bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lithiated 5,6‐Dihydro‐4H‐1,2‐oxazines: Synthesis, Highly Diastereoselective Reactions with Electrophiles, and Subsequent Transformations
Authors: Reißig Hans‐Ulrich , Hippeli Claudia 
Published: July 2007

AbstractThe 6‐(trimethylsilyl)methyl‐substituted 1,2‐oxazine 1 can smoothly be deprotonated with n‐butyllithium at C‐4 to give a lithiated species which reacts with a variety of electrophiles to provide the new 1,2‐oxazines 5 – 16 in good yields. Besides the preparative aspect of these transformations, the high stereoselectivity of many reactions is also interesting from a mechanistic point of view. By deprotonation of the 4‐deuterated compound 5a it has been proven that n‐butyllithium removes exclusively the proton (or deuteron) cis to the 6‐CH2SiMe3 group. Also, in most cases the reaction of lithiated 1 with electrophiles occurs with overall retention of configuration to afford preferentially cis‐1,2‐oxazines (series a). A mechanistic proposal for this highly stereoselective deprotonation process, which seems to be governed by the 1,2‐oxazine oxygen, is discussed including a comparison with a recently reported ab initio calculation dealing with oxime ethers. Similar deprotonation/substitution reactions are described for 1,2‐oxazines 14, 2, 3, and 4. Possibly due to a differing carbanion structure a deviating behavior is observed in some cases. Several acidinduced and reductive ring‐opening reactions of 1, 6a, 8a, and 14a demonstrate the potential of 4‐substituted 1,2‐oxazines for the stereoselective synthesis of polyfunctionalized compounds.
Stereospezifische Umwandlungen des (+)‐2‐ und (+)‐3‐Carens in optisch aktive Siebenring‐Systeme
Authors: Eilbracht Peter , Winkels Irmgard 
Published: July 2007

Stereospecific Conversions of (+)‐2‐ and (+)‐3‐Carene into Optically Active Seven‐Membered Ring SystemsThe reactions of (+)‐2‐carene (6b) and (+)‐3‐carene (15) with iron carbonyls are studied under various conditions. Besides double bond isomerization and interconversion of the two isomeric hydrocarbons, at least two different modes of ring opening leading to six‐ and seven‐membered ring products are observed. Under mild conditions the primary ring opening complex 7b is isolated without loss of sterical information. Carbonylation of 7b under various conditions yields optically active cycloheptane systems 18, 19, and 20 or the bicyclic systems 9b and 10b.
Neue O6‐Makrocyclen mit 2,2‐Bis(2‐furyl)propan‐Einheiten
Authors: Gast Achim , Breitmaier Eberhard 
Published: July 2007

New O6 Macrocycles with 2,2‐Bis(2‐furyl)propane UnitsThe macrocycles 3a and 6 are prepared in 29 and 16% yield by cyclization of dilithiated 2,2‐bis(2‐furyl)propane (1) and 2,5‐bis[1‐(2‐furyl) 1‐methylethyl]furan (5), respectively, with ethyl N,N‐dimethylcarbamate (2).
Die Kristallstrukturen von Kalium‐, Rubidium‐ und Cäsium‐trifluororthocarbonat mit einer Bemerkung zum Bariumsulfat‐Typ1
Authors: Arlt Joachim , Jansen Martin 
Published: July 2007

The Crystal Structures of Potassium, Rubidium, and Cesium Trifluororthocarbonate and a Remark Concerning the Barium Sulfate Type1)Crystals of potassium, rubidium, and cesium trifluororthocarbonate (9a, 9b, and 9c) have been grown by Ostwald ripening in CH3CN applying a COF2 pressure of 3 bar. According to X‐ray single‐crystal structure analysis, 9a, 9b, and 9c belong to the baryte‐structure family with an pseudotetrahedral anion being dynamically disordered at room temperature. All of the title compounds undergo a phase transition into a monoclinic, completely ordered low‐temperature form, which has been refined for 9c. The C – O bond seems to be shortened by polar interactions. The results obtained with 9a, 9b, and 9c at room temperature indicate that the type of disorder found in 9 might be generally present in baryte‐type compounds.
Addition von Phosphor‐Nucleophilen an Benzothiet
Authors: Eckes Heinz‐Ludwig , Niedermann Hans‐Peter , Meier Herbert 
Published: July 2007

Addition Reactions of Phosphorus Nucleophiles to BenzothieteTrialkyl phosphites 4 add to the o‐quinoid form 2 of benzothiete (1) to yield the phosphonates 6. An intermolecular migration of an alkyl group from oxygen to sulfur is the most important feature of this transformation. The rearrangement – related to the Arbuzov reaction – can be avoided in a two‐step process by the subsequent action of PCl3 and alcohol; thus the phosphonates 10 are generated. Analogous to 2 → 6, dimethyl phenylphosphinate (11) furnishes 13. In contrast, the cyclic esters 14a–d form 2:1 adducts, namely the 12‐ to 15‐membered heterocyclic compounds 17a – d. An intramolecular rearrangement in a 1:1 adduct is only observed for the 1,3,2‐dioxaphosphepine 14e, a benzylic system which allows an SN1 process generating the 1,6,2‐oxathiaphosphecine 18e. A similar rearrangement at a tertiary carbon center is prevented by the competitive addition of water (1 + 14f → 20).
Notizen/Notes Synthesis of 1‐Phenyl‐1,2‐ and 4‐Phenyl‐1,5‐dihydropentalenes
Authors: Griesbeck Axel G. 
Published: July 2007

AbstractAn efficient one‐pot synthesis of 3‐substituted 1‐phenyl‐1,2‐dihydropentalenes from α,β‐unsaturated ketones is described. These compounds can be rearranged to their 1,5‐dihydro isomers using different methods such as acid catalysis and vacuum‐flash thermolysis or by chromatography on alumina.
[(BH2)6S4]2−, [(BH2)6Se4]2−: neue Chalcogenoborwasserstoff‐Anionen mit Adamantanstruktur
Authors: Binder Herbert , Loos Helge , Dermentzis Konstantinos , Borrmann Horst , Simon Arndt 
Published: July 2007

[(BH6)2]S4]2−, [(BH2)Se4]2−: New Chalcogenoboron Hydride Anions with Adamantane StructureThe reaction of THF·BH3/NaBH4 (2: 1) with H2S produces Na[H3B‐μ2‐S(B2H5)] (5) with hydrogen evolution. 5 reacts with an excess of H2S to give Na2[(BH2)6S4] (3a), which is also formed in the reaction of THF·BH3 with NaSH or anhydrous Na2S. These reactions proceed via 5 and the intermediates 7 or 8 by loss of BH–4 and cyclization. The analogous compound Na2[(BH2)6Se4] (4a) is obtained by the reaction of elemental selenium with NaBH4 (1:1) in triglyme. The primary product is Na2[H3B–Se–Se–BH3] (9). Treatment of 9 at 100 – 110°C yields 4a and polymers, 3a and 4a react with CsBr to form the crystalline compounds Cs2[(BH2)6Se4]·CsBr (3b) and Cs2–[(BH2)6Se4]·CsBr (4b), characterized by X‐ray structure determinations. The anions of 3b and 4b consist of an adamantane skeleton. The Br− ion is octahedrally coordinated by Cs+ ions. The Cs6Br octahedra share faces to form columns along the hexagonal c axis. The crystal structures of the isotypic compounds 3b and 4b are closely related to the structure of CsNiCl3.
Stereoselective Synthesis of Alcohols, XXXVII. Origins of Stereoselectivity in Reactions of α‐Substituted Allylboronates with Aldehydes
Authors: Hoffmann Reinhard W. , Jens Wolff J. 
Published: July 2007

AbstractRate constants for the addition of α‐substituted allylboronates 4 (XH, Cl, Br, OCH3, SCH3] to aldehydes have been measured. The results have been used to differentiate between different models that have been advanced to account for the high proportion of (Z)‐configurated homoallyl alcohols 5 formed in allylboration reactions. Attempts have been made in this context to detect ate‐complex formation between benzylboronates and aldehydes.
β‐Aminoketone als Schlüsselverbindungen zur Synthese von Pyridinen: Ein neuartiger, leistungsfähiger Zugang zu kondensierten Bi‐ und Terpyridinen
Authors: Westerwelle Ulrich , Esser Achim , Risch Nikolaus 
Published: July 2007

β‐Amino Ketones as Key Intermediates in the Synthesis of Pyridines: A Novel and Efficient Route to Annelated Bi‐ and TerpyridinesThe hydrochlorides of β‐amino ketones 1a – e (Mannich bases) are easily obtained starting compounds for a novel synthesis of pyridines. Condensation with the heteroaromatic ketones 8, 9, and 10 yields 5,6‐dihydro‐1,10‐phenanthrolines 3a – d, 13 and 4,5‐diazafluorenes 4a – d, which have not yet been described in literature. Symmetrical terpyridines 3e, 4e are formed in a one‐step reaction of 8, 9 with dimethylmethylenammonium chloride in the presence of an ammonia source.
Reactions of Organic Anions, 177. Vicarious Nucleophilic Substitution of Hydrogen, Bisannulation and Competitive Reactions of α‐Haloalkyl Carbanions with Bicyclic Azaaromatic Compounds
Authors: Makosza Mieczyslaw , Golinski Jerzy , Ostrowski Stanislaw , Sahasrabudhe Arvind B. , Rykowski Andrzej 
Published: July 2007

AbstractCarbanions of α‐haloalkyl aryl sulfones, sulfonates, and sulfonamides react with bicyclic heteroaromatic compounds (quinoxalines, naphthyridines, and 5‐azaquinoxalines) according to two general pathways: vicarious nucleophilic substitution of hydrogen and/or bisannulation. In some cases other competitive reactions such as SNAr are observed. Factors governing the direction of these reactions are discussed in terms of the charge distribution in the anionic σ adducts and the reaction conditions.
Struktur und Reaktivität von isoanellierten heterocyclischen Systemen mit 4n;‐π‐ und (4n + 2)‐π‐Elektronen, XVIII. Benzo[c]thiophene mit symmetrischer Struktur: Modifizierte und optimierte Herstellung nach der S‐Oxid‐Route
Authors: Kreher Richard P. , Kalischko Jürgen 
Published: July 2007

Structure and Reactivity of Isoannullated Heterocyclic Systems with 4n;‐π and (4n + 2)‐π Electrons, XVIII. – Benzo[c]thiophenes with Symmetric Structure: Modified and Optimized Preparation by the S‐Oxide RouteBenzo[c]thiophenes (15) with symmetric structure have been prepared efficiently from 1,3‐dihydrobenzo[c]thiophene 2‐oxides (9) by reaction with aluminium oxide, by O‐acylation with trifluoroacetic anhydride, or O‐alkylation with methyl trifluoromethanesulfonate. The aromatization of the S‐oxides 9 is achieved by O‐functionalization, subsequent elimination, and consecutive deprotonation.
Zur Reaktivität des Silaethens Me2SiC(SiMe3)2: Stereospezifität der Diels‐Alder‐Reaktionen mit Hexadienen1,2
Authors: Wiberg Nils , Fischer Gerd , Wagner Susanne 
Published: July 2007

On the Reactivity of Silaethene Me2SiC(SiMe3)2: Stereospecificity of Diels‐Alder Reactions with Hexadienes1,2)[4 + 2] Cycloaddition of trans,trans;‐ and cis,trans;‐2,4‐hexadiene to silaethene Me2SiC(SiMe3)2 (1) takes place stereo‐specifically in one step with formation of 3 and 4, respectively. In addition, both reactions lead to ene products 5, 6.
Großflächige, starre Makrocyclen aus 1,4‐Diphenylbutadiin‐Bauteilen
Authors: Kadei Klaus , Vögtle Fritz 
Published: July 2007

Flat and Rigid Macrocycles Based on 1,4‐Diphenylbutadiyne Units[1.1](3,3′)‐1,4‐Diphenylbutadiynophanes of type Ia,b (e.g. 1 – 4) are obtained by coupling the diethynyl derivatives 18 – 21 by means of CuCl/CuCl2. The properties of 1 – 4 (UV, NMR, charge transfer) are compared to 1,4‐diphenylbutadiyne. In contrast to 1,4‐diphenylbutadiyne, 1 and 2 (type Ia) are highmelting, colorless solids, which are sparingly soluble in common organic solvents. The better soluble compounds 3 and 4 (type Ib) are also prepared. The macrocycles 1 – 4 consist of two “isolated” 1,4‐diphenylbutadiyne units. In contrast to 1,4‐diphenylbutadiyne they do not seem to form charge‐transfer complexes with tetracyanoethene (TCNE) in CH2Cl2.
Mehrfachbindungen zwischen Hauptgruppenelementen und übergangsmetallen, XC. Selektive Bildung von Alkylrheniumoxiden aus Glykolat‐Komplexen
Authors: Herrmann Wolfgang A. , Watzlowik Petra , Kiprof Paul 
Published: July 2007

Multiple Bonds between Main Group Elements and Transition Metals, XC. – Selective Formation of Alkylrhenium Oxides from Glycolato ComplexesAlkylrhenium(VII) and alkylrhenium(VI) oxides, previously not known or hardly accessible, are selectively synthesized from glycolato(O,O') complexes. These are formed in easy terms from methyltrioxorhenium(VII) and aliphatic vic‐diols, e.g. glycol and pinacol, by both redoxneutral and reductive condensation reactions (ReVII → ReVI), respectively. The dinuclear glycolato complex 3 exhibits a centrosymmetric molecular structure with an octahedral core geometry around the metal atom. The mononuclear Re(VII) compound 2 forms a distorted trigonal bipyramidal structure (single crystal X‐ray diffraction).
Dicarbonylgold(I)‐hexafluorouranat(VI), Au(CO)2UF6
Authors: Adelhelm Manfred , Bacher Walter , Höhn Ernst Gerhard , Jacob Eberhard 
Published: July 2007

Dicarbonylgold(I) Hexafluorouranate(VI), Au(CO)2UF6Elemental gold reacts with UF6 in the presence of CO in anhydrous HF to form quantitatively a complex compound, whose IR spectra and analysis are consistent with the formula [Au(CO)2][UF6].
Alkylations of (R,R)‐2‐t‐Butyl‐6‐methyl‐1,3‐dioxan‐4‐ones which are not Possible with Lithium Amides may be Achieved with a Schwesinger P4 Base
Authors: Pietzonka Thomas , Seebach Dieter 
Published: July 2007

AbstractEnolates A of the dioxanones specified in the title, when generated with lithium amide bases, can only be alkylated with highly reactive electrophiles, and only once. With Schwesinger's t‐Bu‐P 4 base (a very strong, so‐called neutral base, containing 4P and 13N atoms capable of bearing a positive charge in the conjugate P4H+ cation) the dioxanone 1 can be doubly alkylated even with iodobutane (products 16, 17). The 5,6‐dimethyl‐ and 5‐benzyl‐6‐methyldioxanone 2 and 3 can be alkylated diastereoselectively with the formation of quaternary centers at C(5) (products 4, 8—14). In one case, the configuration of the product 4 obtained was determined by conversion to a β‐lactone 6 and an olefin 7 (a previous assignment had to be revised). Even the 2,5,6,6‐tetraalkyl‐substituted dioxanone 19 could be further alkylated (→ 20 + 21). Five of the new alkylation products were hydrolyzed to the parent 3‐hydroxy‐carboxylic acids 5, 22 — 25. The enormous reactivities achieved with the inherently labile enolates and the P411+ counterions are discussed.
Große Übergangsmetallcluster, VIII. Wie verhalten sich trägergestützte Rh55‐Cluster im Hydroformylierungsprozeß?
Authors: Schmid Günter , Küpper Rolf , Hess Holger , Malm Jan‐Olle , Bovin Jan‐Olov 
Published: July 2007

Large Transition Metal Clusters, VIII. ‐ How Do Supported Rh55Clusters Behave in the Hydroformylation Process?Two‐shell rhodium clusters of the type Rh55L12Clx[L = P(tBu)3, x = 20; L = PPh3, x = 6] can be anchored on TiO2and Na‐ Y‐zeolite. High resolution transmission electron microscopy (HRTEM), BET, and DSC investigations prove that the clusters, about 20 Å in diameter, are fixed on the entrances of the micropores of the supports. The supported clusters catalyze the hydroformylation of ethene and propene variously. During the hydroformylation of ethene without a solvent or in aqueous suspension the catalyst is inactive after a few cycles. However, there is no loss of activity even after 27 experiments if propene is hydroformylated in an aqueous medium.
Zweifache Borylierung von Benzolderivaten mit (Diisoalkylamino)boradiyl‐Einheiten
Authors: Meller Anton , Böker Christian , Seebold Uwe , Bromm Dietmar , Maringgele Walter , Heine Andreas , Herbst‐Irmer Regine , Pohl Ehmke , Stalke Dietmar , Noltemeyer Mathias , Sheldrick George M. 
Published: July 2007

Twofold Borylation of Benzene Derivatives with (Diisoalkylamino)boradiyl UnitsThe reaction of subvalent boron species generated by the defluorination of difluoro(diorganylamino)borane with Na/K alloy in the presence of 1,4‐disubstituted benzene derivatives leads to products which contain two (diorganylamino)boradiyl units and two remaining double bonds which are located on the substituted C atoms. Compounds 5 to 8 exhibit structures based on a 2,8‐diborabicyclo[3,2,1]octa‐3,6‐diene skeleton while 9 shows a skeleton with a 1,3a,4,6a‐tetrahydroborolo[3,2‐b]borole structure. The latter structure corresponds to that of 1 obtained in the same reaction with benzene. The compounds are characterized by elemental analyses and spectroscopically [MS, NMR (1H, 11B, 13C, 15N, 19F, 29Si)]. X‐ray structure analyses are presented for 1, 6, 7, 8, and 9.
Vom Lithium‐Derivat des Aminodi‐tert‐butylfluorsilans zu Cyclodi‐, ‐tri‐ und ‐tetrasilazanen
Authors: Kottke Thomas , Klingebiel Uwe , Noltemeyer Mathias , Pieper Ursula , Walter Simone , Stalke Dietmar 
Published: July 2007

Aminodi‐tert‐butylfluorosilane (CMe3)2 SiFNH2 reacts with BuLi in hexane to give the lithium derivative 1, which crystallizes from TMEDA with formation of the dimer 2 [(CMe3)2SiFNHLi(TMEDA)]2. LiF elimination from 1 or 2 leads to cyclodi‐ (3), ‐tri‐ (4), and ‐tetrasilazane (6). 3 is the main product of the LiF elimination from 2 and 4 the main product resulting from 1. Cyclotetrasilazane 6 is the most planar eightmembered Si‐N ring known so far. Chain compound 5 is the direct precursor of 4. The crystal structures of 2, 5, and 6 are described.From the Lithium Derivative of Amino‐di‐tert‐butylfluorosilane to Cyclodi‐, ‐tri‐, and ‐tetrasilazanes
Beiträge zur Chemie des Bors, 209. 1,2‐Diboran(4)diyl‐ und 1,3‐Triboran(5)diyl‐ditosylate und ‐bis(triflate): Elektronenpräzise Polyboran‐Derivate mit aktiven Austrittsgruppen
Authors: Nöth Heinrich , Wagner Matthias 
Published: July 2007

Contributions to the Chemistry of Boron, 209. — 1,2‐Diborane(4)diyl and 1,3‐Triborane(5)diyl Ditosylate and Bis(triflate): Electron‐Precise Polyborane Derivatives with Active Leaving GroupsIntroduction of the tosylate or triflate group into dimethylamino polyboranes gives electron‐precise polyborane derivatives of high reactivity. Five representatives 1 – 4 of these types of compounds are reported. The RSO3 groups strengthen the B – N bond while they are good leaving groups as shown by alkylation reactions when using LiR compounds. The X‐ray structure of B2(NMe2)2(tos)2 (1) reveals C2 symmetry, and this also holds for B2(NMe2)2(CCPh)2 (7). While the two BNO planes in 1 include an angle of 80.8°, the two BNC planes in 7 are closer to orthogonality (84.6°). In contrast, the bis(9‐fluorenyl)diborane 10 reveals different structures in solution and the solid state. Experimental results correspond fairly well with MNDO calculations on model compounds B2(NH2)2X2, particularly with B – B and B – N bond lengths and conformations. They also suggest that nucleophilic substitutions at 1 – 4 may proceed by a dissoziative process.
Zur Reaktivität des Silaethens Me2Si = C(SiMe3)2: Relative Geschwindigkeiten der Diels‐Alder‐Reaktionen mit organischen Dienen1,2)
Authors: Wiberg Nils , Wagner Susanne , Fischer Gerd 
Published: July 2007

On the Reactivity of the Silaethene Me2Si = C(SiMe3)2: Relative Rates of Diels‐Alder Reactions with Organic Dienes1,2)[4 + 2] Cycloaddition of dienes to silaethene Me2Si = C(SiMe3)2 is accelerated in the directions: (i) butadiene < isoprene < CH2 = CR – CH = CH2 with R = CH2SiMe2CH‐ (SiMe3)2 (increase in electron donation of the diene substiuents), (ii) trans‐piperylene < 2,3‐dimethylbutadiene (DMB) < isoprene (decrease in steric hindrance of diene substituents), (iii) cis‐piperylene or cis,trans‐hexadiene < trans‐piperylene and trans,trans‐hexadiene (decrease in equilibrium concentration of the cisoid conformer).
Mehrstufige reversible Redoxsysteme, LVI. Kristallstruktur und Leitfähigkeiten der CT‐Komplexe TTF/2‐X‐5‐Me‐DCNQI (X = Cl, Br, I) aus Tetrathiafulvalen und 2‐Halogen‐N,N′‐dicyan‐5‐methyl‐1,4‐benzochinondiimin
Authors: Erk Peter , Hünig Siegfried , Klebe Gerhard , Krebs Martin , Schütz Jost Ulrich Von 
Published: July 2007

Multi‐Step Redox Systems, LVI. – Crystal Structures and Conductivities of the CT Complexes TTF/2‐X‐5‐Me‐DCNQI (X = Cl, Br, I) from Tetrathiafulvalene and 2‐Halogeno‐N,N′‐dicyano‐5‐methyl‐1,4‐benzoquinone DiimineIn contrast to microcrystalline powders single crystals of the title complexes show low conductivities (&10; < sigma‐5 Scm‐1). These properties are based on a peculiar mixed stack arrangement of donor and acceptor molecules within the crystal lattice (space group P21/n).
1,3‐Cyclopentandiyle – Intermediate oder Übergangszustände?
Authors: Roth Wolfgang R. , Bauer F. , Breuckmann Rolf 
Published: July 2007

1,3‐Cyclopentanediyls – Intermediates or Transition States?The energy well of the singlet diradicals 4a and 6 has been determined by the oxygen trapping technique to be 2.7 and 1.9 kcal/mol, respectively. From the oxygen and temperature dependence of the trapping rate of the diradical 4a activation barriers of 2.2 and 4.9 kcal/mol have been derived for the mutual interconversion of the spin isomers with the triplet being the ground state.
Polyarylenes and Poly(arylenevinylene)s, V. Synthesis of Tetraalkyl‐Substituted Oligo(1,4‐naphthylene)s and Cyclization to Soluble Oligo(peri‐naphthylene)s2)
Authors: Koch Karl‐Heinz , Müllen Klaus 
Published: July 2007

AbstractA homologous series of oligo(1,4‐naphthylene)s from the binaphthyl 6 to the sexinaphthylene derivative 10 were synthesized successively. The Pd(O)‐catalyzed reaction between aryl bromides and arylboronic acids was used as a coupling method. By appropriate choice of the stoichiometry, the method allowed isolation of the intermediates 20 and 21. Under the influence of potassium in 1,2‐dimethoxyethane the 1,4‐bridged naphthylenes 6—10 were partially cyclized to perylene and terrylene units. This anionic cyclization displayed a high regioselectivity. Complete cyclization to the oligorylenes 3b, 4b and 5b was achieved under the influence of AlCl3 and CuCl2 on the bichromophoric systems 24, 25 and 28. The synthetic sequence allowed substitution by tert‐butyl groups, so that the oligorylenes 2b, 3b, 4b and 5b were amenable to spectroscopic investigations. The trends in absorption maxima and fluorescence are discussed.
Stereoselective Synthesis of Alcohols, XXXVIII Stereoselective Total Synthesis of the Denticulatins
Authors: Andersen Marc W. , Hildebrandt Bernhard , Dahmann Georg , Hoffmann Reinhard W. 
Published: July 2007

AbstractThe total synthesis of the denticulatins 1 is described. Key feature is the efficient generation of the C‐1‐to‐C‐9 building block 37 by three consecutive stereoselective carbon ‐ carbon bond‐forming steps using chiral allylboronates. The C‐10‐to‐C‐17 building block was obtained by kinetic Sharpless resolution of an allylic alcohol followed by an Ireland‐Claisen rearrangement.
Darstellung und Eigenschaften von und Reaktionen mit metallhaltigen Heterocyclen, LXXVII Synthese, Struktur und Reaktivität von Phosphametallacyclopropanen mit isolobalen ER‐ (E = N, P, As, Sb) und Fe(CO)4‐Bausteinen
Authors: Lindner Ekkehard , Heckmann Maria , Fawzi Riad , Hiller Wolfgang 
Published: July 2007

Metal‐Containing Heterocycles: Preparation, Properties, Reactions, LXXVII. – Synthesis, Structure and Reactivity of Phosphametallacyclopropanes with Isolobal ER (E = N,P,As,Sb) and Fe(CO)4 Building BlocksThe phosphidometallates \documentclass{article}\usepackage{amsmath}\pagestyle{empty}\begin{document}$ Li_2 \left\{ {\left[ M \right]\dddot - PPh_2 } \right\} $\end{document} {[M] = (η5‐C5H5)M‐(CO)2}, resulting from the metal hydride complexes H[M]PPh2H [M = Cr (1), Mo (2), W (3)] by reduction with nBuLi, react with the geminal dihalides RECl2 to give the three‐membered phosphametallacyclopropanes [ER = NC6F5 (M = Cr (1a), Mo (2a), W (3a)), PPh (M = Cr (1b), Mo (2b), W (3b)), PC6H11 (M = Cr (1c), Mo (2c), W (3c)), P‐tBu (M = Cr (1d), Mo (2d), W (3d)), P(2,4,6‐(tBu)3C6H2) (M = Cr (1e), Mo (2e), W (3e)), As(2,4,6‐(tBu)3C6H2) (M = Cr (1f), Mo (2f), W (3f)), Sb‐tBu (M = Cr (1g), Mo (2g))]. Reaction of Br2Fe(CO)4 with the corresponding dilithium compounds \documentclass{article}\usepackage{amsmath}\pagestyle{empty}\begin{document}$ Li_2 \left\{ {\left[ M \right]\dddot - PPh_2 } \right\} $\end{document} affords the phosphido‐bridged heterodimetallic complexes . According to X‐ray structural analyses in 2a and 2f the P – E bond distances are shortened while the Mo – E bonds are significantly elongated compared to a single bond. (OC)5CrTHF is added to the Lewis basic E atom in 2b, 2d, and 2g with loss of THF to give P‐tBu (4d), Sb‐tBu (4g)]. By this reaction the antimony‐containing ring 2g is kinetically stabilized. Because of the low basicity of the N atom in 2a no addition was observed. The ring skeleton of 4b and 4g, undergoes no change by Cr(CO)5 coordination as shown by X‐ray structural analyses.