bluuebunny/crossref_metadata_2025_split huggingface dataset:
Eine einfache Synthese von dimetallischen Zirconium/Aluminium‐Verbindungen mit planar‐tetrakoordiniertem Kohlenstoff
Authors: Erker Gerhard , Albrecht Markus , Werner Stefan , Nolte Matthias , Krüger Carl 
Published: July 2007

A Simple Synthesis of Dimetallic Zirconium/Aluminium Compounds Containing Planar‐Tetracoordinate Carbon(η2‐Alkyne)(trimethylphosphane)zirconium complexes [alkyne = cyclohexyne (3a) or diphenylacetylene (3b)] react with diisobutylaluminium hydride at room temperature by PMe3 cleavage and addition of HAl(isobutyl)2 to the in situ‐generated (η2‐alkyne)ZrCp2 intermediate to give the dimetallic Zr,Al compounds 4. These thermodynamically stable complexes contain a planar‐tetracoordinate carbon center whose uncommon coordination geometry is stabilized by a combination of the s̀‐donor interaction with both electropositive metals and the π‐conjugation of the ZrC  C moiety.
Studien zur C–H‐Aktivierung, VIII, Hydrido(vinyl)rhodium(III)‐Komplexe aus [RhCl(PiPr3)2] und Olefinen
Authors: Dirnberger Thomas , Werner Helmut 
Published: July 2007

Studies on C–H Activation, VIII[1]. – Hydrido(vinyl)rhodium(III) Complexes from [RhCl(PiPr3)2] and OlefinsThe reaction of [RhCl(PiPr3)2]n (1) with methyl vinyl ketone leads to the formation of the olefin complex trans‐[RhCl(CH2 = CHC(O)Me)(PiPr3)2] (2) which rearranges at ambient temperatures to give the hydrido(vinyl)rhodium(III) isomer magnified image (3). From 1 and the α,β‐unsaturated ketones RCH = CHC(O)Me (R = MeO, Me, Ph) the corresponding hydrido(vinyl) derivatives magnified imagemagnified image (5–7) are directly obtained. Treatment of 1 with acroleine CH2 = CHC(O)H gives the olefin complex trans‐[RhCl(CH2 = CHC(O)H)(PiPr3)2] (8) that does not react by C–H activation but by elimination of ethylene to form the carbonyl compound trans‐[RhCl(CO)(PiPr3)2] (4). The reactions of 1 with CH2 = CHCO2Me, (E)‐ and (Z)‐CH(CO2Me) = CH(CO2Me) afford monomeric (10, 12) or dimeric (14) olefin‐rhodium(I) compounds from which 12 is transformed by UV irradiation to give the hydrido(vinyl) isomer magnified imagemagnified image (16). Structurally related hydrido(vinyl)rhodium(III) complexes magnified imagemagnified image (17) and magnified image(PiPr3)2] (20, 21) are obtained either directly from 1 and the α,β‐unsaturated carbonyl compound or in two steps via the olefinrhodium(I) precursor. The IR and NMR data of the hydrido(vinyl) compounds prove unambiguously that the vinyl ligand is coordinated by the carbon and the carbonyl oxygen atom.
Phosphanalkylene, 52. Umsetzung von [1‐(Trimethylsilyl)alkyliden]triphenylphosphoranen mit Kohlendioxid und Folgereaktionen
Authors: Bestmann Hans Jürgen , Dostalek Roman , Zimmermann Reiner 
Published: July 2007

Phosphane Alkylenes, 52[1]. – Reactions of [1‐(Trimethylsilyl)alkylidene]triphenylphosphoranes with Carbon Dioxide2‐(Triphenylphosphoranylidene) carboxylic acid esters 6 have been synthesized from 1‐(trimethylsilylalkylidene)phosphoranes 4 and carbon dioxide. The reactions of the ylides 6 with aldehydes 9 lead to α,β‐unsaturated silyl esters 10 in good yields and with high (E) stereoselectivity. Thermolysis of 6d affords (oxovinylidene)triphenylphosphorane (7).
Reaktionen von Komplexliganden, LI. Synthese und Reaktionen stabiler (Carben)tetracarbonyl‐Chelatkomplexe des Molybdäns
Authors: Dötz Karl Heinz , Larbig Harald , Harms Klaus 
Published: July 2007

Reactions of Complex Ligands, LI[1]. – Synthesis and Reactions of Stable (Carbene)tetracarbonyl Chelate Complexes of MolybdenumThe stable (carbene‐C,O, ‐C,N, and ‐C,S)tetracarbonyl chelate complexes of molybdenum 2b–2c have been obtained by mild decarbonylation of their corresponding pentacarbonyl precursors 1b–1c. The chelate complexes have been characterized by elemental analyses and spectroscopic data. In addition, the structure of C,N chelate 2c has been confirmed by X‐ray analysis. In contrast to its C,N and C,S analogues, the C,O chelate complex 2a undergoes ring opening at temperatures as low as ‐40°C upon addition of triphenylphosphane. At 20°C the phosphane‐substituted chelate complex 4a is obtained. C,N and C,S chelate complexes require higher temperatures for the reaction to give similar fac‐tricarbonyl complexes 4b–4c.
NbTe4I und TaTe4I, zwei neue Tellurid‐Iodide mit Kettenstruktur
Authors: Tremel Wolfgang 
Published: July 2007

NbTe4I and TaTe4I, Two New Telluride Iodides with Chain StructureNbTe4I and TaTe4I, are synthesized in almost quantitative yields by reaction of the elements in the appropriate ratio at 540°C and 480°C, respectively. The crystal structure determinations show that both structures are built up from quasi one‐dimensional Nb(Te2)2 and Ta(Te2)2 chains that are separated by isolated iodine atoms. The metal–metal distances within these chains are outside the metal–metal bonding range. Both compounds are formally described as (Nb5+)(Te22−)2(I−) and (Ta5+)(Te2−2)2(I−), and semiconducting properties must be assumed. Short Te‐I contacts between Te atoms of and I atoms between the chains indicate significant anion‐cation charge transfer.
Synthesis and Structure of a New Bis[(trimethylphosphan)titanocene] Complex with a Bridging C2 Unit
Authors: Binger Paul , Müller Patrik , Philipps Petra , Gabor Barbara , Mynott Richard , Herrmann Albert T. , Langhauser Franz , Krüger Carl 
Published: July 2007

AbstractBis(trimethylphosphane)titanocene (1) reacts with 2‐methylene‐1,1‐diphenylcyclopropane (2) to give red crystalline (η2‐2‐methylene‐1,1‐diphenylcyclopropane)(trimethylphosphane)titanocene (3). In solution complex 3 degrades smoothly to form the new Cp2Ti(PMe3) – C2 – Ti(PMe3)Cp2 complex 4, the crystal structure of which has been elucidated by an X‐ray analysis.
Beiträge zur Chemie des Bors, 212. Azaphosphoniaborataborolidine und ihre Thermolyse zu Diazaphosphadiborinanen
Authors: Ederer Bernd , Ederle Henry , Nöth Heinrich 
Published: July 2007

Contributions to the Chemistry of Boron, 212[1]. – Azaphosphoniaborataborolidines and their Thermolysis to DiazaphosphadiborinanesMe3SiN = PN(SiMe3)2 (1) adds Lewis‐acidic diborylmethanes CH2[B(Cl)X]2 (6a–d, X = Cl, Me, Ph, Mes) to yield the five‐membered azaphosphoniaborataborolidines 9a–d by haloboration and formation of an intramolecular coordinative phosphorus boron bond. However, the less Lewis‐acidic diborylmethane CH2[B(Cl)NMe2]2 does not react with 1. NMR studies on 9 exhibit conformational dependence of the ring system on the bulkiness of X, suggesting a decreasingly folded structure for X = Mes > Ph > Me and a planar ring for X = Cl, the latter proven by an X‐ray structure analysis. 9 a, b rearrange their ring framework on heating with elimination of Me3SiCl to give diazaphosphadiborinanes 7. Compound 7b shows the typical reactions of a diamino(chloro)phosphane: oxidation by S8 yields the corresponding phosphane sulfide 17 while AlCl3 abstracts a chloride ion with formation of a phosphenium tetrachloroaluminate 13. In the reaction of 7b with BBr3 halogene exchange (to 16) dominates, while a phosphane borane adducts (15) is formed in a side reaction only.
Reaktive 3,4‐disubstituierte Derivate des 1,6‐Methano[10]annulens und ihr Synthesepotential
Authors: Neidlein Richard , Schröder Günter 
Published: July 2007

Reactive 3,4‐Disubstituted Derivatives of 1,6‐Methano[10]annulene and their Synthetic PossibilitiesEthyl 4‐bromo‐1,6‐methano[10]annulene‐3‐carboxylate (4) is synthesized in three steps from cycloheptatriene‐1,6‐dicarbaldehyde 1. The key step of this conversion is a highly selective monoolefination of 1. The synthetic possibilities of 4 are discussed.
Flexible molecules with defined shape, II. Control of n‐heptane conformer populations by methyl substitution or ring annulation
Authors: Hoffmann Reinhard W. , Sander Thomas , Brumm Martin 
Published: July 2007

AbstractThe conformations of a flexible n‐heptane chain are considered. Six‐membered ring annulation at the inner bonds leads to 1,3‐disubstituted cyclohexanes, at the outer bonds to dicyclohexylmethane derivatives. Force‐field calculations show that these molecules maintain the conformational mobility of the heptane chain to a large degree, yet some populate one particular conformer to more than 80% (up to 99% in the case of 17). The predominant conformers of the molecules described here allow to represent each of the regular (diamond lattice type) conformations of a heptane chain. Moreover, for the open‐chain heptane derivatives the effect of methyl substitution on the conformational preferences has been examined. Finally, the adamantane derivative 32 has been identified in giving the heptane chain a 93% preference for the tg + g + t‐conformation.
Unsymmetrical phthalocyanines with a single macrocyclic substituent
Authors: Musluoglu Emel , Gürek Aysegül , Ahsen Vefa , Gül Ahmet , Bekaroǧlu özer 
Published: July 2007

AbstractUnsymmetrical phthalocanines (5–7) with a single macrocyclic substituent are synthesized by the reaction of the boron complex of phthalonitrile (1) with the iminoisoindoline derivatives 2–4 of macrocyclic compounds, i.e. 15‐crown‐5, monoaza‐15‐crown‐5, and tetraazacyclotetradecane. The monomacrocycle‐substituted phthalocyanines are less soluble than the tetra‐substituted one.
Neue Perrhenate und Aminorheniumtrioxide mit Elementen der 14. und 15. Gruppe des Periodensystems
Authors: Wirringa Uwe , Roesky Herbert W. , Schmidt Hans‐Georg , Noltemeyer Mathias 
Published: July 2007

AbstractNew Perrhenates and Aminorhenium Trioxides with Elements of Group 14. and 15. of the Periodic SystemNew perrhenates have been prepared by reaction of Re2O7 with triphenylstibin oxide and di‐n‐butyltin oxide, respectively. The single‐crystal X‐ray structure of Ph3Sb(OReO3)2 (1) is reported. The reaction of Ph3SbO and nBu2SnO with Re2O7 in 1:2 molar ratio gives (O3ReOSbPh3)2O (2) and [O3ReOSn‐(nBu)2]2O (3), respectively. A trimethylstannyl‐substituted aminorhenium trioxide (Me3Sn)2NReO3 (4) has been prepared by reaction of Me3SiOReO3 and N(SnMe3)3.
Organometall‐Imide – höhervalente Derivate der d‐Metall‐Säuren, 3. Synthese und Reaktionen von (Pentamethylcyclopentadienyl)(imido)‐Komplexen des Molybdäns und Wolframs und eine effiziente Strategie zur Synthese der Organometallate NBu4[Cp*MO3] (M = Mo, W)
Authors: Sundermeyer Jörg , Radius Udo , Burschka Christian 
Published: July 2007

AbstractOrganometallic Imido Complexes – Highervalent Derivatives of the d‐Metal Acids, 3[4b]. – Synthesis and Reactions of Pentamethylcyclopentadienyl Imido Complexes of Molybdenum and Tungsten and an Efficient Strategy for the Synthesis of the Organometallates NBu4[Cp*MO3] (M = Mo, W)A convenient and new entry into the chemistry of highvalent pentamethylcyclopentadienyl halfsandwich complexes of molybdenum and tungsten is described. The reaction of Mo‐(NtBu)2Cl2 or W(NtBu)2Cl2(py)2 with Cp*Li (Cp* = η5‐C5Me5) provides a high‐yield route to new complexes Cp*Mo‐(NtBu)2Cl (1a) and Cp*W(NtBu)2Cl (1b) which are converted into a variety of diimido, monoimido, and oxo derivatives. Treatment of 1a,b with MeLi yields the highly volatile methyl derivatives Cp*Mo(NtBu)2Me (2a) and Cp*W(NtBu)2Me (2b), while protolysis of 1a,b with an excess of HCl gas leads to selective cleavage of only one imido function with formation of Cp*Mo(NtBu)Cl3 (3a) and Cp*W(NtBu)Cl3 (3b). In contrast, protolysis of 1a,b with aqueous HCl provides a high‐yield route to the well‐known organometallic oxides [Cp*MoO2]‐(μ‐O) (4a) and [Cp*WO2](μ‐O) (4b). These two key compounds are easily converted into the organomolybdate and organotungstate salts NBu4[Cp*MoO3] (5a) and NBu4[Cp*WO3] (5b) by cleavage of the M–O–M bridge with NBu4[OH]. The X‐ray structure of 3a is reported.
Trägerfixierte Organometallkomplexe, III. Polysiloxan‐gebundene (Ether‐phosphan)ruthenium(II)‐Komplexe und ihre CP‐MAS‐NMR‐spektroskopische Charakterisierung
Authors: Lindner Ekkehard , Kemmler Martin , Mayer Hermann August 
Published: July 2007

AbstractCarrier‐Bound Organometallic Complexes, III[1]. – Polysiloxane‐Bound (Ether‐phosphane)ruthenium(II) Complexes and Their CP‐MAS NMR‐Spectroscopic CharacterizationThe reaction of the functionalized ether‐phosphane ligand CH3O(CH2)2P(Ph)(CH2)3Si(OMe)3 (1c) with Cl2Ru(PPh3)3 (2) and HRuCl(CO)(PPh3)3 (3) results in the formation of the mono‐chelated (ether‐phosphane)ruthenium(II) complex Cl2Ru(P∼O)2(P∼O) (4c) and the hydride HRuCl(CO)(P∼O)3 (5c) (P∼O: η1‐P‐coordinated; P∼O: η2‐O∼P‐coordinated). Compounds 4c and 5c are polycondensated to the corresponding polysiloxane‐bound complexes 4c′ and 5c′. 31P‐chemical shifts of the immobilized species 4c′ and 5c′ in the solid‐state CP‐MAS NMR spectra are compared with those of the 31P{1H}‐NMR spectra of monomeric complexes 4b, c and 5b, c with the ligands CH3O(CH2)2P(Ph)(CH2)3SiMe3 (1b) and 1c in solution. No change in the structure between the monomeric and polymeric species could be observed. According to 29Si CP‐MAS NMR‐spectroscopic investigations the polysiloxane chains are connected by ruthenium complexes to a network with favourable properties. The chelated polysiloxane‐bound red complex 4c′ adds CO in the solid state to give quantitatively yellow all‐trans‐Cl2Ru(CO)2(P∼O)2 (6c′). In the presence of carbon monoxide there is an equilibrium between 5c′ and HRuCl(CO)2(P∼O)2 (7c′) which was also found in solution for 5b, c and 7b, c. The reactions indicate that the chemistry of polysiloxane‐bound ether‐phosphane complexes can well be compared with the chemistry in solution. 31P CP‐MAS NMR spectra of the complexes 4c′ and 5c′ are strongly dominated by a chemical shift anisotropy which shows a fingerprint pattern both for monomeric crystalline complexes 4a, 5a [containing ligand Ph2P(CH2)2OCH3 (1a)] and polysiloxane‐bound phosphane complexes 4c′ and 5c′.
Transition‐Metal‐Catalyzed Oxidations, 5. Oxygenation of ortho‐Alkylated α‐ and ß‐Naphthols to α‐Ketols
Authors: Krohn Karsten , Brüggmann Kai , Döring Detlev , Jones Peter G. 
Published: July 2007

AbstractThe α‐ and ß‐naphthols 7a–7d, 8a and 8b are converted into the corresponding α‐ketols 9a–9c, 10a, 10b and 10d with concomitant dearomatization of ring A and partial shift of the alkyl group by reaction with tert‐butyl hydroperoxide in the presence of Ti(OiPr)4, Zr(acac)2 or [MoO(O2)2] py HMPT.
Base‐Induced Chemiluminescence of Acetoxy‐Substituted Benzofuran Dioxetanes by an Intramolecular Electron Transfer (CIEEL) Mechanism
Authors: Adam Waldemar , Schulz Manfred H. 
Published: July 2007

AbstractTetraphenylporphine‐sensitized photooxygenation of acetoxy‐substituted benzofuran derivatives 2 afforded the corresponding benzofuran dioxetanes 3. The base‐induced decomposition of these dioxetanes was studied and shown to involve an intramolecular CIEEL emission. The CIEEL chemiluminescence quantum yields were measured. The dioxetane 3e, in which the electron donor is located meta to the dioxetane site, exhibits the highest chemiluminescence of all derivatives investigated.
Photochemistry of N‐Phthaloyl α‐Amino Acid Esters: A New Approach to β,γ‐Unsaturated α‐Amino Acid, Dihydrobenzazepinedione, and Pyrrolizidinone Derivatives
Authors: Griesbeck Axel G. , Mauder Harald , Müller Ingrid 
Published: July 2007

AbstractThe N‐phthaloyl‐α‐amino acid methyl esters of 2‐aminobutyric acid (2a), valine (2b), norvaline (2c), tert‐leucine (2d), isoleucine (2e), allo‐isoleucine (2f), leucine (2g), methionine (2h), alanine (2i), and phenylalanine (2k) were synthesized in enantiomerically pure form via the N‐phthaloyl‐α‐amino acids (1a–k), and their photochemistry was studied. Except 2i and 2k, which proved to be photostable, all compounds were converted into three types of products, depending on the substitution pattern: a) isomerization products (derivatives of β,γ‐unsaturated α‐amino acids) 3a, b, c, and e, b) ring expansion products (benzazepinedione esters) 4a and c, and c) cyclization products (5d from the tert‐leucine derivative 2d). High diastereoselectivities (d.r. > 95:5) were observed for all reactions except the transformations of the 2‐aminobutyric acid derivative 2a. The absolute configuration of the α‐stereogenic center was retained during photolysis, as proven for the isode‐hydrovaline (type a product) 3b. PCC oxidation (to give 7b) and hydrogenation afforded 2b with an optical rotation comparable to the starting material. Treatment of 3b with an acid or a base led to epimerization (3b′) or isomerization of the C = C bond (6b), respectively. The diastereomeric dihydrobenz‐azepinedione esters 4a, b were formed with d.r. = 33:67 (cis: trans) and in 60% yield during photolysis of 2a. The isoleucine derivative 2e, however, was converted into the cis isomer 4a with high diastereoselectivity (d.r. >95:5), whereas the corresponding allo substrate 2f was only converted into the trans‐isomer 4b. Ethylene was extruded during irradiation of the latter substrates and during irradiation of the norvaline derivative 2c, whereas propene extrusion from the leucine derivative 2g led to the formation of the unsubstituted type b product 4c. The methionine derivative 1h was the only N‐phthaloylamino acid which did not show photodecarboxylation, instead two ζ‐hydrogen abstraction products were formed: the hydroxy acid 9h and the tetracyclic lactone 10h. The methionine ester 2h was only converted into the ring expansion products 11h, h′ presumably by a photo electron transfer step. The chronology of the double hydrogen transfer reaction (γ‐ followed by δ‐H abstraction, leading to type a products) was determined by using the deuterium labeled compound (±)[3–D1]‐2b.
Substituenteneffekte auf die Struktur von Spiropentan
Authors: Irngartinger Hermann , Gries Stefan , Klaus Philip , Gleiter Rolf 
Published: July 2007

AbstractSubstituent Effects on the Structure of SpiropentaneIn order to investigate the influence of substituents on the bond lengths of the spiropentane framework, the molecular structures of the spiropentane derivates 1–7 have been determined by X‐ray analysis. The π acceptor substituents (CO, CO2R, Ph) shorten the distal bond of the substituted three‐membered ring by δ = ‐0.02 Å. The vicinal bonds are lengthened by δ/2. The π donor‐s̀ acceptor groups have the opposite effect [δ(Cl2) = 0.019, δ(F2) = 0.056 Å]. The influence of several substituents is additive. The longer peripheral bond [1.530(14) Å] is varied to the same degree as the shorter central bond [1.482(9) Å]. The second three‐membered ring of the spiropentane system is not affected. These results are explained qualitatively by considering the valence MO′s of a distorted spiropentane. Quantum chemical calculations using a 3–21 G basis set confirm this picture.
Substituenteneinflüsse auf die Struktur von 1‐Azaspiropent‐1‐en
Authors: Irngartinger Hermann , Gries Stefan 
Published: July 2007

AbstractSubstituent Effects on the Structure of 1‐Azaspiropent‐1‐eneLow‐temperature (199 K) X‐ray structure analyses of the azaspiropentene 1 and its dimer 2 have been undertaken. The peripheral bonds of 1 (C–C 1.544, C=N 1.278 Å) are elongated because of steric strain and conjugation with the phenyl ring (for C=N). The distal bond (C–C 1.485 Å) in the three‐membered ring of 2 is shortened by the substituent effects of the N=C and C=N groups.
Verklammerte Tolane
Authors: Bauer Martin , Nieger Martin , Vögtle Fritz 
Published: July 2007

AbstractThe tolanophanes 1, 2 and 3 are prepared by Wittig cyclization reactions. The corresponding “stilbenophanes” 21 and 13 are also isolated. The X‐ray structure analysis of 1 revealed a bending of the acetylene triple bond by 11 degrees. Attempts to aim at the “superphane” 23 by reaction with transition metal complex catalysts were unsuccessful; reaction with phenyl‐carbene lead to the cyclopropenyl cation 22.
Synthesis of 1‐Substituted 1,2,3,4‐Tetrahydroisoquinolines from Enamino Ketones
Authors: Tietze Lutz F. , Schimpf Ralph , Wichmann Jürgen 
Published: July 2007

AbstractThe reaction of the N‐acylated enamino ketones 4a–d with trifluoroacetic acid, TMS triflate, or Lewis acids leads to the 6,7‐dimethoxy‐1,2,3,4‐tetrahydroisoquinolines 5a–d in 84 to 94% yield. The enamino ketones 4f–i can only be cyclized with trifluoromethanesulfonic acid to the 1,2,3,4‐tetrahydroisoquinolines 5f–i in 75–84% yield. For the synthesis of 5e from the enamino ketone 4e carrying the benzyloxycarbonyl group TMS triflate is the best mediator (93%). The trichloromethylcarbonyl group in 5 can easily be transformed into a methoxycarbonyl group by treatment with K2CO3 in methanol to give 6 in 83–90% yield.
Darstellung und Photochemie eines (Anthrylvinyl)thiophenfulgids
Authors: Effenberger Franz , Wonner Johann 
Published: July 2007

AbstractPreparation and Photochemistry of an Anthrylvinyl Thiophene FulgideThe base‐catalyzed reaction of isopropylidenesuccinate 2 with phenylthienylpropenone 1a does not give a Stobbe condensation to 3a but results in an 1,4‐addition to 7 which under the basic conditions reacts further to 8 by an intramolecular condensation. The (anthrylvinyl)thiophene fulgide 4c is obtained, however, from 3‐glyoxyloyl‐2,5‐dimethylthiophene hydrate (11) via the 2H‐pyran 14: Wittig olefination of 14 with the phosphonium salt 16 leads to the diester 3c which easily is converted to Z,E‐4c. – Irradiation of Z,E‐4c gives a mixture of all four possible E,Z isomers of 4c and the ring‐closed valence tautomers Z‐ and E‐17. All isomers could be separated and characterized. Compound 18, formed irreversibly in a thermally‐induced reaction, is enriched during irradiation.
Photolyse von 3‐Methyl‐5,5‐diphenyl‐3,5‐dihydro‐4H‐1,2,3‐triazol‐4‐on
Authors: Quast Helmut , Hergenröther Thomas 
Published: July 2007

AbstractPhotolysis of 3‐Methyl‐5,5‐diphenyl‐3,5‐dihydro‐4H‐1,2,3‐triazol‐4‐one[1]Irradiation (λ, ≥ 280 nm) of a degassed solution in deuterated benzene of the dihydro‐1,2,3‐triazolone 5 yields the dihydroindolone 7, the imine 9, and its photoreduction product 10, besides molecular nitrogen.
Darstellung und Eigenschaften von und Reaktionen mit metallhaltigen Heterocyclen, LXXIX. Synthese eines Diphosphamanganacyclopentens durch Alkin–Insertion in die Mn–P–Bindung eines Diphosphamanganacyclopropans
Authors: Lindner Ekkehard , Darmuth Monika , Fawzi Riad , Steimann Manfred 
Published: July 2007

Metal–Containing Heterocycles: Preparation, Properties and Reactions, LXXIX[1a]. – Synthesis of a Diphosphamangana–cyclopentene by Alkyne Insertion into the Mn–P Bond of a DiphosphamanganacyclopropaneInsertion of the alkyne ZCCZ with ZCO2Me into the Mn–P bond of the diphosphamanganacyclopropane results in the formation of the thermally and kinetically stable diphosphamanganacyclopentene (2). According to an X–ray structural analysis 2 crystallizes in the orthorhombic space group P212121 with Z  4.
Retro [1,4]‐Brook Rearrangements of Nonconjugated Secondary α‐Lithio Ethers: Proof of Stereospecificity and of Retention of Configuration at the Carbanion Center
Authors: Hoffmann Rolf , Brückner Reinhard 
Published: July 2007

AbstractThe syntheses of two pairs of diastereomeric γ‐(trialkylsilyloxy) α‐(tributylstannyl) ethers (syn‐ and anti‐6b, syn‐ and anti‐9) are described. Treatment of each of these compounds with nBuLi in THF at −78°C furnished α‐lithiated ethers which underwent retro [1,4]‐Brook rearrangements at that temperature within 15–30 min. After aqueous workup, the α‐silyl ethers syn‐14, anti‐14, syn‐11, and anti‐11, respectively, were isolated isomerically pure in 78–93% yield. Comparison of the stereochemistry of starting materials and products shows that these rearrangements proceed stereospecifically and with retention of configuration at the carbanion center. In a cross–over experiment under similar conditions, a 1:1 mixture of the (tributylstannyl) ethers syn‐9 and syn‐6b gave, via the intermediacy of a 1:1 mixture of the α‐lithiated ethers syn‐13 and syn‐10, the α‐silyl ethers syn‐11 and syn‐14 exclusively. They represent the outcome of intramolecular rearrangements rather than intermolecular processes.