bluuebunny/crossref_metadata_2025_split huggingface dataset:
9,10‐Phenanthrenocyaninatoeisen(II) (PhcFe) und axial koordinierte Isocyanid‐Komplexe
Authors: Hanack Michael , Renz Günter 
Published: July 2007

9,10‐Phenanthrenocyaninatoiron(II) (PhcFe) and Axially Coordinated Isocyanide Complexes9,10‐Phenanthrenocyaninatoiron(II) (PhcFe) is synthesized from 9,10‐dicyanophenanthrene (3) and pentacarbonyliron. PhcFe exhibits similar spectroscopic properties (UV/VIS and Mößbauer spectra) and similar oxidation potentials as 1,2‐Naphthalocyaninatoiron(II) (1,2‐NcFe) and Phthalocyaninatoiron(II) (PcFe). Isocyanides RNC (R = tBu, cHx, Bzl, Me2Ph) react with PhcFe to form the corresponding bisaxially substituted 9,10‐phenanthrenocyaninatoiron(II) compounds 4–7. Reaction of PhcFe with 1,4‐diisocyanobenzene (dib) yields the bridged complex [PhcFe(dib)]n.
Synthese und Eigenschaften kalamitischer Flüssigkristalle aus desoxygenierten Kohlenhydrat‐Derivaten
Authors: Pudlo Peter , Thiem Joachim , Vill Volkmar 
Published: July 2007

Synthesis and Properties of Calamitic Liquid Crystals from Deoxygenated Carbohydrate DerivativesTreatment of the L‐arabino‐ and Llyxo‐configurated glycals 1 and 7 with trimethylsily cyanide leads to the formation of the anomeric nitriles 2, 3 and 15, 17, respectively. The configurational assignments are based on hydrogenated products such as 6 or 8 and 10. Depending on the configurations of the olefinic nitril sugars, various hydrogenation results are observed using palladium/charcoal or the Wilkinson catalyst. Methanolysis provides the corresponding methyl esters. The preparation of liquid‐crystalline derivatives follows the classical route. In comparing the properties of these saccharide‐based liquid crystals with the corresponding cyclohexane derivatives, the dominant influence of the anomeric effect on the tendency for phase formation can be observed. Some of the novel derivatives show highly twisted cholesteric and wide blue phases.
Vinamidin‐Chelate des Bors
Authors: Kuhn Norbert , Kuhn Annette , Speis Martin , Bläser Dieter , Boese Roland 
Published: July 2007

Vinamidine Boron Chelate CompoundsThe chelate compound 7 is obtained by the reaction of the vinamidine 6 with Et2O ‐ BF3. Protonation with HBF4 gives the cation 11. Comparison of the calculated and experimentally determined structures demonstrates 7 and 11 to be heterocyclic analogues of the cyclohexadienide 5 and 1,4‐cy‐cyclohexadiene (12).
Zur Kenntnis des „Phosphormonosulfids”︁ (PS)x
Authors: Frehn Angelika , Keck Helmut , Kuchen Wilhelm 
Published: July 2007

New Results Concerning the “Phosphorus Monosulfide” (PS)xThe orange‐yellow solid of approximate composition (PS)x obtained by dehalogenation of P(S)Br3 with Mg proved to be a mixture of phosphorus sulfides e.g. P4S3, P4S4, P4S5, P4S7, and insoluble polymeric material. It is suggested that the latter contains a network of triply connected P atoms, many of which are substituted by groups. The conclusions are based on the results of analytical, mass‐spectrometric and 31P‐NMR‐spectroscopic findings.
Addukt eines fünfgliedrigen Trischwefeldistickstoffdioxid‐Rings an Titantetrachlorid
Authors: Roesky Herbert W. , Schimkowiak Jürgen , Schmidt Hans‐Georg , Noltemeyer Mathias , Sheldrick George M. 
Published: July 2007

Adduct of a Five‐Membered Trisulfurdinitrogen Dioxide Ring with Titanium TetrachlorideReaction of S6N4O4 with TiCl4 lead to [(S3N2O2)TiCl4]2 (2). Single crystals of 2 were obtained by recrystallization from liquid SO2. 2 forms chains of five‐membered S3N2O2 rings connected by Ti2Cl8 units. The S2N2 part of the five‐membered ring may be described as a 6‐π electron system.
Transition‐Metal‐Catalyzed Oxidations, 2. Titanium‐ or Zirconium‐Catalyzed Selective Dehydrogenation of Benzyl Alcohols to Aldehydes and Ketones with tert‐Butyl Hydroperoxide
Authors: Krohn Karsten , Khambabaee Keramall , Rieger Hagen 
Published: July 2007

AbstractPrimary and secondary benzyl alcohols are selectivity converted in high yields into the corresponding aldehydes or ketones using tert‐butyl hydroperoxide and catalytic amounts of titanium or (better) zirconium alcoholates. Aliphatic hydroxy groups, double bonds (except those in allylic position to hydroxy groups), and phenolic hydroxy groups (except those in ortho position to the benzylic alcohol) are not attacked.
Substituenteneffekte auf die C–C‐Bindungsstärke, 8. Standardbildungsenthalpien und Spannungsenthalpien von 1,1,2,2‐Tetraethylethylenglykol‐dimethylether und D,L‐1,2‐Dimethyl‐1,2‐diphenylethylenglykol‐dimethylether
Authors: Dogan Barbara , Beckhaus Hans‐Dieter , Birkhofer Hermann , Rüchardt Christoph 
Published: July 2007

Effects of Substituents on the Strength of C ‐ C Bonds, 81. ‐ Heats of Formation and Strain of 1,1,2,2‐Tetraethylethylene Glycol Dimethyl Ether and D,L.‐1,2‐Dimethyl‐l,2‐diphenylethylene Glycol Dimethyl EtherThe heats of combustion of the title compounds 1 and 2 were measured calorimetrically with the result (kcal mol ‐1, s. d. in parentheses) ΔH°c = − 1880.1 (± 0.6) and − 2373.3 (± 1.4). The heat of vaporisation of 1 ΔHv = 14.3 (± 0.3) and the heat of sublimation of 2 ΔHsub = 27.2 (± 0.5) were derived from their temperature dependance of the vapor pressure. The latter were determined between 30 and 80°C using a flow method. The resulting standard heats of formation ΔH°t(g) = −122.4 (± 0.7) and −43.8 (±1.5) for 1 and 2 correspond to a strain enthalpy (s) of 15.9 and 8.0 kcal mol‐1, respectively. The steric strain of the dimethoxyethanes 1 and 2 is about one fourth lower than the strain of the corresponding dimethylethanes 3 and 4 bearing the same substituents. Thus, a methoxy group causes less steric stress than a methyl group.
1,5‐Sigmatrope Umlagerung von Diels‐Alder‐Addukten bei der Reaktion von Alkatrienphosphonaten mit Acetylencarbonsäureestern – Ein neuer Weg zur Synthese von Benzyl‐ und Phenylphosphonaten
Authors: Mondeshka Diana , Tancheva Chonka , Angelov Christo 
Published: July 2007

1,5‐Sigmatropic Rearrangements of Diels‐Alder Adducts in the Reaction of Alkatrienylphosphonates with Alkyl Acetylenecarboxylates ‐ A New Method for the Synthesis of Benzyl‐ and PhenylphosphonatesThe reaction of dialkyl (3‐methyl‐1,2,4‐pentatrienyl)‐ and dialky] (3‐methyl‐1‐vinyl‐1,2‐butadienyl)phosphonic acids 1a–d an 5a, b, respectively, with alkyl esters of the acetylenecarboxylic acids 2a–d proceeds via 1,5‐sigmatropic rearrangement and aromatization of the initially formed Diels‐Alder adducts. The reaction with the unsymmetrical dienophiles 2a, b occurs with preferred formation of the cycloadducts A, leading to the benzylphosphonates 3a–h. The above reaction constitutes a new method for the preparation of difficulty accessible derivatives of the benzyl‐ and phenylphosphonic acids. The aromatic structures of the obtained compounds 3a–h, 4a–f, and 6a–d were proved by their IR, mass, and 1H‐NMR spectra.
Synthese mittlerer und großer Ringe, XXVII. Chromatographische Enantiomerentrennung von 3,6‐Heptanophthalid – ein Beitrag zur Frage der absoluten Konfiguration von [n]Paracyclophancarbonsäuren
Authors: Tochtermann Werner , Olsson Gese , Mannschreck Albrecht , Stühler Georgine , Snatzke Günther 
Published: July 2007

Synthesis of Medium and Large Rings, XXVII1. ‐ Chromatographic Separation of the Enantiomeric 3.6‐Heptanophthalides. ‐ A Contribution to the Problem of the Absolute Configuration of [nJ Paracyclophanecarboxylic AcidsThe partial chromatographic separation of the racemic title compound 1 (ee = 40%) was achieved on triacetylcellulose with ethanol using a recycling technique. Comparison of the CD spectra of (+)22365‐1 with (+)22365‐2 leads to the absolute configuration (P) for both compounds. This assignment is of interest in view of earlier configurational assignments for [n]paracyclophanecarboxylic acids.
α‐Methylene β‐S‐Thiolactones: Synthesis of a new Heterocycle by Sulfurization of an α‐Methylene β‐lactone and Its Structure
Authors: Adam Waldemar , Hasemann Ludiwig 
Published: July 2007

AbstractAn α‐methylene β‐S‐thiolactone, a new sulfur heterocycle, is prepared by sulfurization of the corresponding α‐methylene β‐lactone using Lawesson's reagent as sulfur source.
Silber(I)‐ und Kupfer(I)‐Komplexe von 1,6‐Cyclodecadiin und 1,7‐Cyclododecadiin
Authors: Gleiter Rolf , Karcher Michael , Kratz Detlef , Ziegler Manfred L. , Nuber Bernhard 
Published: July 2007

Silver(1) and Copper(1) Complexes of 1,6‐Cyclodecadiyne and 1,7‐CyclododecadiyneThe reactions of 1,6‐cyclodecadiyne (1), 1,7‐cyclododecadiyne (2), and 1,8‐cyclotetradecadiyne (3) with silver(I) triflate and copper(I) triflate yield colourless crystals: [C10H12·AgCF3SO3]n (4), [C10H12·CuCF3SO3]n(5), [C12H16·AgCF3SO3]n (6), [C12H16·CuCF3SO3]n (7), and [C14H20·AgCF3SO3]n (8). The spectroscopic data of 4–8 indicate a weak interaction between the triple bonds and the metal ion. In the crystal structure of 4 double‐strands of 1,6‐cyclodecadiyne rings in the chair conformation are coupled by Ag(CF3SO3)2Ag units to form a two‐dimensional network. The X‐ray analysis of single crystals of 6 and 7 reveals twelve‐membered rings that are connected by silver or copper ions, respectively. Each triflate ligand in 6 and 7 uses two of its oxygen atoms to coordinate two different metal centers. The result is a complex three‐dimensional network. In the case of the silver complex 8, the X‐ray analysis also exhibits a similar polymeric structure. Only slight differences of the structural parameters are observed on comparison of the free cyclic dialkyne and that bound to a metal in 4, 6, and 7. The conformation of the 10‐ or 12 membered rings in 1 and 2 are more or less identical to those in 4 or 6 and 7.
Darstellung der ersten Sulfin‐imide (Thion‐S‐imide) mit Perfluormethylgruppen unter Verwendung von Natrium‐hexamethyldisilazanid als schonendes Dehydrohalogenierungsreagenz
Authors: May Andrew , Roesky Herbert W. , Stalke Dietmar , Pauer Frank , Sheldrick George M. 
Published: July 2007

Preparation of the First Thione S‐Imides with Perfluoromethyl Groups by the Use of Sodium Hexamethyldisilazanide as a Mild Dehydrohalogenation ReagentFrom the reaction of the sulfenyl chloride 1 with the monosilylated amines 2a, b the sulfenamides 3a, b are obtained in good yields. 1,3‐Dehydrohalogenation of 3a, b with sodium hexamethyldisilazanide yields the thione S‐imides 5a, b. Imide 5a reacts with norbornene (6) to produce the isothiazolidine derivative 7. The structures of 5b and 7 are confirmed by X‐ray analyses.
Reaktionen an μ3‐verbrückenden Alkin‐Liganden auf Heterometallclustern
Authors: Bantel Harald , Powell Anne K. , Vahrenkamp Heinrich 
Published: July 2007

Reactions of μ3‐Bridging Alkyne Ligands on Heterometallic ClustersThe metal‐exchange methods to obtain alkyne‐bridged heterometallic clusters from RuCo2(CO)9(μ3‐RCC') (2) were improved, and the new clusters RuCoMoCp(CO)8(PhCCPh) (3c), RuCoNiCp(CO)6(MeCCPh) (5b), RuMoNiCp2(CO)5‐(MeCCMe) (6a), and HFeRuMoCp(CO)8(MeCCMe) (7a) were obtained thereby. Some of the alkyne‐bridged clusters were found to react with additional alkyne. One alkyne unit was incorporated in the products RuCoNiCp(CO)6(RCC')2 (9), two alkyne units were incorporated in the products Ru‐Co2(CO)7(RCC')3 (8). In a side reaction, butyne was trimerized to hexamethylbenzene. Radical anions of the clusters FeCo2(CO)9(RCC') (1) were formed by reduction with cobaltocene. The reaction of these radical anions with alkylating reagents was accompanied by cluster fragmentation and CO insertion converting the former alkyne ligand by acylation into the new trisubstituted oxoalkenyl ligand in the products FeCo(CO)6(μ‐CRCR'‐CR″O) (11). The constitutions of the cluster types 7, 9 and 11 were confirmed by crystal‐structure determinations.
Functionalized cyclopentadienyl ligands, III. Preparation of cobalt half‐sandwich complexes with intramolecular CC bond coordination
Authors: Okuda Jun , Zimmermann Karl Heinz 
Published: July 2007

AbstractThermolysis of [1‐(3‐butenyl)‐2,3,4,5‐tetramethylcyclopentadienyl]carbonyldiiodocobalt, (η5‐C5Me4CH2CH2CHCH2)‐Co(CO)I2 (2), in boiling octane affords the dimeric diiodide [(η5‐C5Me4CH2CH2CHCH2)‐COI2]2 (3) without any interference of the 3‐butenyl chain with the cobalt center. 2 reacts with various two‐electron ligands L (LP(OMe)3, P(OPh)3, PPh3, PMe3, PMe2Ph, tBuNC] to give a series of cobalt(III) complexes of the general formulae (η5‐C5Me4CH2CH2CHCH2)‐Co(L)I2 (4–9). Sodium amalgam reduction of these “open‐chain” complexes 4–9 yields novel cobalt(1) complexes containing an intramolecularly coordinated CC bond (η5:η2‐C5Me4CH2CH2CHCH2)‐Co(L). For LCO (12), P(OMe)3 (13), and P(OPh)3 (14) low‐melting crystals are isolated and fully characterized by analytical and spectroscopic methods.
Kohlenwasserstoffverbrückte Komplexe, XVII. Darstellung und Kristallstruktur des Acyl‐verbrückten Komplexes (OC)3Fe{μ‐η1:η1‐C[CH2CH2Re(CO)5]O}2Fe(CO)3
Authors: Breimair Josef , Robl Christian , Beck Wolfgang 
Published: July 2007

Hydrocarbon‐Bridged Complexes, XVII1) – Synthesis and Crystal Structure of the Acyl‐Bridged Complex The addition of [Fe2(CO)8]2⊕ to [(OC)5Re(C2H4)]⊕ gives the diacyl‐bridged title complex 1 which was structurally determined by X‐ray diffraction.
Counterattack reagent bis(trimethylsilyl)acetamide in the disilylation of diols
Authors: Hwu Jih Ru , Anderson Denise A. , Wang Naelong , Buchner Meredith M. , Gani Paul , Tsay Shwu‐Chen 
Published: July 2007

AbstractThe counterattack method was applied to the disilylation of diols. Treatment of various diols with 0.3 or 1.1 equivalents of potassium hydride and 1.1 equivalents of bis(trimethylsilyl)‐acetamide in THF gave the corresponding disilyl ethers in good to excellent yields (60–95%). The diols may contain other functionalities, such as amide, amine, ether, and thioether. The diols used in the disilylation were 2a–14a. The newly developed disilylation proceeded in one flask by a sequential deprotonation‐silylation‐deprotonation‐silylation pathway. This disilylation also represents an example of a “tandem double‐counterattack process”. Bis(trimethylsilyl)‐acetamide acted as a counterattack reagent; it provided two Me3Si groups to diols and produced amides as bases.
Thermolyse von 5‐Alkyliden‐1,4‐dihydro‐5H‐tetrazolen
Authors: Quast Helmut , Bieber Lothar , Regnat Dieter 
Published: July 2007

Thermolysis of 5‐Alkylidene‐1,4‐dihydro‐5H tetrazolesIn benzene solution at 100°C, the isopropylidenedihydrotetrazole 1 a decomposes mainly (80%) into molecular nitrogen and the aziridinimines (E)‐ and (Z)‐2a which are thermally unstable and afford methyl isocyanide and the imine 3a. In addition, the novel spirocyclic tetrahydropyrimidine 7a is formed (18% yield) in a [4 + 2] cycloaddition of 1a and the hypothetical intermediate 1,3‐diazabutadiene 19a generated from 1a through a [1,4] hydrogen shift and loss of molecular nitrogen. The thermolysis of the neopentylidenedihydrotetrazole 1b at 100°C is more complex. Only small amounts of the aziridinimines (E)‐ and (Z)‐2b and their decomposition products 3b and methyl isocyanide are observed. A major product is the spirocyclic tetrahydropyrimidine 7b which exhibits moderate thermal stability. Slow thermolysis of 7b affords the tetrahydropyrimidinimine 8b and methyl azide. The latter reacts with 1b in a [3 + 2] cycloaddition furnishing the spiro compound 5b which partially decomposes into the amino‐1,2,3‐triazole 16, thus regenerating methyl azide. This catalyzed isomerization 1b → 16 which is initiated through the thermal [3 + 2] cycloreversion of 7b involves a total of 19% of 1b. The structures of the products are elucidated by means of mass spectra and high‐field NMR spectra. The mechanism of formation of the 1,3‐diazabutadienes 19 from 1 is discussed.
A macrocyclic 2,19‐dioxo[3.3](3,3′) azobenzolophane by transition‐metal carbonyl complex‐mediated CO insertion and cyclization
Authors: Schmiegel Jürgen , Grützmacher Hans‐Friedrich 
Published: July 2007

Abstract2,19‐Dioxo[3.3](3,3′)azobenzolophane (5) has been obtained in a total yield of 18% by way of CO insertion and cyclization of 1,2‐bis[3‐(bromomethyl)phenyl]‐4,4‐dimethyl‐3,5‐pyrazoli‐dinedione (1) using Co2(CO)8 in acetonitrile followed by the removal of the N‐protecting 4,4‐dimethylmalonyl groups. 5 is obtained predominantly as the trans / trans isomer 5a and can be isomerized by irradiation with λ=369 nm to a mixture of nearly equal amounts of the trans / trans, cis / trans, and cis / cis isomers 5a, 5b and 5c. The thermal isomerization back to 5a is slow but fast upon irradiation with λ=443 nm.
Intramolekulare Donator‐Akzeptorwechselwirkungen in λ4P(V)‐Verbindungen Phosphor(V)‐Derivate des N,N,N′‐Trimethylethylendiamins
Authors: Becker Wilfried , Jones Peter G. , Schomburg Dietmar , Schmutzler Reinhard 
Published: July 2007

Intramolecular Donor‐Acceptor Interactions in λ4P(V) Compounds. — Phosphorus(V) Derivatives of N,N,N′‐Trimethyl‐ethylenediamineThe chlorophosphino derivative of N,N,N′‐trimethylethyl‐enediamine Me2NCH2CH2(Me)NP(Cl)Me (1) and the 2‐(diethylamino)‐λ3‐phospholidinium salt [Me2magnified imageNEt2]+ Cl− (5) have been allowed to react with several oxidizing agents. Reaction of 1 with dimethyl sulfoxide furnishes the phosphonamidic chloride Me2NCH2CH2(Me)NP(O)(Cl)Me (3) while with elemental sulfur the phosphonamidothioic chloride Me2NCH2CH2(Me)NP(S)(Cl)Me (2) is obtained. The reaction of 2 with sodium tetraphenylborate furnished the 1,1,2,3‐tetramethyl‐1,3,2‐λ4‐diazaphospholidinium tetraphenylborate [Me2magnified image(S)Me]+ [BPh4]− (4). The reaction of 5 with phenyl azide, followed by sodium tetraphenylborate led to 2‐(diethylamino)‐2‐(phenylimino)‐1,3,2λ4‐diazaphospholidinium tetraphenylborate [Me2magnified image(NPh)NEt2]+ [BPh4]−1 (7). The methoxy‐λ3‐diazaphospholidinium salt [Me2magnified imageOMe]+ [BPh4]− (6) does not react with phenyl azide to produce the 2‐methoxy‐2‐(phenylimino)‐1,3,2λ4‐diaza‐phospholidinium salt analogous to 7; instead its rearrangement product, the dimeric 1,3,2λ4,4λ4‐diazadiphosphetidine tetraphenylborate [Me3NCH2CH2(Me)NP(O)NPh]2[BPh4]− (8), is isolated in low yield. Singlecrystal X‐ray structure determinations of 4 and 8 are described.
Übergangsmetall‐substituierte Diphosphene, XIX. Zur Reaktivität von Disilylphosphido‐Eisenkomplexen gegenüber 2,4,6‐(CF3)3C6H2PCl2und 2,6‐(CF3)2C6H3PCl2— Diphosphenylkomplexe mit Fluorarylsubstituenten
Authors: Weber Lothar , Schumann Hans , Boese Roland 
Published: July 2007

Transition‐Metal‐Substituted Diphosphenes. XIX. ‐ On the Reactivity of Disilylphosphido Iron Complexes towards 2,4.6‐(CF3)3C6H2PCl2and 2.6‐(CF3)2C6H3PCl2. Diphosphenyl Complexes with Fluoroaryl Substituents(η5‐C5Me5)(CO)2FeP(SiMe3)2(2a) and (η5‐C5H5)(CO)(PPh3)‐FeP(SiMe3)2(2c) react with ArylPCl2[3a: Aryl  2,4,6‐(CF)3‐C6H2;b: Aryl  2,6‐(CF)2C6H3] to yield the thermolabile diphosphenyl complexes (η5‐C5Me5)(CO)2FePP‐Aryl (4a,b) and (η5‐C5H5)(CO)(PPh3)FePP‐Aryl (4c,d), respectively. The isolation of the pure compounds4a‐dfailed. They are, however, intercepted as their (CO)5Cr adducts5a–dby treatment with [(Z)‐cyclooctene]Cr(CO)5‐ Complex (η5C5Me5)(CO)2FeP[Cr(CO)5] P‐C6H2(CF3)3‐(2,4,6) (5a) is characterized by single‐crystal X‐ray diffraction analysis.
[(Dimethylphenylsilyl)tetramethylcyclopentadienyl]thallium(I) und [(Benzyldimethylsilyl)tetramethylcyclopentadienyl]thallium(I) — polymere Metallorganyle mit Kettenstruktur
Authors: Schumann Herbert , Kucht Homa , Dietrich Andreas , Esser Lothar 
Published: July 2007

[(Dimethylphenylsilyl)tetramethylcyclopentadienyl]thallium(I) and [(Benzyldimethylsilyl)tetramethylcyclopentadienyl]‐thallium(1) ‐ Polymeric Organometallic Compounds with Chain Structure(Dimethylphenylsilyl)tetramethylcyclopentadiene (2) and (benzyldimethylsilyl)tetramethylcyclopentadiene (3) were prepared from (tetramethylcyclopentadienyl)lithium (1) and chlorodimethylphenylsilane or benzylchlorodimethylsilane, respectively. 2 and 3 react with TIOC2H5 (4) to form [C5Me4(SiMe2Ph))TI (5) and [C5Me4(SiMe2CH2Ph)]TI (6), respectively. The 1H‐ and 13C‐NMR spectra of the new compounds as well as the single‐crystal X‐ray structural analyses of the polymeric metallocenes 5 and 6 are described and discussed.
Trisilazan‐1‐yl‐cyclodisilazane — Expansionen, Kontraktionen und Ringkopplungen
Authors: Dippel Kerstin , Klingebiel Uwe 
Published: July 2007

Trisilazan‐1‐yl‐cyclodisilazanes — Expansions, Contractions. and Ring CouplingsLithiated trisilazan‐1‐yl‐cyclodisilazanes react in different ways. The lithium derivatives of 2 and 3 react with fluorosilanes with substitution to give 4 and 5. In the reaction of dilithiated 3 with chlorotrimethylsilane the cyclotrisilazane 6 is formed by ring expansion. In the same reaction the symmetrically substituted four‐membered ring 7 is obtained, which is formed by ring contraction of the anion of 6. The silyl‐bridged ring systems 8–11 are obtained on reaction of dilithiated 3 with fluorosilanes and F2BN(SiMe3)2. An analogous silylbridged four‐membered ring system 12 is formed in the reaction of the eight‐membered ring anion with F3SiN(SiMe3)2.
Chirale Homoenolat‐Äquivalente, IV. Kristallstruktur einer chiralen 1‐Aminoallyllithium‐Verbindung: dimeres, intramolekular chelatisiertes (3S)‐3‐Lithio‐1‐[(S)‐2‐(methoxymethyl)pyrrolidino]‐1,3‐diphenylpropen
Authors: Ahlbrecht Hubertus , Boche Gernot , Harms Klaus , Marsch Michael , Sommer Horst 
Published: July 2007

Chiral Homoenolate Equivalents, IV. — Crystal Structure of a Chiral 1‐Aminoallyllithium Compound: Dimeric, Intra‐molecularly Chelated (3S)‐3‐Lithio‐1‐[(S)‐2‐(methoxymethyl)pyrrolidino]‐1,3‐diphenylpropeneThe chiral title compound crystallizes from toluene as a dimer. Two molecules toluene cocrystallize outside the aggregate. The 1‐aminoallyl group is nearly planar. Both exo‐placed phenyl groups and the endo‐placed pyrrolidine group are twisted against the allylic plane. The nitrogen atom is pyramidal, the lone pair is directed to the allyl group (in‐conformer). The bond angle C1‐C2‐C3 is widened, and the bond distances C1‐C2 and C2‐C3 alternate slightly. This is indicative of a strongly delocalized 3‐metallated enamine structure. The lithium atom of one monomer unit is bound to the C3 atom and chelated intramolecularly by the nitrogen and oxygen atoms. Therefore it is placed on the Si side of the allylic plane. Its free coordination site is occupied by the benzyl group of the second monomer unit. The dimer can hence be regarded as being an allyl‐ as well as a benzyllithium compound at the same time. MNDO calculations reproduce the results of the X‐ray structure determination satisfactorily and allow some insight into possible structures in solution.
Zum Mechanismus der Cyclopropan‐„Walk”︁‐Umlagerung: Synthese und Eigenschaften von 2‐Diazopropan‐Aren‐Addukten; eine regiospezifische N2‐Eliminierung
Authors: Klärner Frank‐Gerrit , Glock Volker , Hemmes Jan‐Luiken 
Published: July 2007

Mechanism of the Cyclopropane “Walk” Rearrangement: Syntheses and Properties of 2‐Diazopropane ‐ Arene Adducts; a Regiospecific N2 EliminationThe synthesis and the thermal and photochemical behavior of 2‐diazopropane adducts of toluene 1a, m‐xylene 1b,c, and Dewar benzene 2a,b are reported. At 60°C the thermal N2 elimination of the specifically deuterated compound 1c proceeds regiospecifically leading to 1,7,7‐trimethyl‐5‐(trideuteriomethyl)‐1,3,5‐cycloheptatriene (12c), whereas the photolysis of 1c sensitized by benzophenone yields both regioisomeric cycloheptatrienes 12c and 13c in a 51:49 ratio. This finding excludes the symmetrical diradical 3c as an intermediate in the thermal N2 elimination of 1c and suggests a novel pericyclic process for it. The formation of both regioisomeric cycloheptatrienes 25b and 25c in a 74:26 ratio in the thermolysis of the diazopropane‐tetradeuterio Dewar benzene adduct 2b indicates that in this case a multi‐step N2 elimination passing through the diradical intermediate 3e competes with the concerted process. According to force‐field calculations the course of the N2 elimination in 1a‐e might be controlled by the conformational equilibrium A⇆B