisation of 8 affords 7,12‐dihydro‐2H,5H1‐pyrano[2′,3′ :4,5]pyrano [2,3‐b]quinoline‐2,5,12‐triones 9. Acidic hydrolysis of 9 yields 4H1‐pyrano[2,3‐b]quinoline‐4,5(10H)1‐diones 10, while basic hydrolysis of 9 gives 4‐hydroxy‐2(1H)1‐quinolinones 11.
Metallkomplexe in Biologie und Medizin, VI. Darstellung und Kristallstruktur von (Penicillaminato‐O,S,N)bismut(III)1‐chlorid
Authors: Herrmann Wolfgang A. , Herdtweck Eberhardt , Pajdla Liba
Published: July 2007

Metal Complexes in Biology and Medicine, VI[1]. – Synthesis and Structure of (Penicillaminato‐O,S,N)bismuth(III) Chloride

Bismuth(III) oxychloride reacts with D‐(–)1‐penicillamine to form [D‐(–)1‐penicillaminato‐O,S,N]bismuth(III) chloride (1), the solid state structure of which has been determined by single‐crystal X‐ray diffraction. The tridentate chelation of the metal center by sulfur, nitrogen, and oxygen atoms leads to the formation of five‐membered rings. Due to interaction of bismuth with oxygen atoms of the carboxy groups, a polymeric two‐dimensional structure results in the crystal lattice. Bismuth has a seven‐fold inner coordination sphere.
1,2‐Azaborolyl‐Komplexe, XXVIII. (η5‐1‐tert1‐Butyl‐2‐methyl‐1,2‐azaborolyl)carbonyl‐Phosphan‐und ‐Olefin‐Cobalt‐Komplexe
Authors: Schmid Günter , Kilanowski Bert , Boese Roland , Bläser Dieter
Published: July 2007

1,2‐Azaborolyl Complexes, XXVIII[1]. – (η5‐1‐tert1‐Butyl‐2‐methyl‐1,2‐azaborolyl)carbonyl Phosphane and ‐Olefin Cobalt Complexes

By using (η5‐1‐tert1‐butyl‐2‐methyl‐1,2‐azaborolyl)dicarbonyl‐cobalt [η51‐AbCo(CO)2] (1) as starting material, various phos‐phane and olefin derivatives of the type AbCo(CO)L are synthesized. The phosphanes LPMe3, PEt3, P(nPr)3, P(nBu)3, and P(OPh)3 give, due to the chirality of 1, the enantiomeric compounds 2–6, whereas the phosphanes P(tBu)MePh, P(OsBu)Ph2, and PPh2 [OCH(CH3)CO2CH3] form the diaster‐eoisomers 7–9. The orange‐red, oily and volatile compounds are isolated with yields between 30 and 60%. The mechanism of formation of [η51‐AbCo(CO)PMe3] (2) has been studied by means of intermediates at low temperatures. To avoid a 20e configuration when PMe3 is added to 1, the allyl complex [η31‐AbCo(CO)2PMe3] (2a) is formed. With an excess of PMe3 it can even be transferred into the mono‐hapto complex [η11‐Ab‐Co(CO)2(PMe3)2] (2b) with a Co – C‐3 s̀ bond. 2a as well as 2b change to [η51‐AbCo(CO)PMe3] (2) when warmed up to room temperature. In contrast to substitution reactions of [Cp‐Co(CO)2] where intermediates have never been observed, here an addition‐elimination process is proved. With dimethyl ma‐leate, maleic anhydride, and methylmaleic anhydride three olefin complexes 10, 11, and 12 are obtained. However, 10 contains the fumaric ester, due to a cis‐trans isomerisation during the complexation. X‐ray structure analyses prove the molecular structures of 11 and 12. The original goal of this project, namely to prepare pure enantiomeric [η51‐AbCo‐(CO)olefin] half‐sandwich complexes in order to study the ster‐eoselective influence of the Ab ring on addition reactions to the olefin ligands could not yet be reached.
AM1 and X‐ray Studies of the Structures and Isomerization Reactions of Indigo Dyes
Authors: Grimme Gabriele , Boldt Peter , Grimme Stefan , Jones Peter G.
Published: July 2007

AM1‐SCF and AM1‐SDCI calculations have been carried out for indigo and three conformers of N,N′1‐diacetylindigo in their cis and trans configurations. The molecular structure of trans‐ N,N′1‐diacetylindigo was determined by X‐ray diffraction. The calculated ground‐state data obtained within the SCF approximation (relative energies, structural parameters) are in excellent agreement with the corresponding experimental values. Potential energy curves (PEC) for the isomerization reaction cis/trans in several electronic states were obtained from AM1‐SDCI calculations. For N,N′1‐diacetylindigo the ground state PEC has a maximum at a torsion angle about the central CC bond of 90°, whereas the S1‐ and T11‐state PEC's show minima at the corresponding geometry. For indigo itself significant barriers to the photoisomerization in the S1‐ and T11‐excited states are predicted because of increased NH…OC hydrogen bonding. The results provide an explanation for the phototropic behaviour of N,N′1‐diacetylindigo and the photostability of indigo. The calculated enthalpies of activation for the isomerization process cis → trans in the ground state compare well with available experimental data, thus rendering feasible the prediction of the thermal stability of cis isomers not yet synthesized.
Substituenteneffekte auf die C – C‐Bindungsstärke, 11. Thermolyse von Tetraalkylpinacoldimethylethern
Authors: Birkhofer Hermann , Beckhaus Hans‐Dieter , Rüchardt Christoph
Published: July 2007

Effects of Substituents on the Strength of CC Bonds, 11[1]. – Thermolysis of Tetraalkylpinacol Dimethyl Ethers

The products and the kinetics of the thermolysis reaction of the pinacol dimethyl ethers 1a‐1f have been studied. A linear correlation between Δ≢ (300°C) of thermolysis and the strain enthalpies Hs of 1, or its release Ds during the dissoziation into radicals 2, is observed. From this correlation a stabilization enthalpy HR2.1 ± 0.5 kcal/mol is deduced for α1‐methoxy‐alkyl radicals 2 as compared to tert1‐alkyl radicals.
Kohlenwasserstoffverbrückte Komplexe, XXVII. C—C‐Kupplung von ungesättigten Kohlenwasserstoffen in anionischen und kationischen Komplexen. Addition der Anionen von μ1‐(Diphenylmethan)1‐, μ1‐Fluoren‐und μ1‐(9,10‐Dihydroanthracen)1‐bis(tricarbonylchrom) an koordinierte Olefin‐, Benzol‐, Cyclohexadienyl‐, Cycloheptadienyl‐und Cycloheptatrienyl‐Liganden
Authors: Wieser Michael , Karaghiosoff Konstantin , Beck Wolfgang
Published: July 2007

Hydrocarbon‐Bridged Complexes, XXVII[1]. – CC Coupling of Unsaturated Hydrocarbons of Anionic and Cationic Complexes. Addition of Anions from μ1‐(Diphenylmethane)1‐, μ1‐Fluorene‐, and μ1‐(9,10‐Dihydroanthracene)1‐bis(tricarbonylchromium) to Coordinated Olefin, Benzene, Cyclohexadienyl, Cycloheptadienyl, and Cycloheptatrienyl Ligands

Herrn Professor Herbert D. Kaesz zum 60. Geburtstag gewidmet.

The addition of the anions 1 – 3 of μ1‐(diphenylmethane)1‐, μ1‐fluorene‐, and μ1‐(9,10‐dihydroanthracene)1‐bis(tricarbonylchromium) to π1‐bonded hydrocarbons (olefin, benzene, cyclohexadienyl, cycloheptadienyl, and cycloheptatrienyl) in cationic complexes of manganese, rhenium, iron, chromium, molybdenum, tungsten, and cobalt provides a synthesis of new hydrocarbon‐bridged heterometallic complexes 4 – 10.
Organo‐substituierte Silole durch zweifache Organoborierung von Di‐1‐alkinylsilanen
Authors: Köster Roland , Seidel Günter , Süß Jürgen , Wrackmeyer Bernd
Published: July 2007

Organo‐Substituted Siloles by Twofold Organoboration of Di‐1‐alkynylsilanes

Me2Si(CCR)2 [RMe (A), Bu (B), tBu (C), iPent (D), Ph (E), Me3Si (F)], prepared from Me2SiCl2 and MCCR (MLi, Na, K), react with Et3B by 1,1‐ethyloboration to form the organo‐substituted siloles Me2 (1a – f) in high yields with different reaction rates: F > B ≈︁ D > A > C > E. Me2Si(C CiPent)(C  CPh) (H) and Et3B give a 5 : 1 mixture of the two regioisomeric substituted siloles 2 and 2′. – 1a and e are deborylated with H2NCH2CH2OH or MeCO2H to 3a and e, respectively. 1a reacts with maleic anhydride to yield the [4 + 2] addition compound 4a. With (OC)5Fe, Cp‐Co(C2H4)2, and (CDT)Ni the cycloracemic (ligand)transition metal η41‐complexes [(OC)3Fe‐1a (5a), (OC)3Fe‐3a (6a), CpCo‐3a (7a)] and the cyclodiastereomeric η4,η41‐complexes Ni‐(3a)2 (8a/8a′) are formed. All products were characterized by multinuclear NMR, including measurements of J(29Si13C) and J(13C13C).
Synthesis and Chemical Transformations of 1,3‐Diaryltetrazolium Salts. Preparation of Mercury(II) and Palladium(II) Complexes of 1,3‐Diaryltetrazolylene and Reactions of 5‐Substituted 1,3‐Diphenyltetrazolium Salts with Nucleophiles
Authors: Araki Shuki , Wanibe Yasumi , Uno Fujio , Morikawa Akinao , Yamamoto Kaori , Chiba Kyoko , Butsugan Yasuo
Published: July 2007

1,3‐Diaryltetrazolium salts 5 and 6 have been prepared by nitric acid oxidation of the corresponding 5‐thiolates 4. The reaction of 5 with mercury(II) acetate gives (1,3‐diaryltetrazolylene)mercury(II) complexes 7, which provide 5‐halotetrazolium salts 8 – 10 by treatment with halogen. 1,3‐Diphenyltetrazolylene (16), generated in situ by proton abstraction of 1,3‐diphenyltetrazolium salts 5a or 6a, has been trapped with p‐(dimethylamino)benzenediazonium tetrafluoroborate to form 18/18′. The palladium(II) complex 19 of 1,3‐diphenyltetrazolylene has been prepared by oxidative addition of tetrakis(triphenylphosphane)palladium(0) to 5‐chlorotetrazolium salt 8. The reactivity of various 5‐substituted tetrazolium salts toward carbon nucleophiles depends on the nature of the substituents at C‐5. With electronegative substituents, nucleophilic substitution proceeds at C‐5, whereas electron‐donating substituents direct the nucleophiles towards N‐2 yielding ring‐cleaved products.
Syntheses and Structures of Transition‐Metal Complexes of Mesoionic Olate, Thiolate, Selenolate, and Cyclopentadienide
Authors: Araki Shuki , Butsugan Yasuo
Published: July 2007

The dicarbonyl(η1‐cyclopentadienyl)iron(II) complex 5 of 1,3‐diphenyltetrazolium‐5‐olate (4) and the pentacarbonylmolybdenum(0) complexes 7, 11, and 9 of 1,3‐diphenyltetrazolium‐5‐thiolate (6), −5‐selenolate (10), and 5‐methyl‐1,4‐diphenyl‐1,2,4‐triazolium‐3‐thiolate (8) as well as tricarbonylchromium(0) complex 13 and ‐molybdenum(0) complex 14 of 1,3‐diphenyltetrazolium‐5‐cyclopentadienide (12) have been prepared. Their physicochemical properties are discussed on the basis of spectroscopic properties.
Synthese und Charakterisierung von substituierten Nickelhemiporphyrazinen
Authors: Hanack Michael , Haberroth Klaus , Rack Michael
Published: July 2007

Synthesis and Characterization of Substituted Nickel Hemiporphyrazines

The butoxy‐substituted (hemiporphyrazinato)nickel compounds (C4H9O)2HpNi (7), (C4H9O)4HpNi (11), and (C4H9O)6HpNi (12) are prepared from isoindolenine 4 or 4,7‐dibutoxy‐1,3‐dihydro‐1,3‐diiminoisoindole (8), 2,6‐diaminopyridines and nickel acetate. The complexes 7, 11, and 12 are soluble in common organic solvents and were characterized by 1H‐and 13C‐NMR spectroscopy.
Reactions of Electrochemically Generated Organometallics, 2. The Use of Zinc, Tin, Aluminium, Indium, and Iron as Sacrificial Anodes in the Electrochemically Assisted Reformatsky Reaction of Ethyl 2‐Bromoalkanoates with Succinic Anhydride
Authors: Schwarz Karl‐Heinz , Kleiner Katharina , Ludwig Rolf , Schick Hans
Published: July 2007

Zinc, tin, aluminium, indium, and iron were applied as sacrificial anodes in the electrochemically assisted Reformatsky reaction of succinic anhydride (1) with ethyl 2‐bromoalkanoates 2. In all cases the expected 1‐ethyl 3‐oxohexanedioates 3 were abtained in good to moderate yields. However, the amount of current consumed for the dissolution of one equivalent of anode metal strongly depends on the kind of metal. Whereas aluminium and iron require 1 Faraday per equivalent (Faraday val–1), tin demands only 0.9 Faraday val–1, and zinc and indium require an even smaller amount of current. It is assumed that in the case of the last three metals the electro‐chemical Reformatsky reaction is overlapped by a current‐independent normal Reformatsky reaction, in which the anode acts as activated metal.
Rate‐Determining Effects in the Formation of Hantzsch 1,4‐Dihydropyridines from N‐(1‐Haloalkyl)azinium Halides and Methyl 3‐Amino‐2‐butenoate
Authors: Eynde Jean‐Jacques Vanden , Mayence Annie , Maquestiau André , Anders Ernst
Published: July 2007

N‐(1‐Haloalkyl)azinium halides react with methyl 3‐amino‐2‐butenoate to yield 4‐substituted dimethyl 1,4‐dihydro‐2,6‐dimethyl‐3,5‐pyridinedicarboxylates. The rates of formation of the latter compounds are monitored by 1H‐NMR spectroscopy. Mechanistic and practical considerations are discussed.
Flüssigkristalline Verbindungen, 77. Neue makroheterocyclische Palladium‐Komplexe
Authors: Gündogan Bilgi , Praefcke Klaus
Published: July 2007

Liquid Crystals, 77[1]. – Novel Macroheterocyclic Palladium Complexes

The double cyclopalladation of the bisimine 1 affords spacious tetrapalladium complexes 2a – c which represent new thermotropic metallomesogens, the heaviest low‐molecular liquid crystals (mol. mass ≈︁ 3500 – 4000) studied so far.
Diorganomagnesium Compounds from Magnesium, Hydrogen, and 1‐Alkenes and Their Application in Synthesis
Authors: Bogdanović Borislav , Bons Peter , Konstantinović Stanimir , Schwickardi Manfred , Westeppe Uwe
Published: July 2007

1‐Alkenes are converted in high yields to the corresponding primary diorganomagnesium compounds by transition metalcatalyzed hydromagnesation reaction using catalytically prepared suspended (MgH2*) or dissolved magnesium hydride (MgH2*). The most active hydromagnesation catalysts have been found to be combinations of zirconium tetrahalides with MgH2* or MgH2*. The reaction is highly regio‐and chemoselective. The diorganomagnesium compounds prepared in situ from magnesium, hydrogen, and 1‐alkenes can be applied to the synthesis of organic and organometallic compounds just as Grignard compounds (Scheme 3, reaction 3–11). Dioctylmagnesium undergoes the growth reaction with ethene in the presence of quinuclidine and is oxidized by molecular oxygen in high yield to 1‐octanol.
Organosubstituierte 1,1′‐Spirobisilole und 1,1′‐Spirobigermole durch vierfache Organoborierung von Tetra‐1‐alkinylsilanen und ‐germanen
Authors: Köster Roland , Seidel Günter , Klopp Ingo , Krüger Carl , Kehr Gerald , Süß Jürgen , Wrackmeyer Bernd
Published: July 2007

Organosubstituted 1,1′‐Spirobisiloles and 1,1′‐Spirobigermoles by Fourfold Organoboration of Tetra‐1‐alkynylsilanes and ‐germanes[1]

Si(CCR)4 [RMe (A), RPh (B), RSiMe3 (C)] and Ge(CCR)4 [RMe (D), RPh (E)] react with Et3B by twofold intermolecular ethyloboration and twofold intramolecular vinyloboration to form the organo‐substituted 5‐sila(germa)spiro[4.4]nonatetraenes , RMe: 1a, RPh: 1b; MGe, RMe: 2d, RPh: 2e] via the mono‐and bisethyloboration compounds 3 or 4 (e.g. 3b, 4c) with different rates: Ge > Si; Me > Ph. For comparison, compounds Sn(CCR)4 [RMe (F), RPh (G)] react with Et3B in the absence of a solvent to mixtures of various spirotin compounds (5f, 5g, 6f, 8f, 9g, 10g, 11g) of which only 9g (RPh) corresponds to the spirosilanes and ‐germanes. This is the result of effective competition between intramolecular and intermolecular organoboration in the case of the tetra‐1‐alkynyltin compounds. The protodeborylation of 1a, b and 2d, e with MeCO2H leads to 12a, b and 13d, e, respectively. 12a isomerises by UV irradiation to allyl isomers 12a′. From 12a with 2 equiv. of maleic anhydride the 1:2 addition compound 14a is obtained, the autaddition of 12a, d leads to 15a, d. Spiro compound 12a reacts with (OC)5Fe or CpCo(C2H4)2 to give the cyclodiastereomeric η41‐complexes [(OC)3Fe]2‐12a (16a1–a4; X‐ray structure analysis of meso‐ 16a1), (OC)3Fe‐12a (17a) and (CpCo)2‐12a (18a1–a4). – All products were characterized by multinuclear NMR, including measurements of the coupling constants 1J(13C13C), 2J(29Si29Si), nJ(29Si13C) and nJ(119Sn13C).
2‐Boraindane und 2‐(Dialkylamino)1‐2‐benzoborol‐Dianionen
Authors: Herberich Gerhard E. , Eigendorf Uwe , Englert Ulli
Published: July 2007

2‐Boraindanes and 2‐(Dialkylamino)1‐2‐benzoborole Dianions

ortho1‐Xylene reacts with the Lochmann‐Schlosser base to produce a mixture of the potassium derivatives K2[1,2‐C6H4(CH2)2] (2) and K[2‐MeC6H4CH2] (3). Condensation of 1 + 2 with BCl2(NR2) (RMe, Et, iPr) affords 2‐(dialkylamino)1‐2‐boraindanes (1a–c) (50%). Treatment of 1a, b with LiTMP/TMEDA in THF yields dilithio derivatives [Li(tmeda)]2[C6H4(CH)2BNR2] (8a, b) (40%) which show tripledecked structures consisting of an aromatic 10′‐electron 2‐benzoborole dianion and two [Li‐(tmeda)]+ units facially bound to the borole ring. 1a reacts with HCl/Et2O/hexane to give C6H4(CH2)2BCl · OEt2 (1d · OEt2) (76%) which decomposes in vacuo to give the chloro derivative 1d. The methyl derivative C6H4(CH2)2BMe (1e) is obtained from 1a by treatment with LiMe/Et2O at –78°C and subsequently with HCl/Et2O at –78°C (41%). 1a, b react with MeOH at –78°C to give solid adducts C6H4(CH2)2BOMe · NHR2 (12a, b) while 1c affords C6H4(CH2)2BOMe (1f). Subsequent ring‐opening produces 2‐MeC6H4CH2B(OMe)2 (13). With the exception of 1b the 2‐boraindanes 1 are crystalline solids. The silylation of the 2‐benzoborole dianions and various (2‐methylbenzyl)borane derivatives is also described.
From para1‐Dimethoxybenzene Toward Crownbenzenophanes, 2. Synthesis, X‐ray Structure and Fluorescence Emission Properties of 1,3,10,13,16,19,22‐Heptaoxa(3,13)[28]paracyclophane and Its Complex with Sodium Cation
Authors: Marsau Pierre , Andrianatoandro Harimbola , Willms Thomas , Desvergne Jean‐Pierre , Bouas‐Laurent Henri , Hopf Henning , Utermöhlen Ralf
Published: July 2007

The synthesis and X‐ray molecular structure of the title compound, an heptaoxa[3,13]paracyclophane, as well as that of its 1:1 sodium complex are described; a study of the absorption and fluorescence spectra indicates that this crown‐cyclophane behaves as a hybrid between strained classical cyclophanes and large macrocycles.
Synthese von Tetravinylphthalocyanin
Authors: Beck Anton , Hanack Michael
Published: July 2007

Synthesis of Tetravinylphthalocyanine

Tetravinylphthalocyanine (5) has been prepared by heating 1,3‐dihydro‐1,3‐diimino‐5‐vinyl‐isoinodole (4) in DMAE. 5 is characterized by IR‐, UV/Vis‐, and 13C CP/MAS‐NMR spectroscopy.
Diels‐Alder Reaction of Racemic β1‐Isopropyl‐α1‐methylene‐β1‐lactone with Enantiomerically Pure 5,6,7,7a‐Tetrahydro‐7a‐methyl‐1‐phenyl‐4H1‐indene and Retro Cleavage of the Resulting Spiro‐β1‐lactones: The First Case of a Perfect Topological Resolution
Authors: Adam Waldemar , Nava Salgado Victor O. , Wegener Bernd , Winterfeldt Ekkehard
Published: July 2007

The racemic β1‐isopropyl‐α1‐methylene‐β1‐lactone 1 undergoes a configuration‐dependent, highly selective [4 + 2] cycloaddition to the enantiomerically pure cyclopentadiene 2; chromatographic separation of the adducts and subsequent thermal retro cleavage provide the pure enantiomers (S)‐1 and (R)‐1 in 99% e.e.
Darstellung und Reaktionen von (η3‐Allyl)(η5‐pentamethylcyclopentadienyl)‐cobalt(II) und seinen Derivaten
Authors: Nehl Hans
Published: July 2007

Synthesis and Reactivity of (η3‐Allyl)(η5‐pentamethylcyclopentadienyl)cobalt(II) and its Derivatives

Reaction of (η5‐pentamethylcyclopentadienyl)cobalt(II) chloride (1) with allyllithium‐ or allylmagnesium compounds leads to new (η3‐allyl)(η5‐pentamethylcyclopentadienyl)cobalt(II) complexes 2a–d. Complexes 2a reacts with acetonitrile by oxidative addition of a methyl group to cobalt to form 5. With alkynes complexes with cyclodimerisized or ‐trimerisized alkynes as ligands are formed, e.g. the tetraphenylcyclobutadiene complex 6 from 2a and tolan and the hexamethylbenzene complex 8 from 2a and 2‐butyne. Reaction with phenylethyne catalytically leads to triphenylbenzene 10. The complexes 2a–d are oxidized by iodine and bromine to Co(III) iodides 12a–d and bromides 14a and b and by ferricenium tetrafluoroborate to the tetrafluoroborates 13–c. The tetrafluoroborates give with nitriles stable complexes (nitrile‐co‐ordinated end‐on to Co), with alkynes substituted cyclopentadienyl ligands coordinated to Co are formed by cycloaddition of the allyl group and the alkyne.
Lanthanoiden‐Komplexe, V[1]. Strukturchemie ein‐ und zweikerniger Seltenerdalkoxide
Authors: Herrmann Wolfgang A. , Anwander Reiner , Scherer Wolfgang
Published: July 2007

Complexes of the Lanthanides, V[1].–Structural Chemistry of Monomeric and Dimeric Rare Earth Alkoxides

The first sublimable monomeric yttrium „CH‐alkoxide”︁ Y[OC‐(iPr)(tBu)2]3 (3) is obtained by the reaction of „CH‐alcohol”︁ HOCiPr(tBu)2 („H‐proditox”︁, 1) with Y[N(SiMe3)2]3 (2). The importance of metal‐ion size and ligand sphere for nucleation is demonstrated for the system „Ln/ditox/acetonitrile”︁. The crystal structure data of dimeric 4 (Ln=Nd) and monomeric 5 (Ln=Dy) once again support the ionic nature of lanthanide alkoxide complexes.
Synthesis, X‐ray and Electronic Structure of Trinickel Tetradecker Sandwich Complexes {(η5‐C5H5)Ni[μ,η5‐(CR1)2(BR2)2CR3]}2Ni
Authors: Siebert Walter , Herter Wilfried , Schulz Hartmut , Huck Stefan , Pritzkow Hans , Zhu Longgen , Eisenstein Odile
Published: July 2007

The reduction of the 18‐VE complexes (η5C5H5)Ni[η5‐(CR1)2(BR2)2CR3] (2a, b) with potassium in THF leads to the paramagnetic anions 2–, which react with NiBr2 · DME to give the triple‐decker complexes (η5‐C5H5)Ni[μ,η5‐(CR1)2(BR2)2CR3]Ni(η5‐C5H5) (3a, b) and the tetradecker {(η5‐C5H5)Ni[μ,η5‐(CR1)2(BR2)2CR3]}2Ni (4b). Surprisingly, 4b is also obtained by heating the double‐decker complex 2b and H2AlOCMe3 in THF. The reaction between 2c and AlH3 in Et2O leads to the substitution of the ethoxy groups at the boron atoms and to the formation of the tetradecker 4d with four B–H groups. Heating of the 1,3‐benzodiborole ligand 1e and [(C5H5)Ni(CO)]2 in toluene yields small amounts of 2e and 3e, and the tetradecker 4e. X‐ray structure analyses were performed for 4d and 4e. Complex 4d is centrosymmetric with relatively short nickel‐to‐bridging ligand distances (1.69, 1.70 Å). In the tetradecker 4e the two bridging ligands adopt a synclinal conformation (rotating about 36° resp. 41° against each other). The Ni–Ni distance (3.42, 3.43) is slightly longer than in 4d (3.39 Å). The electronic structures of the tripledecker cation 3+ (32 VE) and of the tetradecker 4 (46 VE) have been investigated by means of the Fenske‐Hall method. The findings are in agreement with the experimental results that 3+ is a triplet species and 4 possesses a closed‐shell electron configuration.
Preparation and Properties of New Methano‐Bridged Dibenzo[c,g]phenanthrenes
Authors: Puls Carsten , Stolle Andreas , Meijere Armin De
Published: July 2007

Intramolecular Friedel‐Crafts alkylation of 1‐(hydroxymethyl)[5]helicenes 1‐R and 15‐Me leads to 10,11‐methano‐bridged dibenzo[c,g]phenanthrenes 2‐R and 16‐Me, respectively. These molecules are shaped like the back of a turtle as shown by X‐ray crystal structure analysis. Their nonplanarity, however, is not rigid, as revealed by the temperature dependence of their 1H‐NMR spectra. With inversion barriers of about 62.4 and 67.1 kJ mol–1 2‐H and 2‐Me are surprisingly flexible. A remarkable diastereoselectivity is observed in the addition of methyl‐ and phenylmagnesium bromide to 1‐formyl[5]helicenes 14‐Me leading to secondary alcohols 15a, b‐Me, which cyclize to bridged hydrocarbons 16a, b‐Me, in which the substituents R=Me, Ph are in the thermodynamically less favorable endo‐position. Upon heating, endo‐16a,b‐Me isomerize to exo‐6a, b‐Me irreversibly.
Substituenteneffekte auf die C–C‐Bindungsstärke, 12[1]. Thermolysen aromatischer Pinakol‐dimethylether zur Bestimmung der Stabilisierungsenergie von α‐Methoxybenzyl‐Radikalen[2]
Authors: Birkhofer Hermann , Beckhaus Hans‐Dieter , Peters Karl , Schnering Hans‐Georg Von , Rüchardt Christoph
Published: July 2007

Substituent Effects on the C–C Bond Strength, 12[1].–Thermolysis of Aromatic Pinacol Dimethyl Ethers and Stabilisation Energies of α‐Methoxybenzyl Radicals[2]

The phenyl‐substituted pinacol dimethyl ethers meso‐ and DL‐ 5a–d have been prepared by reductive dimerisation of the dimethyl acetals 7a–d of the ketones 8a–d. 1H‐NMR spectra and GC‐retention times are used to distinguish between the diastereomers, and an X‐ray structure analysis of meso‐5a confirms these distinctive criteria. The products and the kinetics of the thermolysis reaction of 5a–d have been studied. A linear correlation between ΔG+ (300°C) of thermolysis and strain enthalpies Hs of 5, or its release Ds during the dissoziation into radicals 6, is observed. These correlations do not differ from those of the thermolysis of tetraalkyl‐diphenylethanes (1, R=alkyl, S=phenyl)[3,20a]. Hence, the methoxy group does not influence the homolysis reaction of the C–C bond in 5compared to an alkyl group. It is concluded that any stabilisation of the radicals 6 by the alkoxy group[1] is canceled by an extra stabilisation of 5 by the geminal phenyl/methoxy pairs.
Synthese mittlerer und großer Ringe, XXXIII[1]. Optisch aktive 3a,6‐Methanohydroazulene durch chirale Induktion der photochemischen Festkörperumlagerung von Bis(1,2:5,6‐di‐O‐isopropyliden‐α‐D‐ und ‐α‐L‐glucofuranos‐3‐O‐yl)‐3,6‐hexanooxepin‐4,5‐dicarboxylat
Authors: Tochtermann Werner , Schlösser Ulrike , Ott Frank , Popp Brigitta , Sdunnus Norbert , Snatzke Günther , Peters Eva‐Maria , Peters Karl , Schnering Hans Georg Von
Published: July 2007

Synthesis of Medium and Large Rings, XXXIII[1].–Optically Active 3a,6‐Methanohydroazulenes via Chiral Induction of the Solid‐State Photochemical Rearrangement of Bis(1,2:5,6‐di‐O‐isopropylidene‐α‐D‐ and ‐α‐L‐glucofuranos‐3‐O‐yl) 3,6‐Hexanooxepine‐4,5‐dicarboxylate

Irradiation of an aqueous suspension of the crystalline 3,6‐hexanooxepine‐4,5‐dicarboxylic esters 2a and 2b affords the (3aS,6R,8aR)‐ and (3aR,6S,8aS)‐methanohydroazulenes 3a and 4b in 54–58% yield with 92–93% de. Irradiation of an ethereal solution of 2a–2d on the other hand proceeds with low diastereoselectivity. The absolute configurations were established by X‐ray structural analysis of the dimenthyl ester (+)‐3d, comparison of CD spectra and chemical transformations. The origin of the high diastereoselectivity of the rearrangements 2a → 3a and 2b → 4b in the solid state is discussed on the basis of the X‐ray structural analysis of the 3,6‐heptanooxepine (–)‐5a. Procedures for the removal of the chiral auxiliaries are described. Di‐O‐isopropylidene‐α‐L‐glucofuranose is recycled in 95% yield.
Multibridged [3n]Cyclophanes, 1. Synthesis of [34](1,2,3,5)‐ and ‐(1,2,4,5)Cyclophanes
Authors: Shinmyozu Teruo , Kusumoto Shirou , Nomura Sachiyo , Kawase Haruo , Inazu Takahiko
Published: July 2007

The acid‐catalyzed cyclization of a pseudogeminally substituted acetyl group and a chloromethyl group of tri‐bridged cyclophane 7, followed by reduction of the carbonyl group afforded [34](1,2,3,5)cyclophane 3. One‐step TosMIC coupling reaction of tetrabromide 12 and subsequent reduction of the carbonyl groups provided an isomer of 3, [34](1,2,4,5)cyclophane 4.
Synthesis of 4‐Aminopyrimidines from 1,2,4‐Oxadiazoles, V[1]. Reductive Formation of 2‐(Benzoylamino)indole from 3‐(2‐Aminobenzyl)‐5‐phenyl‐1,2,4‐oxadiazole and Its Transformation to 6‐Phenyl‐8H‐pyrimido‐[1,6‐a: 4,5‐b']diindole, a New Heterocyclic Ring System
Authors: Bata Imre , Korbonits Dezső , Kolonits Pál , Podányi Benjamin , Takácsy‐Erős Tünde , Simon Kálmáan
Published: July 2007

Catalytic hydrogenation of 5‐substituted 3‐(2‐aminobenzyl)‐1,2,4‐oxadiazoles 7 give 2‐(acylamino)indoles 10. Treatment of 2‐(benzoylamino)indoles 10a–c with acid leads to the novel 6‐phenyl‐8H‐pyrimido[1,6‐a: 4,5‐b']diindoles 19a–c. A route for the new ring formation is proposed. Catalytic hydrogenation of 19a (Raney nickel, 70°C, atmospheric pressure) saturates the 6‐phenyl ring but leaves the pentacyclic ring system intact. The structure of 19a is confirmed by an X‐ray crystallographic analysis.
On the Reaction of Nitrilium and N‐Acylamidinium Salts with Oximes and Other Hetero Nucleophiles
Authors: Glocker Michael O. , Shrestha‐Davadi Prativa Bade , Küchler‐Krischun Jonna , Hofmann Josef , Fischer Helmut , Jochims Johannes C.
Published: July 2007

Nitrilium salts 2 add oximes 1 to form stable alkylideneaminooxy‐substituted iminium salts 4. Compounds 4 have been postulated by Meerwein as intermediates of the Beckmann rearrangement of oximes[1]. For (E)‐4c an X‐ray structural analysis is performed. Other intermediates of the Beckmann rearrangement are the N‐acylamidinium salts 5, which are produced by the reaction of nitrilium salts with amides. As models for the transformation of 5 into amides, the end products of the Beckmann rearrangement, reactions of N‐acylamidinium salts with nucleophiles, e.g. oximes, alcohols, water, amines, thiols, and benzophenone imine are studied.
Organische Synthesen mit Übergangsmetall‐Komplexen, 64[1]. 1,4‐Diaminonaphthaline über Ketenimin‐Komplexe aus (β‐Aminovinylcarben)chrom‐Komplexen und Isocyaniden
Authors: Aumann Rudolf
Published: July 2007

Organic Syntheses via Transition Metal Complexes, 64[1]. – 1,4‐Diaminonaphthalines via Ketenimine Complexes from (β‐Aminovinylcarbene)chromium Complexes and Isocyanides

The thermal reaction of (dienylcarbene)chromium complexes (= 1‐chroma‐1,3,5‐trienes) with isocyanides provides a mild and regiospecific access to aromatic amines. Thus, 1,4‐diamino‐2‐ethoxynaphthalines 6a–d [1‐NHc‐C6H11; 4‐NRR1 = NMe2 (a) (S)‐2‐hydroxymethylpyrrolidinyl (b) (1R,2S)‐2‐methylamino‐1‐phenyl‐1‐propanol (c), NtBuMe (d)] are obtained by the cyclization of (E)‐(β‐aminostyrylcarbene)chromium complexes (CO)5Cr=C(OEt)CHC(NRR1)C6H5 [(E)‐3a–d] with cyclohexyl isocyanide (4) at 90°C in 72–85%. The aminocarbene complexes (E)‐3a–d are accessible with high stereoselectivity [>95% (E) configuration] and chemical yields of 91–96% by the addition of secondary amines HNRR1 2a–d to the (1‐alkoxy‐3‐phenylpropynylidene)chromium complex (CO)5Cr=C(OEt)C≡CC6H5 (1). 3 and 4 give initially mono‐ and bis(isocyanide) complexes, e.g. (E)‐8a and (E)‐9a, and subsequently dienylketenimine complexes by the insertion of 4 into the MC bond of 3. Dienylketenimine complexes are key intermediates in the formation of 6.
[α‐(Dimethylamino)benzyllithium–Diethyl Ether]2, (S)‐α‐(Methylpivaloylamino)benzyllithium – (–)‐Sparteine, and [3‐Iodo‐2‐lithio‐1‐methylindole – 2 Tetrahydrofuran]2: Crystal Structure Investigations of α‐Lithiated Amines
Authors: Boche Gernot , Marsch Michael , Harbach Jürgen , Harms Klaus , Ledig Burkhard , Schubert Frank , Lohrenz John C. W. , Ahlbrecht Hubertus
Published: July 2007

In order to determine whether α‐metalated (lithiated) amines are carbenoids, as are α‐lithiated halides and ethers, we have determined the crystal structures of the title compounds. In [α‐(dimethylamino)benzyllithium–diethyl ether]2 ([9 · OEt2]2) lithium bridges the anionic carbon and the nitrogen atom which corresponds to the most stable calculated model structure of LiCH2NH2. The C–N bond is only slightly (≈ 3 pm) elongated (compared to the neutral species). If one of the N‐methyl groups in [9 7dot; OEt2]2 is replaced by a pivaloyl group as in (S)‐α‐(methylpivaloylamino)benzyllithium – (–)‐sparteine (10 dot; sparteine), a five‐membered ring chelate is formed with Li being bound to the benzylic carbon atom and the oxygen atom of the pivaloyl group. In agreement with model calculations avoidance of the bridged structure as in [9 · OEt2]2 is compensated energetically by the chelate. Again a very small C–N bond elongation (≈ 3 pm) is observed. In [3‐iodo‐2‐lithio‐1‐methylindole – 2 THF]2 ([12 · 2 THF]2) lithium again does not bridge to the indole nitrogen atom because it is a weak donor. The C–N bond length to the anionic C atom is slightly longer (2–3 pm) than in the non‐lithiated compound. Other α‐lithiated amines, which have been published, although not analyzed so far under this particular aspect, show also a marginal C–N bond lengthening. However, since α‐lithiated amines – in contrast to α‐lithiated halides and ethers – until now have not been reported in the literature to react with nucleophiles RLi, there is no need to include them into the group of the above mentioned carbenoids – at least not to date.
Organophosphorverbindungen, 71[1]. Phosphaalkine und Phosphaalkene als Abfangpartner für 1,2‐Dehydrobenzol und Phenylium‐2‐carboxylat[2]
Authors: Breit Bernhard , Regitz Manfred
Published: July 2007

Organophosphorus Compounds, 71[1]. – Phosphaalkynes and Phosphaalkenes as Trapping Partners for 1,2‐Dehydrobenzene and Phenylium‐2‐carboxylate[2]

The reaction of benzene‐1‐diazonium‐2‐carboxylate (6) and of diphenyliodonium‐2‐carboxylate (7) with the phosphaalkynes 4 under thermal conditions leads to the formation of the 1,2‐dihydro‐1,3‐diphosphetes 10. With the phosphaalkenes 12 the benzenediazoniumcarboxylate 6 reacts with loss of nitrogen to give the so far unknown arylphosphaalkenes 13, the methanolysis of which afford the acylarylphosphanes 14. 1,2‐Dehydrobenzene (1), generated by β‐elimination starting with 15 or 16, does not react with the phosphaalkyne 4a (→ 5, R = tBu) but can be trapped by an insertion reaction with the phosphaalkenes 12 with formation of 17.
Umlagerungsreaktionen von Metallodiphosphapropenen des Typs (η5‐C5Me5)(CO)2FeP(SiMe3) — P = C(R)(SiMe3) (R = SiMe3, Ph)
Authors: Weber Lothar , Kirchhoff Ralf , Boese Roland
Published: July 2007

Rearrangements of the Metallodiphosphapropenes (η5‐C5Me5)(CO)2FeP(SiMe3 — P = C(R)(SiMe3) (R = SiMe3, Ph)

Heating of a methylcyclohexane solution of (η5‐C5Me5)‐(CO)2FeP(SiMe3) — P = C(SiMe3)2 (1a) gives rise to the insertion of the P = C moiety into the CH bond of a ring methyl group with formation of the chelate complex η5‐ηC5Me4CH2P‐[CH(SiMe3)2]P(SiMe3)Fe(CO)2 (2) which is converted into the pentacarbonylchromium derivative [5‐C5Me4CH2P[CH‐(SiMe3)2]P(SiMe3)[Cr(CO)5]Fe(CO)2] (3). In contrast, a similar treatment of (5‐C5Me5)(CO)2FeP(SiMe3) — P = C(Ph)(SiMe3) (1 b) furnishes the diphosphirane (5‐C5Me5)(CO)2FeP — C(Ph)‐SiMe3) — P (SiMe3) (5). By chromatography of its (CO)5Cr adduct 6, the P — Si bond is hydrolyzed to give the (diphosphirane)‐chromium complex [(5‐C5Me5)(CO)2FeP‐C(Ph)(SiMe3)P(H)]‐Cr(CO)5 (8). The molecular structures of 3 and 8 are determined by single‐crystal X‐ray analysis.
Derivatchemie des Clusters Ru4(CO)12(μ4‐η2‐N2Et2)
Authors: Hansert Bernhard , Vahrenkamp Heinrich
Published: July 2007

Derivative Chemistry of the Cluster Ru4(CO)12(μ4η2‐N2Et2)

The title compound (1) can be converted into H2Ru4CO)11(μ4‐η2‐N2Et2) (2) in three ways: a) by direct hydrogenation, b) by a H—/H+ sequence, c) by reduction with Na/Hg (reversible with FeCp2+/CO) and subsequent protonation. The structure of 2 has been determined by an X‐ray analysis. 2 is a dibasic acid and shows ligand fluxionality as demonstrated by NMR. 2 adds phenylacetylene either by insertion into one Ru—H bond or by H2 replacement yielding HRu4(CO)10(μ4‐N2Et2)(μ‐CPhCH2) (3) or Ru4(CO11(μ4‐N2Et2)(μ4‐HCCPh) (4).
Preparative, spectroscopic, and structural studies on some new silylamines
Authors: Mitzel Nobert W. , Riede Jürgen , Schier Annette , Paul Martin , Schmidbaur Hubert
Published: July 2007

The synthesis and characterization of two complete series of benzyl(phenylsilyl)amines (PhH2Si)x(PhH2C)3 — xN, benzyl(p‐tolylsilyl)amines (p‐H3CC6H4H2Si)x(PhH2C)3 — xN, and of bis‐(p‐tolylsilyl)amine are described. The compounds have been prepared from the corresponding amines and chlorosilanes with triethylamine as the auxiliary base. Bis(phenylsilyl)(trimethylsilyl)amine, (PhH2Si)2NSiMe3 (10), was obtained by the reaction of lithium bis(phenylsilyl)amide with chlorotrimethylsilane. Crystal structure analyses reveal that dibenzyl(p‐tolylsilyl)amine (7) and 10 contain planar nitrogen atoms. Heteronuclear NMR spectra (1H, 13C, 15N, and 29Si) have been measured for all compounds. The 15N chemical shifts are shown to be sensitive to variations of the geometry at the nitrogen atom. The coupling constants 1J(15N29Si) show a linear correlation with the N—Si bond lengths.
Synthesis of tetrakis[(tri‐tert‐butylphosphane)gold(I)]phosphonium salts and crystal structure of the tetraphenylboroxinate salt {[(tBu)3PAu]4P}+ [O(PhBO)2BPh2]—
Authors: Zeller Edgar , Beruda Holger , Schmidbaur Hubert
Published: July 2007

The reaction of (Me2Si)3P with {[(tBu)3PAu]3O}+ BF4– in tetrahydrofuran at —78C affords the compound {[(tBu)3‐PAu]4P}+ BF4— (1a) in high yield. This product is converted into the tetraphenylborate salt (1b) by treatment with Na[BPh4]. The two compounds have been identified on the basis of their analytical and spectroscopic data, but could not be crystallized. In attempts to prepare single crystals of 1b, a crystalline salt {[(tBu)3PAu]4P}+ [O(PhBO)2BPh2]— (1c) has been obtained in very small quantities, probably by partial anion hydrolysis. A single crystal X‐ray diffraction study of 1c CH2Cl2 shows the compound to be built up of cations with a strongly distorted tetrahedral (PAu)4P skeleton and anions with a planar six‐membered boroxine ring. Two of the phenyl groups are attached to two trigonal‐planar boron atoms and the other two phenyl groups to the third (tetrahedral) boron atom of the heterocycle. The origin of the peculiar cation structure is discussed in the light of findings with related ammonium‐ and arsonium‐centered gold clusters.
Reaktionen cyclischer Oxalylverbindungen, 35. Untersuchung von Reaktionsmechanismen durch Isotopenmarkierung, 11. Zur Umsetzung von 4‐Benzoyl‐5‐phenylfuran‐2,3‐dion mit S‐Heterocumulenen — Präparative und mechanistische Aspekte
Authors: Heilmayer Werner , OliverKappe C. , Sterk Heinz , Kollenz Gert , Peters Karl , Peters Eva‐Maria , Schnering Hans Georg Von , Walz Leonhard
Published: July 2007

Reactions of Cyclic Oxalyl Compounds, 35[1]. — Mechanistic Investigation Aided by Isotopic Labeling, 11[2]. — On the Reaction of 4‐Benzoyl‐5‐phenylfuran‐2,3‐dione with S‐Heterocumulenes — Preparative and Mechanistic Aspects[3]

The furan‐2,3‐dione 1 combines with N‐sulfinylamines or sulfur diimides to afford the pyrrole‐2,3‐diones 2, while with N‐tosylsulfinylamine the (α‐iminobenzyl)furandione 3 is obtained. (α‐Iminobenzyl)pyrrolediones 4 are formed in the reaction of 2c with N‐tosylsulfinylamine or from 3 with N‐tosylsulfur diimides. Diisopropylcarbodiimide and the pyrroledione 2c or the (iminobenzyl)furandione 3a undergo [4 + 2] cycloaddition reactions accompanied by novel and surprising rearrangements to furnish the bicyclic compounds 5 and 6, respectively. The molecular skeleton of 6 was confirmed by an X‐ray diffraction analysis. With the aid of 17O‐labeling experiments and 17O‐NMR spectroscopy mechanistic pathways including novel rearrangements were made evident.
Phosphanalkylene, 54[1a]. Kumulierte ylide, 21[1b]. Ein neuer weg zu N‐substituierten (triphenylphosphoranyliden)keteniminen
Authors: Bestmann Hans Jürgen , Hotz Michael , Witschel Matthias , Roth Dieter
Published: July 2007

Phosphane Alkylenes, 54[1a]. – Cumulated Ylides, 21[1b]. – A New Way to N‐Substituted (Triphenylphosphoranylidene)‐ketenimines

Reaction of methylenetriphenylphosphorane (1) with isothiocyanates 5 leads to ylides 6B, which can be methylated at the S atom to give the phosphonium salts 8. Treatment of 8 with sodium methanolate gives rise to formation of the phosphoranes 10, which on treatment with sodium bis(trimethylsilyl)‐amide undergo β‐elimination to form the N‐substituted (tri‐phenylphosphoranylidene)ketenimines 3.
CFNO‐Isomere — Theoretische und experimentelle Studien
Authors: Jacobs Jürgen , Jülicher Bernd , Schatte Gabriele , Willner Helge , Mack Hans‐Georg
Published: July 2007

CFNO Isomers — Theoretical and Experimental Studies

Geometrical parameters, relative thermodynamic stabilities, and vibrational wavenumbers have been calculated for six CFNO isomers by using various ab initio methods. The results are compared with those of the respective CHNO species. In noble gas matrices the most stable CFNO isomer fluoroisocyanate, FNCO, was prepared by photolysis of FC(O)N3 as well by the reaction FN + CO and FCN + O. The short‐lived intermediate (fluorocarbonyl)nitrene, FC(O)N, formed during photolysis of FC(O)N3, was trapped as FC(O)NCO in a CO matrix. In each case the courses of the investigated matrix reactions were rationalized by identification of nearly all products and the time dependence of their formation. For the FNCO molecule a complete vibrational spectrum including 15N‐, 13C‐, and 18O‐isotopic data was measured which enabled calculation of its general valence force field.
Chemoselectivity in Catalytic Transfer Hydrogenation — Reduction of Alkenes and Alkynes with the H2PO2—NH4+ · H2O/Pd‐C System
Authors: Khai Bui The , Arcelli Antionio
Published: July 2007

The H2PO2—NH4+ · H2O/Pd‐C system acts as an unusually powerful reducing agent, which is able to reduce cyclooctene to cyclooctane, Δ9,10‐octalin to decalins, α‐ and β‐pinenes to pinanes at room temperature in high yield without the formation of byproducts. This system selectively reduces each of these compounds or partly (alkynes to alkenes), depending on the competition between the transfer hydrogenation to give alkanes and the protonolysis to give hydrogen gas on the palladium catalyst.
Functionalized Enantiomerically Pure [1.1.1]‐, [2.1.1]‐, [2.2.1]‐, and [2.2.2]Triblattanes
Authors: Müller‐Bötticher Hermann , Fessner Wolf‐Dieter , Melder Johann‐Peter , Prinzbach Horst , Gries Stefan , Irngartinger Hermann
Published: July 2007

The methylene (2, 7, 10) and spirocyclopropane derivatives (8, 11, 12) are made accessible from rac‐trishomocubane(mono‐, di‐, tri‐)ones and optically pure unsaturated and benzoannulated [2.1.1]‐ (19, 48), [2.2.1]‐ (30, 53), and D3‐symmetrical [2.2.2]triblattanes (3, 4) from the enantiomers of these ketones by expeditious (one pot) ring enlargement and olefination procedures. In the case of the central [2.2.2]trienes (+)‐3/(—)‐3, novel members of the (CH)14 family, optical resolution is advantageously postponed to the stage of the intermediate [2.2.2]triones (35, 41) and effected via their (R,R)‐2,3‐butanediol acetals. In the α‐diketone series only the [2.1.1]dione (70) is sufficiently stable to allow isolation; tetrone 73 and hexone 5 are indirectly identified as quinoxalines 74 and 76, respectively. Tribenzo[2.2.2]triblattane (—)‐4 is established as the M‐helical enantiomer by X‐ray crystallography. Generally the thermal stabilization pathway of unsaturated and benzoannulated triblattanes is a [4 + 2] cycloreversion with the primary cycloreversion products [e.g. (1α,2α,7α,10α)‐tricyclo[8.4.0.02,7]tetradeca‐3,5,9,11,13‐pentaene (78) from rac‐3] being unstable under the drastic reaction conditions required. The stereochemical course of the perepoxidation of rac‐3 is investigated.
Organofluorverbindungen und Fluorierungsagenzien, 9. Von Glycosylfluoriden zu chiralen Kronenethern
Authors: Miethchen Ralf , Gabriel Torsten
Published: July 2007

Organofluorine Compounds and Fluorinating Agents, 9[1a]. — From Glycosyl Fluorides to Chiral Crown Ethers

Methyl D‐galactofuranoside (1), methyl D‐glucofuranoside (3), 3‐O‐substituted 1,2:5,6‐di‐O‐isopropylidene‐α‐D‐glucofuranoses (5a—g), 1,2‐O‐isopropylidene‐3,5,6‐tri‐O‐methyl‐α‐D‐glucofuranose (7) as well as the trans‐decalin analog 1,2‐O‐ethanediyl‐3,4,6‐tri‐O‐methyl‐β‐D‐glucopyranose (13) are selectively transformed with deacetalisation into the corresponding acylated glycosyl fluorides 2, 4, 6a—g, 8, and 14 by HF/nitro‐methane/carboxylic acid anhydride. The reaction is realized without change of the ring size if the three‐component agent system is mixed some time before the carbohydrate is added. 3,5,6‐Tri‐O‐methyl‐2‐O‐pivaloyl‐D‐glucofuranosyl fluoride (8) and 2‐O‐(2‐acetoxyethyl)‐3,4,6‐tri‐O‐methyl‐α‐D‐glucosyl fluoride (14) are used as starting materials to synthesize three isomeric, chiral crown ethers, the bis‐β‐D‐glucofuranosido‐12‐crown‐4 derivative 12 and both stereoisomeric bis‐D‐glucopyranosido‐12‐crown‐4 derivatives 20 and 21.
Gas‐Phase Generation and Characterization of Hydrogen Cyanide N‐Methylide
Authors: Goldberg Norman , Iraqi Muhammad , Schwarz Helmut
Published: July 2007

The recently described (Maier et al.[2]) title compound is not only viable in an argon matrix (10 K) but is also accessible in the gas phase. Electron impact ionization of (CH3)3CCX2NC (X = H, D) gives rise to HCNCX2+, which can be successfully neutralized in a beam experiment.
Octa‐, Hexa‐, and Tetracoordination in Tin(IV) Derivatives of cis‐β‐(Methylthio)stilbene‐α‐thiol
Authors: Schrauzer Gerhard N. , Chadha Raj K. , Zhang Cheng , Reddy Hussain K.
Published: July 2007

The S‐methyl‐cis‐stilbene‐α,β‐dithiolate of Sn(IV), Sn[Ph(S)C=C(SCH3)Ph]4, has an octacoordinate structure with two sets of four covalent and coordinate Sn–S and Sn–S(CH3) bonds of 2.425(3) and 3.599(3) Å, respectively. Both types of Sn–S bonds are close to being tetrahedral, the coordination geometry is a distorted cube. This unprecedented structure appears to involve conventional covalent and outer‐sphere coordinative Sn–S bonds. In the diphenyl derivative Ph2Sn[Ph(S)C=C(SCH3)Ph]2 the SnC2S2 core formed by the covalent Sn–C and Sn–S(thiolato) bonds is tetrahedral, but two coordinate outer‐sphere Sn‐S(CH3) bonds of 3.500(3) Å are also present. In the related SnCl2[Ph(S)C=C(SCH3)Ph]2 the presence of the polar Sn–Cl bonds prevents outer‐sphere bonding; the coordination geometry is distorted octahedral. In the triphenyltin derivative Ph3Sn[Ph(S)C=C(SCH3)Ph] the coordination geometry is tetrahedral, the thiol‐thioether ligand being monodentate with the SCH3 group in a non‐interactive position.
Zur Synthese und Charakterisierung von Platincyclobutadien‐Komplexen durch Reduktion von Hexachloroplatinsäure
Authors: Steinborn Dirk , Nünthel Ralph , Sieler Joachim , Kempe Rhett
Published: July 2007

Synthesis and Characterization of Platinumcyclobutadiene Complexes by the Reduction of Hexachloroplatinic Acid

Hexachloroplatinic acid is reduced in 1‐butanol in the presence of an alkyne R–C≡C–R′ (R, R′ = Me, Et, nPr) to give platinumcyclobutadiene complexes [PtCl2(C4R2R2′)] (1). H[PtCl3(CH3CH2CH=CH2)] (2) is an intermediate which is isolated as bis(triphenylphosphoranylidene)ammonium salt (PPN‐salt) [PPN][PtCl3(CH3CH2CH=CH2)] (3). The molecular structure of [PtCl2(C4Et4)] (1b) shows in the solid state a planar cyclobutadiene ring with internal bond angles of 93(3) and 87(2)°. The Pt–C bond lengths are 208(2) and 210(2) pm. The ethyl groups are pushed out of the ring plane, away from the Pt atom, with an angle of 7(2)°.
Darstellung und Eigenschaften von und Reaktionen mit metallhaltigen Heterocyclen, LXXXV. Konsekutive Insertions‐ und [2 + 2]‐Cycloadditions‐Reaktion von Hexafluor‐2‐butin mit einem (η2‐Thiophosphinito)cobalt‐Komplex
Authors: Lindner Ekkehard , Schlenker Tilman , Fawzi Riad , Steimann Manfred
Published: July 2007

Metal‐Containing Heterocycles: Preparation, Properties and Reactions, LXXXV[1]. – Consecutive Insertion and [2 + 2] Cycloaddition Reaction of Hexafluoro‐2‐butyne with an (η2‐Thiophosphinito)cobalt complex

Insertion of hexafluoro‐2‐butyne (2) into the Co—P bond of the (η2‐thiosphosphinito)cobalt complex (OC)2Ph3PCo(η2‐SPt2) (1) and subsequent [2 + 2] cycloaddition to a second alkyne 2 results in the formation of the stable (η3‐cyclobutenyl)cobalt complex 3. According to an X‐ray structural analysis 3 crystallizes in the triclinic space group P1 with Z = 2.