bluuebunny/crossref_metadata_2025_split huggingface dataset:
(E,R,R)‐5‐Alkyliden‐2‐tert‐butyl‐6‐methyl‐1,3‐dioxan‐4‐one: Herstellung aus (R)‐3‐Hydroxybuttersäure, Cuprat‐Additionen und Hydrolysen zu 3‐Hydroxycarbonsäuren mit chiralen sekundären Alkylgruppen in 2‐Stellung
Authors: Amberg Willi , Seebach Dieter 
Published: July 2007

(E,R,R)‐5‐Alkylidene‐2‐tert‐butyl‐6‐methyl‐1,3‐dioxan‐4‐ones: Preparation from (R)‐3‐Hydroxybutyric Acid, Cuprate Additions, and Hydrolyses to 3‐Hydroxycarboxylic Acids with Chiral Secondary Alkyl Substituents in the 2‐PositionLi enolates of (R,R)‐2‐tert‐Butyl‐6‐methyl‐1,3‐dioxan‐4‐one add to aliphatic or aromatic aldehydes with relative topicity Re,Re (2: 1 to 10: 1, 9 examples). The title compounds are obtained from these aldol adducts by dehydration through mesylates (5 examples, total yields from the dioxanone 35–55%). Cuprate additions (R2CuLi/F3BOEt2) to these alkylidene dioxanones and quenching with acid produce 5,6‐trans‐substituted dioxanones in an overall anti addition of R and H to the exocyclic double bond from the Re and the Si face, respectively (5: 1 to 40:1, 13 examples, 50–80%). The configurations of the products were assigned by NMR spectroscopy and by chemical correlation. In 8 cases, the dioxanone products were hydrolysed to the corresponding free β‐hydroxycarboxylic acids. It is also demonstrated that transacetalisation of the aldol adducts leads to 1,3‐dioxane‐5‐carboxylic acids (acetal‐protected derivatives of “double aldols”, formally derived from acetic acid, 4 examples). Reduction of these acids with LAH, in turn, produces tris(hydroxyalkyl)methanes (acetal‐protected, 3 examples). All chiral products described herein are enantiomerically pure.
Synthese und Struktur von Bis[bis(diisopropylamino)phosphino]chalkogeniden
Authors: Westerman Hermann , Nieger Martin , Niecke Edgar 
Published: July 2007

Synthesis and Structure of Bis[bis(diisopropylamino)phosphino]chalcogenidesPhosphorodiamidous chalcogeno‐anhydrides [(R2N)2P]2X (R = Me2CH; X = S, Se, Te) (2a‐c) have been obtained by insertion of elemental sulfur, selenium, or tellurium into the P–P bond of the corresponding diphosphane (1). The structure of 2a and 2c has been confirmed by an X‐ray diffraction.
Derivate des Borols, XVI Bis(borol)nickel‐Komplexe2)
Authors: Herberich Gerhard E. , Englert Ulli , Hostalek Martin , Laven Ralf 
Published: July 2007

Derivatives of Borole, XVI1),—Bis(borole)nickel Complexes2)The dilithium 1‐(dialkylamino)dihydroborolediides Li2[C4H4‐BNR2] 2a, b: R = Me, Et) react with NiCl2 · DME to give bis(borole)nickel complexes Ni(C4H4BNR2)2. Nucleophilic substitution reactions are used to produce a large variety of derivatives Ni(C4H4BR)2 1 (e.g. R = H, tBu, F, Cl, Br, I, OH, OMe). Treatment of Ni(C4H4BCl)2 (tg) with LiO(CH2)3OLi in THF produces a polymer and a dinuclear complex (μ‐{η5:η5‐[(CH2)3(OBC4H4)2]}2Ni2 (3) which crystallizes from CH2Cl2 as solvate 3 · CH2Cl2. The complexes 1g and 3 · CH2Cl2 are characterized by X‐ray diffraction work. Barriers to internal ring‐ring rotation are measured by variable‐temperature NMR spectroscopy. The B—H bond of Ni(C4H4BH)2 (1a) is remarkably inert and does not react with H2O or with carboxylic acids in THF at room temperature. With PhCHO slow formation of the benzyloxy compound Ni(C4H4BOCH2Ph)2 (1 m) is observed at 100°C. For typical complexes such as the phenyl derivative 1e cyclic voltammetry in CH2Cl2 reveals an irreversible oxidation at 1.32 and a quasi‐reversible reduction at –1.37 V vs. SCE.
Darstellung von (Perfluoralkyl)halogeno‐1,3‐diselenetanen aus entsprechenden Selenocarbonylfluoriden und Umsetzungen mit Bortrichlorid sowie Arsenpentafluorid1)
Authors: Haas Alois , Spehr Michael , Boese Roland 
Published: July 2007

Preparation of (Perfluoroalkyl)halogeno‐1,3‐diselenetanes from the Corresponding Selenocarbonyl Fluorides and Reactions with Boron Trichloride or Arsenic Pentafluoride1)Reactions of Hg(SeRt)2 (Rt = C2F5, C3F7, CF3) with (C2H5)2 All or All3 in octamethylcyclotetrasiloxane produce the unstable perfluoroalkaneselenocarbonyl fluorides 1 [R1 = CF3 (1 a), C2F5 (1 b), CF3Se (1 c)]. These compounds are very reactive and polymerize to rubberlike products. On heating the polymers decompose almost quantitatively to the monomers or dimers. In CFCl3 solution 1 dimerizes at 20°C in sunlight to the corresponding cis/trans‐1,3‐diselenetanes 2. The structure of 2 b is determined by single crystal X‐ray diffraction. Different selenocarbonyl derivatives add to unsymmetrically substituted 1,3‐diselenetanes 3. 1 a and 1 b react with cyclopentadiene to form the [4 + 2] cycloaddition products 4a and 4c. Halogen exchange reactions take place between 2a — d and BCl3. The cis‐isomers react much faster than the trans‐isomers to give a mixture of cis‐, trans‐forms of 5. When 2c,d is treated with BCl3 it is possible to isolate and characterize the pure trans‐isomer 2d, which is separated by preparative gas chromatography from 5c,d. Fluorine abstraction with formation of 1,3‐diselenetan‐2‐ylium ions (6a — f) are accomplished by reactions of 2 or 3 with AsF5 in SO2.
Zur Kenntnis des “Silanphosphimins” (Phosphasilaethens) tBu2SiPSitBu31,2)
Authors: Wiberg Nils , Schuster Harad 
Published: July 2007

On the Knowledge of the “Silanephosphimine” (Phosphasilaethene) tBu2Si = PSitBu31,2)The lithium phosphide 3 acts as a source for the “silanephosphimine” 2. Thermolysis of 3 at 80–120°C in the presence of Li⊕ (tBu3Si⊖PH), CH2 = CMe2, or CH2 = CHCH = CH2 leads to products 4, 7 or 8, whose formation is interpretable by the reaction of the reactants with intermediately formed 2.
Übergangsmetall‐substituierte Diphosphene, XX1) Synthese und Eigenschaften des Tetrahedrans [(η5‐C5Me5)(CO)2FeP–PtBu]Fe2(CO)6 und der metallierten 1,3‐Diphospha‐2‐propanone [(η5‐C5Me5)(CO)2Fe–PC(O)–PR]Fe2(CO)6 [R = tBu, 2,4,6‐(CF3)3C6H2]
Authors: Weber Lothar , Schumann Hans 
Published: July 2007

Transition‐Metal‐Substituted Diphosphenes, XX1). – Synthesis and Properties of the Tetrahedrane [(η5‐C5Me5)(CO)2‐FeP–PtBu]Fe2(CO)6 and the Metalated 1,3‐Diphospha‐2‐propanones [(η5‐C5Me5)(CO)2Fe–PC(O)–PR]Fe2(CO)6 [R = tBu, 2,4,6‐(CF3)3C6H2]The reaction of [η5‐C5Me5)(CO)2FeP(SiMe3)2 (1) with tBuPCl2 (2a) affords the metalated cyclotetraphosphane [(η5‐C5Me5)‐(CO)2FeP–PtBu]2 (4a) besides the metal‐substituted cyclotriphosphane (η5‐C5Me5(CO)2Fe–P[PtBu]2 (5a) and the diphosphane (η5‐C5Me5)(CO)2FeP(SiMe3)P(Cl)tBu (3a), which are detected in the reaction mixture by 31P‐NMR spectroscopy. Treatment of 4a with excess of Fe2(CO)9 leads to the tetrahedrane [(η5‐C5Me5)(CO)2FeP–PtBu]Fe2(CO)6 (6a) and the 1,3‐diphospha‐2‐propanone derivative [(η5‐C5Me5)(CO)2FePC(O)‐P–tBu]Fe2(CO)6 (7a). Similarily, an analogous complex 7c is obtained from the reaction of in situ prepared (η5‐C5Me5)‐(CO)2FePP–C6H2(CF3)3‐(2,4,6) with an excess of Fe2(CO)9.
On the Electronic Structure of Phosphabutatriene and Related Phosphacumulenes. A Theoretical Study
Authors: Schoeller Wolfgang W. , Welz Udo , Haug Wilfried , Busch Thilo 
Published: July 2007

AbstractThe title compound phosphabutatriene possesses two energetically closely spaced frontier orbitals, as in methylenephosphane and in phosphaallene. They are built up from the π system or the s̀ orbital of phosphorus by interaction with neighboring π bonds. The extension of these frontier orbitals over all (heavy) atoms makes self‐dimerization to different cyclobutane derivatives feasible. Substituent effects on the ordering of s̀ and π are analyzed. Vibrational analyses indicate PC vibrations of low intensity which decrease with increasing length of the heterocumulene chain. The analysis is extended to the two next higher homologs, which are hitherto experimentally unknown.
Untersuchungen zum Reaktionsverhalten von Benzocyclopropen unter Yb(fod)3‐Katalyse
Authors: Neidlein Richard , Krämer Bettina 
Published: July 2007

Experiments Concerning the Reactions of Benzocyclopropene under Yb(fod)3 Catalysis1,3‐Dihydroisobenzofuran derivatives 3a – e and 5a – c are obtained by reactions of α,β‐unsaturated carbonyl compounds with benzocyclopropene (1). The yields increase by addition of Yb(fod)3. Aromatic aldehydes react in the same way. Yb(fod)3 has no influence on the reactions of α,β‐unsaturated hydrazones with 1.
Synthese heterocyclischer Dialkine und deren Umsetzung mit CpCo(CO)2
Authors: Gleiter Rolf , Rittinger Stefan , Langer Heinrich 
Published: July 2007

Synthesis of Heterocyclic Diynes and their Reaction with CpCo(CO)2The preparation of the heterocyclic diynes 1,6‐dithia‐3,8‐cyclodecadiyne (1b), thia‐3,8‐cyclodecadiyne (11), 1‐thia‐6‐selana‐3,8‐cyclodecadiyne (12), oxa‐3,8‐cyclodecadiyne (13), 1,6‐dioxa‐3,8‐cyclodecadiyne (14), 1‐oxa‐6‐thia‐3,8‐cyclodecadiyne (15), 1,6‐diselena‐3,8‐cyclodecadiyne (26), thia‐3,9‐cyclounde‐cadiyne (22a), thia‐3,13‐cyclopentadecadiyne (22b) and its selena analogues 23a, 23b is described. The thia and monoselena compounds are obtained by a thia‐ or selenacyclization of the corresponding dibromides. Compound 26 has been obtained by a Misumi coupling reaction. The thiacycloalkadiynes of medium‐sized rings (10, 11) react with CpCo(CO)2 to yield [2,2](2,5)thiophenophane derivatives. Acyclic thiadialkynes or thiacycloalkadiynes of larger ring size (22b) with CpCo(CO)2 by [2 + 2 + 2] cycloaddition.
Ten‐Membered Heterocyclic Diynes X‐ray Structure Analysis and PE‐Spectroscopic Investigations
Authors: Gleiter Rolf , Rittinger Stefan , Irngartinger Hermann 
Published: July 2007

AbstractX‐ray investigations on the ten‐membered heterocyclodiynes 1 – 4 reveal a chair‐like conformation for all four compounds. The triple bonds are oriented parallel to each other, the distances between them varying between 3.10 Å (2) and 2.91 Å (1). All triple bonds are slightly bent, the deviation from 180° varies between 6 – 10°. The photoelectron spectra of 1 and 3 – 6 have been recorded. The first six bands have been assigned by comparing them with related species and MO calculations. In the case of 3 – 6, the HOMO is predicted to be a long pair combination. The splitting between the in‐plane π‐linear combinations η−i, η+i ranges from 0.9 eV (5) up to 1.5 eV (4).
Reactions of Benzocycloheptenes with Dienophiles
Authors: Adam Waldemar , Balci Metin , Ceylan Zeynep , Hinz Ricardo Francisco 
Published: July 2007

AbstractThe Diels‐Alder reactions of 5H‐benzocycloheptene (1) with tetracyanoethylene (TCNE) afforded the [2+2] and [4+2] cycloadducts 7, 8, and 10 and the benzodicyanoheptafulvalene 9. The norcaradiene product 10 was synthesized independently by cycloaddition of TCNE to 7H‐benzocycloheptene (3). The addition of 4‐methyl‐1,2,4‐triazoline‐3,5‐dione (MTAD) to 3 gave bis‐urazole 13, which was formed by ene reaction followed by [4+2] cycloaddition. The spirocycloheptatriene 15 gave with 4‐phenyl‐1,2,4‐triazoline‐3,5‐dione (PTAD) the bisurazole 16.
Abfangen von Hexafluorselenoaceton durch Cycloadditionen mit Dienen sowie Darstellung von Hg[SeCF(CF3)2]2 und (CH3)3SiSeCF(CF3)2
Authors: Haas Alois , Limberg Christian , Spehr Michael 
Published: July 2007

Scavenging of Hexafluoroselenoacetone by Cycloadditions with Dienes and Preparation of Hg[SeCF(CF3)2]2 and (CH3)3SiSeCF(CF3)2Bis(perfluoroisopropylseleno)mercury (2) was obtained from 2,2,4,4‐tetrakis(trifluoromethyl)‐1,3‐diselenetane (1) and HgF2 in DMF, and (perfluoroisopropylseleno)trimethylsilane (3) from 2 and (CH3)3Sil. The reaction of 2 with (C2H5)2All as well as the pyrolysis of 1 yield a deep purple liquid in very small amounts, not sufficient for further characterisation, which is assumed to be hexafluoroselenoacetone (4). However, 4 is formed as an intermediate in the reaction of hexafluoropropene with CsF and selenium and can be trapped by isoprene or anthracene to form 5a, 5b, and 6, respectively. In boiling benzene a transformation of (CF3)2CSe from 6 to 2,3‐dimethyl‐1,3‐butadiene is accomplished yielding 7 in a retro Diels‐Alder cleavage.
Röntgenstrukturuntersuchung von α‐(Trimethylsilyl)benzyllithium·Tetramethylendiamin [C6H5CH(SiMe3)Li·TMEDA] und α‐(Phenylthio)‐benzyllithium·3 Tetrahydrofuran [C6H5CH(SPh)Li·(THF)3] – zwei zentral‐chirale Benzyllithium‐Verbindungen
Authors: Zarges Wolfgang , Marsch Michael , Harms Klaus , Frenking Gernot , Boche Gernot , Koch Wolfram 
Published: July 2007

Crystal Structure of α‐(Trimethylsilyl)benzyllithium·Tetramethylethylendiamin [C6H5CH(SiMe3)Li·TMEDA] und α‐(Phenylthio)‐benzyllithium·3 Tetrahydrofuran [C6H5CH(SPh)Li – (THF)3] – Two Benzyllithium Compounds with Central ChiralityThe crystal structure analyses of [C6H5CH(SiMe3)Li·TMEDA] (6) and of [C6H5CH(SPh)Li·(THF)3] (7, in which the positions of the benzylic hydrogen atoms have been determined experimentally, reveal compounds with pyramidal benzylic carbon atoms. In 6 lithium is λ2‐bound to Cipso and α of the substituted benzylic anion which leads, together with the TMEDA molecule, to a tetra‐coordinated lithium atom. In 7 only one Li – C bond is formed, namely that to Cα. Additional coordination with three THF molecules results also in a tetracoordinated lithium atom, The extent of the pyramidalization in 6 and 7 is qualitatively in agreement with quantum‐mechanical ab initio calculations [G86, MP2/6‐311+ + G(d,p)].
Inter‐ and Intramolecular Hetero Diels‐Alder Reactions, 31. Synthesis of D‐Homoestrone Derivatives by Tandem Knoevenagel Hetero Diels‐Alder Reactions from Natural Estrone
Authors: Tietze Lutz F. , Wölfling János , Schneider Gyula 
Published: July 2007

AbstractThe tandem Knoevenagel hetero Diels‐Alder reaction of the secoestrone derivative 8 with dimethylbarbituric acid (9a). Meldrum's acid (9b), and the pyrazolones 13a–c stereoselectively affords the D‐homoestrone derivatives 11a, 12, and 14a–c, respectively, with the 16α,17aα configuration in excellent yield. In the reaction of 8 with 9a, b only one diastereomer can be detected, whereas in the reaction of 8 with 13a–c a small amount of the isomeric adducts 15a–c has also been found.
Übergangsmetall‐Stannyl‐Komplexe, 31) Metall, Wasserstoff, Zinn‐Dreizentrenbindung bei Hydrido‐Stannyl‐Komplexen der 6. Nebengruppe
Authors: Piana Hermann , Kirchg äßner Uwe , Schubert Ulrich 
Published: July 2007

Transition‐Metal Stannyl Complexes, 3. – Metal, Hydrogen, Tin Three‐Center Bonding in Group VI Hydrido Stannyl ComplexesThe hydrido stannyl complex (π‐1,3,5‐Me3C6H3)(CO)2Cr(H)‐SnPh3 (1) is prepared by photochemical reaction of (π‐1,3,5‐Me3C6H3)(CO)3Cr with HSnPh3. The 119SnHCr coupling constant (327.6 Hz) and an X‐ray structure analysis [Sn – H 202(4), Cr – H 159(4), Cr – Sn 270.16(6) pm] show that the Sn – H bond is coordinated in an η2 fashion. The complexes (CO)4(R3P)‐W(H)SnPh3 (R3PPh3P, MePh2P) (2) and (CO)3(dppe)M(H)‐SnR3 (MCr, SnR3=SnPh3; MMo, SnR3=SnMe3, SnPh3; MW, SnR3=SnMe3, SnPh2Me, SnPh3) (4 – 6) are obtained either by thermal reaction of (CO)4(R3P)W(THF) or (CO)3(dppe)ML (LTHF, acetone) with HSiR3, or by photochemical reaction of (CO)4(dppe)M with HSnPh3. Reaction of (CO)4(Ph3P)W(THF) with HSnMe3 yields (CO)4(Ph3P)W(Sn‐Me3)2 (3). The Sn,M,H coupling constants in the complexes 2 and (CO)3(dppe)M(H)SnR3 (MCr, Mo) are in the range of 250 – 315 Hz and therefore these complexes seem to contain an η2‐coordinated stannane. Contrary to this, the SnWH coupling constants in (CO)3(dppe)W(H)SnR3 are considerably lower (70 – 90 Hz), suggesting complete oxidative addition of the H – Sn bond. The complexes (CO)3(dppe)M(H)SnPh3 decompose in benzene solution at room temperature to give, inter alia, hexaphenyldistannane. Ph6Sn2 · 2 C6H6 crystallizes in the space group \documentclass{article}\pagestyle{empty}\begin{document}$ R\bar 3 $\end{document} (Z=1); in the crystal lattice the benzene molecules are perpendicular to the three‐fold axis of symmetry of the distannane molecule.
Chromophore Systeme, 2. Konformation und Lichtabsorption von (2‐Alkoxyvinyl)ethandionen
Authors: Effenberger Franz X. , Kramme Roland , Lindner Hans Jörg , Martin Georg , Martin Hans‐Dieter , Mayer Bernhard 
Published: July 2007

Chromophoric Systems, 2. – Conformation and Absorption of Light in (2‐Alkoxyvinyl)ethanedionesThe unusual color properties of yellow 1,2‐bis(4,5‐dihydrofuran‐3‐yl)ethane‐1,2‐dione (1) and colorless 1,2‐bis(5,6‐dihydro‐4H‐pyran‐3‐yl)ethane‐1,2‐dione (2) in the solid state and in solution are investigated by crystal structure analysis, UV‐Vis, PE, and 13C‐NMR spectroscopy as well as by reparameterized force‐field calculations. Dione 1 takes an antiperiplaner CO/CO conformation of its chromophore in the solid state whereas dione 2 is twisted in this respect by 102°. In solution both chromophores are not planar, but 1 is less distorted (ca. 142°) than dione 2 (ca. 126°). The calculated rotational barrier for CO/CO twisting amounts to 0.9 kcal mol−1 for 1 and to 2.2 kcal mol−1 for 2.
Synthese eines chiralen, nicht‐racemischen Aziridinons (α‐Lactams)1,2)
Authors: Quast Helmut , Leybach Holger 
Published: July 2007

Synthesis of a Chiral, Nonracemic Aziridinone (α‐Lactam)1,2)(S)‐tert‐Leucine [(S)‐14] is diazotized affording a mixture of the expected α‐chloro and α‐hydroxy acids (S)‐15 and (S)‐16 and the rearranged β‐chloro and β‐hydroxy acids (R)‐12 and (S)‐11. Separation produces a 51% yield of pure (S)‐15 (e.e. ° 97.4%) which is converted via the acid chloride (S)‐17 into the α‐chloro amides (S)‐18a and b (e.e.=99.0 and 95.2%, respectively). On treatment with tBuOK, the latter is converted into the α‐lactam (R)‐22b (59%, e.e. ° 91.0%, [α°=−293.7), which is accompanied by small amounts of its ring‐opening product (R)‐23b. Only the α‐amino ester (R)‐23 a is formed from the α‐chloro amide (S)‐18a and tBuOK. While the enantiomers of the halo amides 13, 18a, b, 24a, b and of the 3‐pentyl esters of the hydroxy acid 16 are separated by GC on chiral columns, the α‐lactam 22b and the α‐amino esters 23a, b require conversion into separable derivatives without involving the stereogenic center. Thus, alkaline hydrolysis of 22b as well as acidic cleavage of 23 yield the α‐amino acids 25 which are cyclized to the oxazolidine‐2,5‐diones 26 by means of bis(trichloromethyl) carbonate (“triphosgene”). As shown by the high enantiomeric excess of the products derived from (S)‐tert‐leucine [(S)‐14] none of the reactions described results in a considerable degree of racemization. Authentic samples of 11 and 12 are synthesized from the Reformatzky product 21. The absolute configurations of the major enantiomers derived from (S)‐14 are based on the retention on chiral GC columns, the signs of optical rotations, and CD spectra. The mechanism of the rearrangement leading to the β‐hydroxy and β‐chloro acids (S)‐11 and (R)‐12 is interpreted in terms of a stereospecific 1,2‐methyl shift occurring simultaneously with the ring cleavage of the (protonated) α‐lactone (R)‐2 (R=tBu) which is the crucial intermediate formed in the diazotization of (S)‐14.
Polylithiumorganic Compounds, XIIII. “Phospha[3]radialenes” — Reactive Intermediates in the Synthesis of “Phospha[6]radialenes”
Authors: Maercker Adalbert , Brieden Walter 
Published: July 2007

AbstractThe reaction of the dilithiobutadiene 1 with various dichloroorganylphosphanes in diethyl ether at ‐80°C leads to the formation of the novel phosphiranes 5a–e and 6a, 6c–e in up to 86% yield. A thermal isomerization of the alkenylidenephosphiranes 6 leads to the complete formation of the corresponding “phospha[3]radialenes” 5. Quaternization of the latter gives the cyclic phosphonium salts 8b–d, on addition of iodomethane, while methylation of 5a leads to the acyclic 9a. The phosphiranes 5c–e and 6c–e are converted into the bis‐ (alkylchlorophosphino)butadienes 10c–e by addition of the corresponding dichloroorganylphosphane at room temperature, whereas 5a,b and 6a are quite unreactive. The interaction of 10e with 1 gives the “phospha[6]radialene” 12e, a formal dimer of 5e. The isolated 1,4‐diphosphorinane 12e exists in a rigid trans‐chair conformation as revealed by its NMR spectra.
Gas‐Phase Kinetics of the Thermal 1‐Alkoxy‐1‐vinylcyclopropane to 1‐Alkoxy‐1‐cyclopentene Rearrangement
Authors: McGaffin Gregory , Meijere Armin De , Walsh Robin 
Published: July 2007

AbstractThe title studies have been carried out with both 1‐vinyl‐1‐cyclopropyl methyl ether (1‐OMe) and 1‐vinyl‐1‐cyclopropyl ethyl ether (1‐OEt) in the temperature ranges 274.6–324.5 and 273.6 – 323.0°C, respectively. Both reactions predominantly give the vinylcyclopropane‐cyclopentene (VCP‐CP) rearrangement products 1‐cyclopenten‐1‐yl methyl ether (2‐OMe) and 1‐cyclopenten‐1‐yl ethyl ether (2‐OEt). Additionally, 2‐OEt eliminates ethene (3) in a consecutive reaction at a lower reaction rate compared with the VCP‐CP rearrangement. The rearrangements obey first‐order kinetics and have been shown to be homogeneous, pressure‐independent reactions with the following Arrhenius equations:

The Arrhenius parameters represent reliable values for general 1‐vinyl‐1‐cyclopropyl alkyl ether→1‐cyclopenten‐1‐yl‐alkyl ether (1‐OR→2‐OR) rearrangements within a large temperature interval in the gas phase. The results support a mechanism proceeding via a diradical. The stabilizing effect of methoxy substitution is discussed.
Vinylcyclopropan‐Komplexe und Vinylcyclopropane aus Carben‐Komplexen und 1,3‐Dienen
Authors: Fischer Hemut , Hofmann Josef 
Published: July 2007

Vinylcyclopropane Complexes and Vinylcyclopropanes from Benzylidene Complexes and 1,3‐DienesBenzylidenepentacarbonyl complexes (CO)5M[C(C6H4R‐p)H] (1) [M – W:RH (a), OMe (b); MCr: R – H (c), OMe (d)], react with cyclopentadiene by stereospecific transfer of the benzylidene ligand to one CC bond of the diene and coordination of the resulting endo;‐6‐arylbicyclo[3.1.0]hex‐2‐ene (4) to the metal. The [CO]5M fragment occupies the exo‐position. Addition of bromide liberates 4 from the metal. The reaction of 1a with 1,3‐cyclohexadiene gives the corresponding (endo;‐7‐phenylbicyclo[4.1.0]hept‐2‐ene)tungsten complex (6) and, after addition of Br−, the free bicyclic compound. The sequential reaction of 1a with 1,2,3,4,5‐pentamethylcyclopentadiene and Br− affords the endo;‐6‐phenyl‐exo;‐4‐methyl isomer of pentamethylphenylbicyclo[3.1.0]hex‐2‐ene 9 with more than 85% stereoselectivity. The benzylidene transfer from 1a to cis‐and trans‐pentadiene, isoprene, and 2‐chloro‐1,3‐butadiene proceeds regiospecifically to the more electron‐rich CC bond to give (E)‐ and (Z)‐phenylvinylcyclopropanes. The E/Z ratio ranges from 0.52 to 2.2. The structures of the complexes 3d and 6 were established by X‐ray analyses.
Organosubstituierte 2,5‐Dihydro‐1,2,5‐oxoniasilaboratole Charakterisierung und Reaktivität
Authors: Köster Roland , Seidel Günter , Wrackmeyer Bernd 
Published: July 2007

Organosubstituted 2,5‐Dihydro‐1,2,5‐oxoniasilaboratoles – Characterization and Reactivity.The potassium salts of the anions (2a−d, a: R2,3 = CH3; b: R2 = C2H5, R3 = CH3; c: R2 = C6H5, R3 = CH3; d: R3 = C6H5), prepared from the organosubstituted cis;‐2‐boryl‐1‐silylalkenes 1a – d and KOH, react with the electrophiles R1Hal [R1 = H: HCl, (CH3)3NHCl; R1 = CH3: (CH3)I, (CH3)4NCl; or (CH3)3ElIV(CH3)3, ElIV=Si, Ge, Sn, Pb] to give the neutral five‐membered ring compounds [R1 = H: 3H; CH3; 3Me; ElIV(CH3)3: 3ElIV]. On heating of 3H or 3Sn either ethyl migration occurs to yield the saturated diastereomers (4) [4/4′: R3′ = H; 4Sn/4′Sn: R3′ = Sn(CH3)3], or elimination of ethane takes place to give the unsaturated compounds (5). The reaction of 2 with ClPb(CH3)3 leads to 3Pb [R1=Pb(CH3)3] (11B‐NMR), which exclusively form 5 with elimination of C2H5Pb(CH3)3.
Kohlenwasserstoffverbrückte Metallkomplexe, XVIII. Heterometallische Ethylen‐verbrückte Komplexe (OC)5ReCH2CH2Mn(CO)5, (OC)5ReCH2CH2Ru(CO)2Cp, (OC)5ReCH2CH2Os(CO)4CH2CH2Re(CO)5und (OC)5ReCH2CH2CH2Os(CO)4Os(CO)4(CO)4Os(CO)4CH2CH2Re(CO)5
Authors: Breimair Josef , Niemer Burkhart , Raab Klaus , Beck Wolfgang 
Published: July 2007

Hydrocarbon‐Bridged Metal complexes, XVIII. – Heterometallic Ethylene‐Bridged Complexes (OC)5ReCH2CH2Mn(CO)5, (OC)5ReCH2CH2Ru(CO)2Cp, (OC)5ReCH2CH2Os(CO)4CH2CH2Re(CO)5and (OC)5ReCH2CH2CH2Os(CO)4Os(CO)4(CO)4Os(CO)4CH2CH2Re(CO)5Addition of [(OC)5Re(C2H4)]+to the carbonylmetallates [Mn(CO)5]−, [RuCp(CO)2]−, [Os(CO)4]2−, [Os3(CO)12]2−affords the title complexes in a directed way. The dynamic behaviour of (OC)5ReCH2CH2Mn(CO)5in solution is attributed to a dyotropic exchange of the pentacarbonylmetal groups on the CH2CH2bridge.