bluuebunny/crossref_metadata_2025 huggingface dataset:
η2‐ und η4‐[(Dimethylamino)vinylboran]eisencarbonyl‐Komplexe
Authors: Schmid Günter , Alraun Felix , Boese Roland
Published: July 2007

η2‐ and η4‐[(Dimethylamino)vinylborane]iron Carbonyl Complexes1)

Amino‐vinylboranes can act as η2 (via the C = C bond) and as η4 ligands (via the C = C and B = N group) in iron carbonyl complexes. From bromo(dimethylamino)vinylborane and (dime‐thylamino)methylvinylborane and Fe2(CO)9 [η2‐bromo(dimethylamino)vinylborane] tetracarbonyliron (1) and tetracarbonyl[η2‐(dimethylamino)methylvinylborane]iron (2), respectively, are formed in the absence of light. The η2 coordination via the C = C group in 1 is proved by an X‐ray structure analysis. The C2BN frame is trans‐arranged. By the action of light, 1 and 2 are transferred into the very unstable tetrahapto complexes [η4‐bromo(dimethylamino)vinylborane]tricarbonyliron (3) and tricarbonyl[η4‐(dimethylamino)methylvinylborane]‐ iron (4), which can only be investigated in solution. By using tert‐butyl(dimethylamino)vinylborane the reaction leads, even in the absence of light, directly to [η4‐tert‐butyl(dimethylamino)vinylborane)tricarbonyliron (5), a compound likewise easily unstable. The transition of the η2 into the η4 complexes can be followed IR‐ and 11B‐NMR‐spectroscopically.
Synthese und flüssigkristalline Eigenschaften von Multiethern des myo‐ und scyllo‐Inosits
Authors: Marquardt Peer , Praefcke Klaus , Kohne Bernd , Stephan Werner
Published: July 2007

Synthesis and Liquid‐Crystalline Properties of myo‐ and scyllo‐Inositol Multi Ethers

Selectively alkylated myo‐ and scyllo‐inositol ethers were obtained by multi‐step syntheses starting from commercially available myo‐inositol. Necessary conversions of axial hydroxy groups into equatorial ones were achieved using either potassium superoxide (KO2) or potassium nitrite (KNO2) as oxygen nucleophiles for the transformation of myo‐ into scyllo‐ inositol derivatives. Polarizing microscopic and thermoanalytical studies of numerous members of three families (6, 13, and 20) of inositol ethers reveal for most of them thermotropic liquid‐crystalline behavior. Furthermore, in case of the two long‐chain scyllitol tetraethers 13d and e an unusual thermopolymorphism has been found. The number, position, and stereochemical arrangement of alkyl chains attached to the inositol cores strongly influence the mesogenic properties of these biomolecule derivatives, chemically vicinal diols and tetrols. The self‐assembly of the studied inositol multi ethers to columnar mesophases of “supramolecular structures” is discussed considering geometrical features of these molecules and their capabilities to aggregate by hydrogen bonding.
Mit Donorzentren versehener korbförmiger Molekülhohlraum — Darstellung, Struktur, Eigenschaften
Authors: Breitenbach Jörg , Rissanen Kari , Wolf Ute U. , Vögtle Fritz
Published: July 2007

Basket‐shaped Molecular Cavity‐Containing Donor Centres — Synthesis, Structure, Properties

The macrocyclic basket‐shaped molecule 2, composed of three 4‐donor‐substituted pyridine units, is synthesized by cyclisation of the chloromethyl compound 7 with sulfonamide 8. The X‐ray structure analysis of 2 gives an impression of the shape of the molecular basket. Furthermore it demonstrates that the toluenesulfonamide residues interlink, creating dimeric units of 2 in the crystal.
Organische Synthesen mit Übergangsmetallkomplexen, 53 4‐Methylencyclopentene und 5‐Methylencyclohexenone aus „Fischer‐Carben”︁‐ Chromkomplexen, Allenen und Alkine
Authors: Aumann Rudolf , Trentmann Beate
Published: July 2007

Organic Syntheses via Transition Metal Complexes, 53. — 4‐Methylenecyclopentenes and 5‐Methylenecyclohexenones from “Fischer Carbene” Chromium Complexes, Allenes, and Alkynes

A method is described for the two‐step construction of 4‐methylenecyclopentenes 6 and 5‐methylenecyclohexenones 7 from Fischer carbene chromium complexes, allenes, and alkynes. In the first step a tri(methylene)methane complex 3 is generated by the addition of the carbene chromium complex (CO)5Cr = C(0Et)Ph (1) to the allene 2. The second step involves an addition of 3 to alkynes HC≡CR [5: R = Ph (a), SiMe3 (b)] at 75°C to give 6 and/or 7 in high chemical yields. The product ratios strongly depend on the substituents R.
Highly Efficient Hydroxylation of Carbonyl Compounds with Dimethyldioxirane
Authors: Adam Waldemar , Prechtl Frank
Published: July 2007

The enolates and/or enols of ketones, esters, β‐diketones, β‐oxo esters, and β‐oxo lactones were transformed by dimethyl‐dioxirane (isolated in acetone solution or generated in situ) into their α‐hydroxy compounds in good to excellent yields. The direct hydroxylation of the enols was significantly enhanced by the use of fluoride ion. For the enolate of camphor the exo/endo diastereoselectivity depended significantly on the metal ligand; the highest exo/endo ratio (93:7) was observed for the enol trimethylsilyl ether of camphor.
Notiz/Note Zur Stereochemie der Reaktion von Vinylhalogeniden mit Perchlorcyclopentadien: Cycloaddition über Vinylkationen
Authors: Buddrus Joachim , Preut Hans
Published: July 2007

The Stereochemistry of the Reaction between Vinyl Halides and Perchlorocyclopentadiene: Cycloaddition via Vinyl Cations

In the presence of aluminium chloride vinyl halides react with perchlorocyclopentadiene to yield stereoselectively bicyclic compounds (e.g. 2a), the structure of which is determined in two cases (2a, b) by X‐ray analysis. Vinyl cations are proposed as intermediates.
Isocyanatosulfonium‐Salze
Authors: Erhart Markus , Mews Rüdiger , Pauer Frank , Stalke Dietmar , Sheldrick George M.
Published: July 2007

Isocyanatosulfonium Salts

RR'SF2 reacts with Me3SiNCO to give the corresponding N‐(fluoroformyl)sulfur imides FC(O)NSRR' [R = NMe2, R' = F (7); R' = CF3 (9)]. From these AsF5 abstracts F‐ with formation of isocyanatosulfonium salts ONC—SRR' + AsF‐6 [R = F, R' = CF3 (6); R = NMe2, R' = F (8); R = NMe2, R' = CF3 (10)]. The spectroscopic properties of the fluoroformyl derivatives and of the isocyanato salts are discussed. The structures of 8 and 10 are determined by X‐ray analyses.
η4‐Complexes of 4,7‐Dihydroacepentalene: Facile Degenerate Haptotropic Rearrangement of (η5‐Cyclopentadienyl)(η4‐4,7‐dihydroacepentalene)cobalt(I) in Contrast to its Tricarbonyliron Counterpart
Authors: Schröder Günter , Butenschön Holger , Boese Roland , Lendvai Tomas , Meijere Armin De
Published: July 2007

The (cyclopentadienyl)cobalt(I) complex 4 of the 4,7‐dihydroacepentalene

The numbering of the ring system corresponds to the tricyclo‐decatetraene nomenclature used in the Exp. Part. Thus, 4,7‐substitution would be 2a,4a‐substitution in acepentalene numbering.

derivative 2b has been prepared by the reaction of the ligand with (cyclopentadienyl)bis(ethene)cobalt(I). NOE experiments indicate a complexation at the convex face of the polyolefinic ligand. 1H‐NMR spectra establish a degenerate haptotropic rearrangement with CpCo migration from one diene unit to the adjacent one. The activation energy of this process is estimated to be 15 kcal/mol. An X‐ray crystal structure determination of (η4‐4,7‐dihydroacepentalene)tricarbonyliron derivative 3a shows a distorted coordination of Fe(CO)3 at the convex face of the ligand, too.
Metallkomplexe mit biologisch wichtigen Liganden, LXIII Aspartam als dreizähniger Ligand in metallorganischen Komplexen: Darstellung und Struktur von Cp*Rh[O2CCH2CH(NH2)C(O)NCH(CH2Ph)CO2Me]
Authors: Krämer Roland , Polborn Kurt , Beck Wolfgang
Published: July 2007

Metal Complexes of Biologically Important Ligands, LXIII1). — Aspartame as Tridendate Ligand in Organometallic Complexes: Preparation and Structure of Cp*Rh[O2CCH2CH(NH2)C(O)NCH(CH2Ph)CO2Me]

Aspartame reacts with [Cp*RhCl2]2 in the presence of base to give the title complex 1 with the deprotonated tridendate dipeptide ester as ligand.
Kohlenwasserstoffverbrückte Metallkomplexe, XXII1) Addition von anionischen Fischer‐Carben‐Komplexen an koordinierte ungesättigte Kohlenwasserstoffe unter C – C‐Kupplung
Authors: Breimair Josef , Weidmann Torsten , Wagner Barbara , Beck Wolfgang
Published: July 2007

Hydrocarbon‐Bridged Metal Complexes, XXII1). – Addition of Anionic Fischer Carbene Complexes to Coordinated Unsaturated Hydrocarbons with C – C Coupling

The addition of [(OC)5MC(OMe)CH2]– (M = Cr,W) to the cationic complexes [(OC)5Re(C2H4)]+ and [(OC)3M' (λ7‐C7H7)]+ (M' = Cr, Mo) affords the bimetallic hydrocarbon‐bridged complexes (OC)5M = C(OMe)CH2CH2CH2Re(CO)5 (1) and (OC)5M = C(OMe)CH2C7H7 – λ6 – M'(CO)3 (2), respectively. The structures of 1a and 2d have been determined by X‐ray diffraction.
Reaktionen der Azadiboriridine: Clusterbildung und Ringerweiterung
Authors: Paetzold Peter , Redenz‐Stormanns Burkhard , Boese Roland
Published: July 2007

Reactions of the Azadiboriridines: Formation of Clusters and Ring Expansions*

Nine bis(haloboryl)amines 1 were synthesized by haloboration of iminoboranes RB = NR” with dihaloboranes R'BHal2 [R/R'/R” = Et/iPr/tBu (1b), Et/sBu/tBu (c), iPr/iPr/iPr (d), iPr/tBu/iPr (e), tBu/Me/tBu (g), tBu/Et/tBu (h), tBu/Et/SiMe3 (k), tBu/tBu/SiMe3 (1), tBu/Cl/tBu n)]. The borane 1n can be transformed into 1o (R' = NMe2) by the reaction with Me3SiNMe2; an equilibrium between 1o and the four‐membered ring 1o' is observed, 1o' being formed from 1o by intramolecular B – N coordination. On reduction with lithium, the nido‐diazahexaboranes 3b–e, g, h are formed from the corresponding bis‐(haloboryl)amines 1. In the case of 3e, g, h, the ligands R and R' are unsymmetrically distributed to axial and equatorial positions of the fragment structure derived from the pentagonal bipyramid. In particular cases, azadiboriridines of type 2 are either isolated or proven as intermediates on the way from 1 to 3. The three‐membered ring of the known azadiboriridines 2i, m (R/R'/R” = tBu/iPr/tBu, tBu/tBu/tBu) is expanded to the five‐membered ring of the corresponding azadiborolines 4i, m by the reaction with 3‐hexyne. The products 4i, m are reduced to the dilithium azadiborolinates 5i, m by the action of lithium; the molecular structure of a closo‐azadicarbadili‐thiaheptaborane is recognized in crystals of 5i. The threemembered ring of 2m is also expanded by the reaction with the iminoborane EtB ≡ NtBu giving the diazatriborolidin 6m, which crystallizes in the space group Pca21
Komplexchemie perhalogenierter Cyclopentadiene und Alkine, VII Darstellung einiger Tetrachlormetallole von Cobalt, Rhodium und Iridium; Struktur eines Iridacyclopentadien‐Derivats
Authors: Siinkel Karlheinz
Published: July 2007

Coordination Chemistry of Perhalogenated Cyclopentadienes and Alkynes, VII1). – Synthesis of Several Tetrachlorometalloles of Cobalt, Rhodium, and Iridium; Structure of a Iridacyclopentadiene Derivative

The reaction of dichloroethyne with CpCo(PPh3)2, RhCl(EPh3)3 (E = P, As, Sb), and IrCl(N2)(PPh3)2 leads to the formation of complexes containing a tetrachloro‐1‐metallacyclopentadiene unit. The crystal‐structure determination of (Ph3P)2(Cl)‐ is reported.
Photochemische Mitteilungen, 76 Studien im Umfeld der Oxanorbornadien → Oxepin‐Isomerisierung. Eine intramolekulare Dien/Enon‐[4 + 2]‐Photocycloaddition
Authors: Wollenweber Markus , Fritz Hans , Prinzbach Horst , Rihs Grety
Published: July 2007

Photochemical Transformations, 761). – Studies in the Area of the Oxanorbornadiene → Oxepine Isomerization. An Intramolecular Diene/Enone [4 + 2] Photocycloaddition

At room temperature, the “tropone‐annulated” oxanorborna diene 2b dimerizes regio‐ and stereospecifically to give a [6 + 4] adduct (5). Direct photoexcitation of this adduct induces intramolecular diene/enone [4 + 2] addition to 16 followed by a [2 + 2] cycloaddition to provide the dodecacycle 17. An X‐ ray crystal structure analysis of 17 documents the influence of the heteroatom and of the quasi‐bisected ester functions on the length of the three types of oxaquadricyclane – three‐membered ring bonds. Direct and sensitized excitation of 2b, c produces polymers; yet, after changing the troponoid chromophor (9, 10) oxaquadricyclane formation takes place (13, 14). In the thermolysis of the annulated oxaquadricyclanes (13, 14) the different cyclopropane C – C bonds are cleaved at a comparable rate.
Studien zur enantio‐ und diastereoselektiven α‐Metallierung prochiraler Sulfoxide mit (+)‐Menthyllithium
Authors: Maercker Adalbert , Schuhmacher Rudolf , Buchmeier Willi , Lutz Heinz Dieter
Published: July 2007

Enantio‐ and Diastereoselective α‐Metallation of Prochiral Sulfoxides by (+)‐Menthyllithium

Six out of ten prochiral dialkyl sulfoxides 3 with diastereotopic α methylene protons were stereoselectively metallated by (+)‐menthyllithium (11) to yield two diastereomeric pairs of enriched enantiomers 29 after the reaction with benzophenone. The maximum e.e. was 40%. Dicyclohexyl sulfoxide (3c) was deprotonated enantioselectively with an e.e. of 30%. 2‐Bornyllithium (21) was unsuccessful as a chiral base and was shown for the first time to contain 4% of isobornyllithium (22). The reactions were performed in pentane at – 80°C; in diethyl ether and THF the e.e.'s were only slightly higher, and at higher temperatures the selectivity was rapidly decreasing. It was shown that racemization takes place by an intermolecular transmetallation reaction. The structure of 29f [n = 3] was elucidated by an X‐ray analysis.
Organic Electron Transfer Systems, II Substituted Triarylamine Cation‐Radical Redox Systems – Synthesis, Electrochemical and Spectroscopic Properties, Hammet Behavior, and Suitability as Redox Catalysts
Authors: Dapperheld Steffen , Steckhan Eberhard , Brinkhaus Karl‐Heinz Grosse , Esch Thomas
Published: July 2007

21 triarylamines (1n – 1z, 1za, 1zb) and triarylamine analogs (2a, 2b, 3a, 3b, 4a, 4b) with substituents in at least all three p positions and some of their cation‐radical hexachloroantimonates have been synthesized. The electrochemical behavior has been studied by cyclic voltammetry. Most of the compounds show chemically and electrochemically reversible first oxidation waves in the formation of the cation radicals. With the exception of 4a and 4b, the second wave for the formation of the dication is chemically irreversible. The UV spectra of the triarylamine cation radicals have been obtained in the presence of a slight excess of SbCl5. A good Hammett correlation between the first anodic potential of only p‐substituted triarylamines and the σ/σ values has been established. Some redox‐catalytic properties of triarylamine cation radicals are described.
7,15‐Dihydroxy[2.2](2,6)pyridinophan: Darstellung über selenoorganische Stufen und Aggregation durch Wasserstoff‐Brückenbindungen
Authors: Breitenbach Jörg , Nieger Martin , Vögtle Fritz
Published: July 2007

7,15‐Dihydroxy[2.2](2,6)pyridinophane: Synthesis via Organoselenium Compounds and Aggregation by Hydrogen Bonds*

7,15‐Dihydroxy[2.2](2,6)pyridinophane (5) was prepared by using dimethoxy‐diselena[3.3]pyridinophane 3 as a precursor. The X‐ray structural analyses of both phanes (5 x 2 HI x 2 DMSO and 3), show the extremely syn‐shaped [3.3]phane 3 and the [2.2]phane 5 with antagonistically hydrogen‐bonded solvent molecules.
Organische Synthesen mit Übergangsmetall‐Komplexen, 55 5‐Aza‐1‐metalla‐1,3,5‐triene von Chrom und Wolfram sowie deren Cyclisierung zu 2H‐Pyrrol‐Komplexen
Authors: Aumann Rudolf , Heinen Heinrich , Goddard Richard , Krüger Carl
Published: July 2007

Organic Syntheses via Transition Metal Complexes, 551). – 5‐Aza‐1‐metalla‐1,3,5‐trienes of Chromium and Tungsten, and Their Cyclization to 2H‐Pyrrole Complexes

5‐Aza‐1‐metalla‐1,3,5‐trienes 5 and 6 [LnM = C – C = C – N = C, a: LnM = Cr(CO)5, b: W(CO)5] are obtained in two steps from aminocarbene complexes 1 [LnM = C(NH2)Ph, a: LnM = Cr(CO)5, b: W(CO)5]. The first step involves the condensation of 1 with benzaldehyde (2) in the prescence of TiCl4/Et3N to give 3‐aza‐1‐metalla‐1,3‐dienes 3 (LnM = C – N = C). 3 adds to the 1‐aminoalkyne 4 to give 5 and 6 by a chain extension of two carbon atoms. The trans isomers 5 are formed as the major products and are stable both in the solid state and in solution. The cis isomers 6 undergo a novel‐type cyclization to give 2H‐pyrrole complexes 8. Triene 5b was characterized by an X‐ray analysis.
HCl‐Abspaltung aus Ethansulfenylchlorid und Chlordimethylsulfid
Authors: Maier Günther , Flögel Ulrich , Reisenauer Hans Peter , Andes Jr. B. Hess, , Schaad Lawrence J.
Published: July 2007

HCl Elimination from Ethanesulfenyl Chloride and Chlorodimethyl Sulfide

Thioacetaldehyde (5) is prepared by matrix photolysis of ethanesulfenyl chloride (3) or thiirane (4) and by flash pyrolysis of allyl ethyl sulfide (6). Matrix irradiation of 3 or 5 with 222‐nm light results in a dehydrogenation, and a mixture of thiirene (7), ethynethiol (8), and thioketene (9) is formed. Flash pyrolysis of chlorodimethyl sulfide (1) yields ethenethiol (11) together with thiirane (4), whereas ethanesulfenyl chloride (2) gives ethene under the same conditions. The identification of thioacetaldehyde (5) is based on the comparison between the experimental and calculated IR spectra.
Wasserstoffübertragungen, 17 Elektronentransfer‐induzierte Aromatisierung von 1,4‐Dihydronaphthalin durch Tris(4‐bromphenyl)aminiumyl‐Ionen
Authors: Giese Georg , Heesing Albert
Published: July 2007

Hydrogen Transfer Reactions, 171). — Electron‐Transfer‐Induced Aromatization of 1,4‐Dihydronaphthalene by Tris(4‐bromophenyl)aminiumyl Ions

The first step in the aromatization of 1,4‐dihydronaphthalene (1) by the radical cation 2 of tris(4‐bromophenyl)amine (3) is a rapid electron transfer in an equilibrium completely shifted to the side of the substrates. The deprotonation of the radical cation 7 of 1,4‐dihydronaphthalene is rate‐determining as shown by both cyclovoltagrams and isotope effects of deuterated hydrogen donors.
A New Access to Sterically Shielded Allenes
Authors: Krause Norbert
Published: July 2007

The synthesis of the sterically shielded allenes 2 and 5 by 1,6‐and 1,4‐addition of organocuprates to acceptor‐substituted enynes and diynes, respectively, is described. Treatment of the di‐tert‐butyl‐substituted allenes 2 with aqueous base does not cause double bond isomerization; whereas ester 2a is converted into the corresponding β‐allenic acid, ketone 2b yields the 2H‐pyran 6.
Anticancer Agents, 17 1,4‐Disila[6]radialene: Aktivierungsparameter der Sessel‐Twist‐Inversion und analytische Enantiomerentrennung der Twist‐Konformeren
Authors: Tietze L. F. , Krach T. , Beller M. , Arlt M.
Published: July 2007

A New Highly Efficient Method for the Synthesis of 1'‐Alkyl‐ and 1'‐Phenyl‐Substituted Pyrimidine Acyclonucleosides
1,2,3‐Triborolane aus Norbornenderivaten, Allylbenzol und Dehalogenierungsprodukten von Dichlor(diisopropylamino)boran; 2,4,5‐Tris(diisopropylamino)‐2,4,5‐triborabicyclo[1.1.1]pentan‐Bicyclus oder Carboran?
Authors: Bromm Dietmar , Seebold Uwe , Noltemeyer Mathias , Meller Anton
Published: July 2007

1,2,3‐Triborolanes from Norbornene Derivatives, Allylbenzene and Dehalogenation Products of Dichloro(diisopropyl‐amino)borane; 2,4,5‐Tris(diisopropylamino)‐2,4,5‐triborabicyclo[1.1.1]pentane‐Bicyclus or Carborane?

The new 1,2,3‐tris(diisopropylamino)triborolanes 1, 2, 3 and 4 have been prepared by treatment of mixtures of 2‐norbornene (A), 5‐methylene‐2‐norbornene (B), 5‐ethylidene‐2‐norbornene (C) and allylbenzene (D) with dichloro(diisopropylamino)borane with Na/K alloy in hexane. The corresponding species 5, derived from 2,5‐norbornadiene (E), is relatively unstable and by a retro Diels‐Alder reaction gives 2,3,4‐tris(diisopropylamino)‐1,5‐dicarba‐closo‐pentaborane(5) (6). The compounds are characterized by chemical analyses, MS and NMR (1H, 11B, 13C, 15N) and 1, 4 and 6 also by X‐ray structure analyses.
1,3‐Bis[tert‐butyl(di‐tert‐butylfluorsilyl)amino]trisulfan – eine Verbindung mit FSiNSSSNSiF‐Helix
Authors: Klingebiel Uwe , Pauer Frank , Sheldrick George M. , Stalke Dietmar
Published: July 2007

1,3‐Bis[tert‐butyl(di‐tert‐butylfluorosilyl)amino]trisulfane – a Compound with FSiNSSSNSiF Helix

The lithium derivative of tert‐butyl(di‐tert‐butylfluorosilyl)‐amine (1) reacts with sulfur or selenium to give the bis[(fluorosilyl)‐amino]di‐ and ‐trisulfanes 2, 3 and ‐selane 4, respectively. The trisulfane 3 crystallizes from n‐hexane and exhibits a helical structure (X‐ray analysis).
1,6‐Heptadien‐Nickel(0)‐Komplexe: rac/meso‐(μ‐η2,η2‐C7{Ni( η2,η2‐C7H12)}2 und L‐Ni(η2,η2‐C7H12)
Authors: Proft Bernd , Pörschke Klaus‐Richard , Lutz Frank , Krüger Carl
Published: July 2007

1,6‐Heptadiene Nickel(0) Complexes:rac/meso‐(μ‐η2,η2‐C7{Ni(η 2,η2‐C7H12)}2 und L‐Ni(η2,η2‐C7H12)

Ni(CDT) dissolves in 1,6‐heptadiene with displacement of the CDT to yield the dinuclear homoleptic product rac/meso‐(μ‐ η2,η2‐C7H12){Ni(η2, η2‐C7H12)}2 (1) as a mixture of stereoisomers, in which the nickel atoms are trigonal‐planar coordinated by a chelating 1,6‐diene ligand and one CC bond of a bridging diene ligand. The stereoisomers differ in the coordination mode of the bridging diene ligand.‐The bridging diene ligand in 1 can be displaced by various donor/acceptor molecules. In pentane, 1 reacts with ethene to yield a solution of mononuclear (C2H4)Ni(η2,η2‐C7H12) (2). With alkynes unstable complexes are formed of which the anticipated ethyne derivative (C2H2)Ni(η2,η2‐C7H12) (3) decomposes explosively at – 100°C. With isocyanides, methylenephosphoranes, methyllithium, amines, pyridines, phosphanes, and phosphites (i.e. C, N, P donors) crystalline complexes of type L‐Ni(η2.η2 C7H12) have been obtained, of which the derivatives with L=tBuN  C 4, Me3PCH2 5, LiCH3 6, C7H13N7, C5H5N 8, Me3P 9, iPr3P 10, Ph3P 11, (PhO)3P 12 are characterized here. For 11 the crystal structure has been determined.
Synthesis and Reactions of P‐Supermesityl‐C‐halophosphaalkenes
Authors: Goede Simon J. , Bickelhaupt Friedrich
Published: July 2007

C‐Halophosphaalkenes (1, 2) were prepared in high yield by a one‐pot synthesis from HCX3 or CI4 and Mes* PCl2 (Mes*  supermesityl  2,4,6‐tri‐tert‐butylphenyl). The C‐iodophosphaalkenes Mes* P  Cl2 (1 C) and Mes*P  CHI (2c) undergo halogen‐metal exchange with n‐BuLi at low temperatures. The resulting carbenoids Mes*P  CILi (11 c) and Mes*P  CHLi (6) reacted with ClMMe3 (M  Si, Ge, Sn) to give Mes*PCIMMe3 [(Z)‐13: M  Ge; (Z)‐14: M  Sn] or Mes*P  CHMMe3 (8–10), respectively. Further reaction of (Z)‐13 and (Z)‐14 with nBuLi and ClMMe3 gave Mes*PC(MMe3 (18: MGe; 19: M  Sn). The carbenoid (Z)‐11 c decomposed at −85°C; instead of the expected “phosphaisonitrile” Mes*P  C : (21), only Mes*CP (15) was obtained which lends experimental support to the theoretically predicted instability of 21.
Azoalkan‐ und Nitren‐verbrückte Carbonylmetall‐Cluster des Eisens und Rutheniums
Authors: Hansert Bernhard , Powell Anne K. , Vahrenkamp Heinrich
Published: July 2007

Azoalkane‐ und Nitrene‐Bridged Carbonyl Metal Clusters of Iron and Ruthenium

By using cluster buildup reactions, the new azoalkane‐bridged clusters Ru3(CO)9(RNNR) (3a, RMe, 3b, REt), Fe2Ru(CO)9(EtNNEt) (4), Ru4(CO)12(RNNR) (5a, RMe, 5b, REt), and FeRu3(CO)12(EtNNEt) (6) were obtained. Upon attempts to prepare further such compounds, the N‐N bond was cleaved resulting in nitrene‐bridged clusters including the new compound Fe4(CO)11(μ4‐NEt)2 (9). Cluster buildup starting from Ru3(CO)9(μ3‐NPh)2 resulted in Ru4(CO)11(μ4‐NPh)2 (10) and FeRu3(CO)11(μ4‐NPh)2 (11). The crystal structures of 5b and 9 as well as some reactions of the nitrene‐bridged clusters are described.
Verbindungen mit dem 2,4‐Dimethyl‐2,4‐diaza‐1,5‐diphosphapentan‐3‐on‐Grundgerüst; Synthese, Struktur und Eigenschaften von 1,5‐Di‐tert‐butyl‐2,4‐dimethyl‐1,5‐diphenyl‐2,4‐diaza‐l,5‐diphosphapentan‐3‐on und Derivaten
Authors: Vogt Roland , Jones Peter G. , Schmutzler Reinhard , Kolbe Alfred
Published: July 2007

Compounds with the 2,4‐Dimethyl‐2,4‐diaza‐1,5‐diphosphapentan‐3‐one Skeleton; Synthesis, Structure, and Properties of 1,5‐Di‐tert‐butyl‐2,4‐dimethyl‐1,5‐diphenyl‐2,4‐diaza‐1,5‐diphosphapentan‐3‐one and Its Derivatives

N,N′‐Dimethyl‐N‐N′‐bis(trimethylsilyl)urea (1) reacts with tert‐butylchlorophenylphosphane (2) to form the monophosphino/ trimethylsilyl‐substituted urea 3. Under more vigorous conditions the bisphosphino‐substituted derivative 4 was also obtained. The reaction of 4 with the tetracarbonyl norbornadiene derivatives of Cr, Mo, and W furnished the unusual chelate complexes 5–7, in which the ligand 4 is coordinated to the metal through one of the two phosphorus atoms and the oxygen atom of the carbonyl group. The free ligand 4 and the isostructural complexes 5 and 6 were subjected to X‐ray structure analyses. The approximate twofold symmetry of 4 is lost as a result of a major conformational change on complex formation. In contrast, 4 reacts with Fe2(CO)9 and with (COD)‐PtCl2 (COD=1,5‐cyclooctadiene) to give the complexes 8 and 9. In both 8 and 9 the ligand 4 is coordinated by both phosphorus atoms. Reaction of 4 with sulfur and selenium led to the disulfide 10 and diselenide 11, whereas with tellurium no reaction was observed.
Decaethyl‐2,6,8,10‐tetracarba‐nido‐decaboran(10) – Herstellung, Struktur im festen Zustand und Stabilität(1)
Authors: Köster Roland , Seidel Günter , Wrackmeyer Bernd , Bläser Dieter , Boese Roland , Bühl Michael , Schleyer Paul Von Ragué
Published: July 2007

Decaethyl‐2,6,8,10‐tetracarba‐nido‐decaborane(10) – Preparation, Structure in the Solid State, and Stability[1]

The title compound 6, prepared in two steps from the pentaethyl‐1,5‐dicarba‐closo‐pentaborane(5) (1), is characterized at 103 K as the low‐temperature solid phase LT‐6 by a single‐crystal X‐ray structure analysis; 6 reacts with alkali metals (K, Cs) to form the C4B6Et10 dianion (62–) which is easily oxidized to 6 (e.g. with I2, FeCl2, HgCl2). Ab initio MO and IGLO calculations of compound 6 have been carried out.
Carbonyl(η5‐cyclopentadienyl)(trimethylphosphan)[η2‐(methylthio)‐phenylcarben]molybdän‐tetrafluoroborat – ein amphiphiler Carbenkomplex
Authors: Kreißl Fritz R. , Stegmair Claudia M.
Published: July 2007

Carbonyl(η5‐cyclopentadienyl)(trimethylphosphane)[η2‐(methylthio)phenylcarbene]molybdenum Tetrafluoroborate – an Amphiphilic Carbene Complex

The title complex 1 adds the electrophile SMe+ as well as the nucleophilic PMe3 at the carbene carbon to form the complexes 2 and 3, respectively.
Synthesis of Novel Bispyrimido[1,2‐b:1′,2′‐e][1,2,4,5]tetrazines
Authors: Liebscher Jürgen , Riemer Beate , Hassoun Ahmed , Stöβer Reinhard , Grubert Lutz
Published: July 2007

Novel bispyrimido[1,2‐b:1′,2′‐e][1,2,4,5]tetrazines 3 are obtained by self‐condensation of 1‐amino‐2‐(methylthio)pyrimidinium iodides 1. Zwitterionic bispyrimidines act as intermediates and can be isolated after short heating. Compounds 3 are oxidized with bromine or perchloric acid in acetic acid to give the corresponding radical salts 4. These very stable radicals are characterized by ESR spectra and by cyclic voltammetry.
Reduktive Umwandlungen, 18(2) Cycloanellierung und Überbrückung von Cyclooctatetraen(1)
Authors: Auchter‐Krummel Petra , Krummel Günter , Müllen Klaus , Lex Johann
Published: July 2007

Reductive Transformations, 18[2]. – Cycloannulation and Bridging of Cyclooctatetraene[1]

Reductive alkylations of cyclooctatetraene (1) with biselectrophiles have hitherto been described as proceeding solely under 1,2‐cycloannulation. Using different alkylating agents with varying chain lengths, conformational mobility, and leaving groups we succeeded in achieving regio‐ and stereoselective reactions of the intermediate monoalkyl monoanion 3. By systematic variation of the biselectrophiles the subtle competition of 1,2‐ versus 1,4‐ and of 1,n‐cis‐ versus 1,n‐trans‐cyclization is elucidated. It is shown that the regio‐ and stereoselectivity are controlled mainly by the structure of the alkylating reagents while other parameters such as solvent or leaving group do not play an important role. Reductive alkylation of 1 provides an easy access to a large number of compounds which may be oxidized to new cyclooctatetraene systems or serve as substrates for further skeletal rearrangements. – X‐ ray structure analyses are performed for compounds 15, 27 a, 28, and 29.
Small and Medium Rings, 781) Cage Dimers of Norbornadiene with Perpendicular Arrangement of Subchromophores: Orbital Interaction in the Heptacyclo[6.6.0.02,6.03,13.04,11.05,9.010,14]tetradecane System
Authors: Albert Bernhard , Elsässer Dominik , Martin Hans‐Dieter , Mayer Bernhard , Chow Tahsin J. , Marchand Alan P. , Ren Chien‐Tai , Paddon‐Row Michael N.
Published: July 2007

The syntheses of functionalized norbornadiene dimers 1 are described. These cage compounds feature remarkably high D2d symmetry as regards the dimethylene and dioxo derivatives 1d and 1e. On the other hand, the mixed enone compound 11 behaves differently: πcc and lone‐pair nco orbitals mix strongly with each other, albeit only by means of the intervening five‐bond σ system. All theoretical conclusions have been verified by using PE spectroscopy. A comparison is made between systems 1 and the geometrically similar adamantanes 2, on the one hand, and the attractive but still unknown derivatives of garudane 3 on the other hand. The latter exhibit the interesting parallel topology of suitable chromophores, thus making these polycycles 3 desirable candidates for transmission studies.
Oxidative Trimerisierung von Alkinylgruppen an Trimethylphosphan‐Palladium‐Komplexen
Authors: Klein Hans‐Friedrich , Zettel Bernd , Flörke Ulrich , Haupt Hans‐Jürgen
Published: July 2007

Oxidative Trimerization of Alkynyl Groups at Trimethylphosphane Palladium Complexes

Alkynylpalladium halides trans‐PdX (C ≡ CR)(PMe3)2 [1, 2, 4, X = Cl, R = SiMe3, (CH2)2CH3, (CH2)5CH3; 3, X = Br, R = (CH2)2CH3] were synthesized by routine methods, while further examples of the series trans‐PdX (C ≡ CR)(PMe3)2 [5, 7, 8, 10, X = Br, R = SiMe3, CMe3, (CH2)2CH3, Ph; 7, 9, 11, X = I, R = SiMe3, SiPh3, OEt] and trans‐PdX (C ≡ CR)(PPh3)2 (12‐14, X=I, R=SiMe3, CMe3, CH2OH) were obtained by oxidative addition of 1‐halogeno‐1‐alkynes to PdL4 (L=PMe3, PPh3). Just above the melting point or decomposition point 5‐7 are transformed by oxidative trimerization of the alkynyl groups to give enediynyl complexes trans‐PdX[C(C ≡ CR)=C(C ≡ CR)R](PMe3)2 (15, 16, R=SiMe3, X=Br, I; 17, X=Br, R=CMe3). According to an X‐ray structure analysis 17 has E configuration.
Trinuclear Homo‐ and Heterometallic Complexes of a Doubly Bridged Cyclopentadienyl Ligand
Authors: Siemeling Ulrich , Jutzi Peter
Published: July 2007

Metal complexes that are derived from the doubly bridged cyclopentadiene system 2,2,8,8‐tetramethyl‐2,8‐disilatricyclo[7.3.0.03,7] dodeca‐3,5,9,11‐tetraene (LH2) are investigated. The dilithio salt of this compound (LLi2) reacts with (Me3Si)3‐C5H2FeCl to give, amongst other products, the trinuclear ferrocene [(Me3Si)3C5H2FeL]2Fe (2). A starting material well suited for the selective preparation of similar trinuclear complexes is the mononuclear ferrocene (HL2)Fe (3) which is formed by reaction of HLLi with iron(II) chloride. Reaction of dilithiiated 3 with trimethyltin chloride yields (Me3SnL)2Fe (4). Cocomplexation of dilithiated 3 and Cp*Li (Cp*=C5Me5) with iron(II) chloride leads to the trinuclear ferrocene (Cp*FeL)2Fe (5). By reaction of 3 with octacarbonyldicobalt the heterometallic complex [(CO)2CoL]2Fe (6) is obtained, which yields [(CO)I2CoL]2Fe (7) by oxidative decarbonylation with iodine. The stereochemistry of the complexes presented is discussed. The trinuclear complexes 2, 5, 6, and 7 are model systems for organometallic polymers with spatially directed structures, whose stability even in mixed‐valence states is evidenced by the mass spectra of these complexes.
Synthese, Struktur und Reaktivität eines Stanna(II)‐nickela(II)‐cyclobuten‐Komplexes
Authors: Pluta Christian , Pörschke Klaus R. , Ortmann Ingo , Krüger Carl
Published: July 2007

Synthesis, Structure, and Reactivity of a Stanna(II)‐nickela(III)‐cyclobutene Komplexes

The (ethyne)nickel(0) complex (iPr2PC2H4PiPr2)Ni(C2H2) (1) reacts with the stannene Sn[CH(SiMe3)2]2 below −30°C to yield the stanna(II)‐nickela(II)‐cyclobutene complex (iPr2PC2H4PiPr2)YYNiCH=YYCHSn[CH(SiMe3)2]2 (2; 83%) as the kinetically controlled product; 2 has been characterized by IR and NMR spectroscopy and an X‐ray crystal‐structure determination. The latter shows the central four‐membered ring to be planar with a long Ni—Sn bond [2.626(1) Å]. According to the temperature‐dependent NMR spectra, 2 dissociates reversibly in solution to the starting components. The synthesis reaction thus represents an equilibrium as long as the temperature is below 20°C. These observations indicate that the structural lability of the stanna(II)‐nickela(II)‐cyclobutene moiety is associated with the weakness of the Ni—Sn bond. The bonding situation in 2 is best described as an “inner complex” in which a stannyl anion is coordinated to a nickel(II) cation. An ethereal solution of 2 undergoes an oxidative addition of one ethyne C—H bond to the stannene at 20°C to give the Ni(0)/Sn(IV) complex iPr2PC2H4PiPr2)Ni({η2‐HC≡CSn(H)[CH(SiMe3)2]2} (3) as the thermodynamically controlled product. Reaction of 3 with CO liberates the new alkyne ligand.
Elektroreduktion organischer Verbindungen, 19 Bildung benzoanellierter Schwefelheterocyclen durch intramolekulare kathodische Cyclisierung von Dithiocarbonsäureestern
Authors: Gade Thomas , Streek Michael , Voß JüRgen
Published: July 2007

Electroreduction of Organic Compounds, 19. — Formation of Benzoanellated Sulfur Heterocycles by Intramolecular Cathodic Cyclization of Dithiocarboxylic Esters

Cathodic reduction of aryl (3) and benzyl (5) dithiopivaloates and related dithioesters with leaving groups at the benzene ring or a side chain yield the sulfur heterocycles 23, 30—32, and 34 depending on the nature of the starting material and the reaction conditions. In case of the α‐oxo‐dithioester 22, thioindigo (44) is formed. — The corresponding thioamides 14, 16, and 18 show a strong tendency to reductive dehalogenation but the S,N‐heterocycles 38 and 39 are also formed in minor amounts. — The formation of the rearranged products 29—32, and 34 is discussed in terms of C,S‐splitting in the primarily formed radical anion and subsequent C,C‐coupling of the fragments and follow‐up reactions.
Übergangsmetallaktivierte organische Verbindungen, XXXV. Ortho‐Alkylierungen von aromatischen Azoverbindungen mit Alkyllithium‐Reagenzien und Lithiumtrimethylferrat(1‐)
Authors: Kauffmann Thomas , Jordan Jan , Sander Jörg
Published: July 2007

Transitional‐Metal‐Activated Organic Compounds, XXXV. — ortho‐Alkylation of Aromatic Azo Compounds with Alkyllithium Reagents and Lithium Trimethylferrate(1‐)

Whereas methyllithium reacts with 4‐(dimethylamino)‐, 4‐amino‐, and 4‐methoxyazobenzene, respectively, by ortho‐methylation of the electron‐rich phenyl residue of the azo compound, (CH3)3FeLi ortho‐methylates the less electron‐rich phenyl group of 4‐(dimethylamino)azobenzene. A mechanistic rationalisation is given for both reaction modes.
Untersuchungen zur Chemie von Isoindolen und Isoindoleninen, XXXIX. Reaktionen von 2‐Alkyl‐4,5,6,7‐Rn‐2H‐isoindolen (Rn=tetramethyl, tetrachlor) mit aktivierten C=C‐Dienophilen
Authors: Kreher Richard P. , Sewarte‐Roß G. , Vogt G.
Published: July 2007

Studies on the Chemistry of Isoindoles and Isoindolenines, XXXIX. — Reactions of 2‐Alkyl‐4,5,6,7‐Rn‐2H‐isoindoles (Rn=tetramethyl, tetrachloro) with Activated C=C Dienophiles

Substituted 2H‐Isoindoles 2 react with maleic imides in absolute ether. Cycloaddition in 1,3‐position leads to the formation of 1:1 adducts. The ratio between endo isomers 4 and exo isomers 5 depends on the substituents and the solvents. In the case of steric hindrance the Diels‐Alder addition can be induced by Lewis acids. In the presence of oxygen‐substituted 4,5,6,7‐tetrachloro‐2‐methylisoindolin‐1‐ones 7 are formed as minor products.
Synthese von 1,2‐Dioxolanen durch Ozonolyse 1,1‐disubstituierter nichtaktivierter Olefine
Authors: Reiser Ralf , Seeboth Rolf‐Günter , Sütting Carsten , Wagner Gabriele , Wang Jinkai , Schröder Gerhard
Published: July 2007

Synthesis of 1,2‐Dioxolanes by Ozonolysis of 1,1‐Disubstituted Nonactivated Olefins

Ozonolyses of the cyclopropyl‐substituted olefins 2a, 2b, and 2c do not produce the carbonyl oxides 1a, 1b, and 1c but formaldehyde oxide (1d); 1d can be trapped by the starting olefin and provides the 1,2‐dioxolanes 6a, 6b, and 6c, respectively, in ca. 10% yield. Other dioxolanes and normal ozonides may be obtained by the addition of olefins or aldehydes to solutions of the primary ozonides of 2a and 2b.
Wasserstoffübertragungen, 19. Zur Katalyse von Wasserstoff‐Transfer und 1,5‐H‐Shift durch Rhodium(III)‐chlorid in homogener organischer Phase
Authors: Wehage Hubert , Heesing Albert
Published: July 2007

Hydrogen Transfer Reactions, 19. — The Catalysis of Hydrogen Transfer and 1,5‐H Shift by Rhodium(III) Chloride in Homogeneous Organic Systems

In homogeneous solution, partly in the presence of a phase‐transfer catalyst, rhodium(III) chloride catalyzes the disproportionation of 1,3‐cyclohexadiene and to a lesser extent 1,5‐H shifts. In the start phase the catalyst is reduced to the active monovalent state. In these catalytic systems the dehydrogenation proceeds stereoselectively. – This was shown by tracer experiments and isotopes effects using deuterated 1,3‐cyclohexadienes 1a—d, which were synthesized with high isotopomeric purity.
Phosphinalkylene, 50. Zur Struktur von 2,2,2‐Triphenyl‐1,2λ5‐oxaphospholanen
Authors: Bestmann Hans Jürgen , Riemer Claus , Dötzer Reinhard
Published: July 2007

Phosphine Alkylenes, 50. — On the Structure of 2,2,2‐Triphenyl‐1,2λ5‐oxaphospholanes

2,2,2‐Triphenyl‐1,2Δ5‐oxaphospholanes (5a—h) were synthesized from methylene‐triphenylphosphorane (1, R=H) and suitable epoxides (2a—g). Oxaphospholane 5e was subjected to an X‐ray structural analysis, which showed a five‐membered ring‐structure with a trigonal‐bipyramidal coordinate phosphorus atom. One phenyl group and the ring oxygen atom are apical ligands at phosphorus. According to the NMR spectra, oxaphospholanes have a ring structure in nonpolar solvents, whereas in polar solvents there exists an equilibrium with an open‐chain form.
[3.3]Metacyclophane mit anti‐Konformation
Authors: Breitenbach Jörg , Hoss Ralf , Nieger Martin , Rissanen Kari , Vögtle Fritz
Published: July 2007

[3.3]Metacyclophanes with anti Conformation

The [3.3]metacyclophanes 5 and 9 with prevailing anti conformation were prepared by using different cyclisation techniques. 1H‐NMR studies and X‐ray structure analyses of both phanes 5 and 9 prove their unprecedented conformations.
Cyclische C6S6‐Isomere — Matrixspektroskopische und theoretische Untersuchungen
Authors: Maier Günther , Schrot Jürgen , Reisenauer Hans Peter , Frenking Gernot , Jonas Volker
Published: July 2007

Cyclic C6S6 Isomers — Matrix‐Spectroscopic and Theoretical Investigations

A yellow C6S6 isomer, which can be interconverted photo‐chemically into a colorless second C6S6 isomer, may be obtained upon matrix photolysis and flash pyrolysis of the precursor molecule 7. The structures of these isomers are most likely 3 and 5, as shown by comparison of their experimental with the calculated infrared spectra of the five possible cyclic C6S6 isomers 1—5.
Bis(di‐tert‐butylphosphanyl)methan‐Komplexe des Rhodiums: Geometrie, Elektronenstruktur und Derivate des 14‐Elektronenteilchens [Rh(dtbpm)Cl]. Molekülstruktur von Rh(dtbpm)Cl(PMe3)
Authors: Hofmann Peter , Meier Claudia , Englert Ulli , Schmidt Martin U.
Published: July 2007

Bis(di‐tert‐butylphosphanyl)methane Complexes of Rhodium: Geometry, Electronic Structure, and Derivatives of the 14‐Electron Fragment [Rh(dtbpm)Cl]. Molecular Structure of Rh(dtbpm)Cl(PMe3)

14‐Electron fragments [M(PR3)2X] (M = Rh, Ir, X = halogen etc.) are considered to be an important class of highly reactive, coordinatively unsaturated intermediates in many metal‐induced stoichiometric or catalytic transformations of organic substrates. As available theoretical data suggest a slightly preferred T‐shaped groundstate geometry with a less symmetric cis rather than the usually implied trans phosphane arrangement for such tricoordinate d8‐ML3‐type systems with monodentate phosphanes PR3, the chemistry of η2‐diphosphanylmethane complexes of rhodium with four‐membered RhPCP‐chelate rings and thus with enforced cis phosphane coordination and anomalously small cis P—Rh—P angles has been studied by theory and by experiment. MO calculations (EH) have been performed both for the model 14‐electron system [Rh(dhpm)Cl] (dhpm = diphosphanylmethane, H2P—CH2—PH2) and for the experimentally accessible fragment [Rh(dhbpm)Cl], where dtbpm is bis(di‐tert‐butylphosphanyl)‐methane, (tBu)2P—CH2—P(tBu)2. The electronic and geometric structure of these species is described. Employing the unusual ligand dtbpm, tailor‐made for stabilizing mononuclear η2‐ and destabilizing dinuclear μ‐diphosphanylmethane coordination, the chloro‐bridged dimer [Rh(dtbpm)Cl]2, has been synthesized. In agreement with steric and electronic considerations, its chemistry is dominated by a facile dissociation to monomeric (presumably solvent coordinated) fragments [Rh(dtbpm)Cl], even in benzene, as suggested by molecular mass determinations. Accordingly, by using [Rh(dtbpm)Cl]2 as a starting material, a series of sterically very congested but nevertheless mononuclear, square‐planar complexes Rh(dtbpm)Cl(L) (L = CO, PMe3, PPh3, PCy3, pyridine, acrylonitrile) with chelating dtbpm could be readily prepared and fully characterized. The relative stability of these potential alternative precursors of a [Rh(dtbpm)Cl] intermediate towards dissociation of ligands L is reported. The molecular structure of Rh(dtbpm)Cl(PMe3) as the first representative of this class of compounds has been determined by X‐ray crystallography.
Photoreaktion von (μ‐η]2:2‐Acetylen)tetracarbonylbis(η5‐cyclopentadienyl)‐dimolybdän und ‐wolfram mit Acetylen und 1,3‐Butadien
Authors: Kreiter Cornelius G. , Würtz Alban , Bell Peter
Published: July 2007

Photoreaktion von (μ‐η]2:2‐Acetylen)tetracarbonylbis(η5‐cyclopentadienyl)‐dimolybdenum and ‐tungsten with Acetylene and 1,3‐Butadiene

[Mo2(η5‐C5H5)2(CO)4(μ‐η2:2‐C2H2)] (1) and [W2(η5‐C5H5)2(CO)4‐(μ‐η2:2‐C2H2)] (2) react upon UV irradiation with acetylene, 1,3‐butadiene, and isoprene. Main products of the reactions with acetylene are the fly‐over complexes [M2(η5‐C5H5)2(CO)2(η1:3:3:1‐1,3,5‐hexatriene‐1,6‐diyl)] (8: M = Mo; 9: M = W). There is some IR evidence for the formation of [Mo2(η5‐C5H5)2(CO)(η5η1:4:1‐1,3‐butadiene‐1,4‐diyl)] (10). In addition [Mo3(η5‐C5H5)6(μ‐η1:2‐ethynyl)] (12) is obtained. 1 reacts with 1,3‐butadiene with C—C bond formation to give [Mo2(η5‐C5H5)2>(CO)(μ‐η1:2‐CO)(μ‐η1:2:3‐1,5‐hexadiene‐1,4‐diyl)] (15) and [Mo2(η5‐C5H5)2 (CO)4[μ‐η1:3‐E,Z‐2,4‐hexadiene‐1‐ylidene)] (18). With isoprene [Mo2(η5‐C5H5)2(CO)4[μ‐η1:3‐E,Z‐5‐methyl‐2,4‐hexadiene‐1‐ylidene)] (18a) is obtained. The reaction of 2 with 1,3‐butadiene yields six complexes. Beside thermolabile [W2 [W2(η5‐C5H5)2(CO) (μ‐η1:2:1‐3‐oxo‐1‐propene‐1, 3‐diyl)(η4‐1,3‐butadiene)] (21), (η5‐C5H5)2(CO) (μ‐η1:4‐3‐methylene‐1,4‐pentadiene‐1‐yl)] (20), the tungsten homologue of 15, [W2(η5‐C5H5)2(CO) (μ‐η1:2:3‐1,5‐hexadiene‐1,4‐diyl)] (16), its isomer [W2(η5‐C5H5)2(CO)2(μ‐η1:2:3‐1,5‐hexadiene‐1,4‐diyl)] (23) with a W—W double bond, and [W2(η5‐C5H5)2(CO)2(μ‐η1:2:1‐1,4‐hexadiene‐1,6‐diyl)] (17) are isolated. Furthermore, [W2(η5‐C5H5)2(CO)2 (μ‐η1:2‐vinylidene)] (11) is obtained. In solution 21 rearranges to 23. The crystal and molecular structures were determined for 15 and 18. The constitutions of the other products were deduced from the IR and 1H‐NMR spectra.
A Contribution to the Direct Observation of a Didehydroheteroaromatic with a Five‐Membered Ring: 2,3‐Didehydrothiophene
Authors: Teles Joaquim Henrique , Hess B. Andes , Schaad Lawrence J.
Published: July 2007

The flash vacuum pyrolysis and the photolysis of 2,3‐thiophenedicarboxylic acid anhydride (6) were investigated by using the technique of matrix isolation combined with FT‐IR spectroscopy. No conclusive proof for the existence of 2,3‐didehydrothiophene (1) could be found, but two hitherto unknown isomers were isolated and characterized: vinylidenethioketene (10) and thioformylvinylidenecarbene (15).
Ein Dipyrrino‐Cryptand — Synthese, Kristallstruktur, Metallkomplexierung
Authors: Seel Christian , Vögtle Fritz , Nieger Martin
Published: July 2007

A Dipyrrino Cryptand — Synthesis, Crystal Structure, Metal Complexation

The orange red cryptand 1, containing a dipyrrin chromophore, has been synthesized in seven steps. Its C2‐symmetrical X‐ray structure exhibits a planar dipyrrin unit and a twisted but not collapsed crown ring, two of the ether oxygen atoms projecting outwards. The complexation of alkali and transition metal cations by this concave dyestuff leads to changes of the color and to strong shifts in the UV/Vis spectra.
Synthese und Deoxygenierung substituierter 1‐Azaadamantan‐4,6‐dione
Authors: Risch Nikolaus , Billerbeck Ulrich , Krieger Evelyn
Published: July 2007

Synthesis and Deoxygenation of Substituted 1‐Azaadamantane‐4,6‐diones

1‐Azaadamantanes 5 and a variety of derivatives are accessible by a triple Mannich reaction of 1,3‐cyclohexanediones 1 with hexamethylenetetramine to yield the 1‐azaadamantane‐4,6‐diones 2. Deoxygenation of the sterically hindered and non‐enolizable β‐dioxo group in 2 succeeds by radical processes. Treatment with NaBH4/MeOH and subsequent chlorination give the dichlorides 4, which are dehalogenated with nBu3SnH. Quaternary ammonium salts 6 are available in high yields.
A General Synthesis of (Z)‐1,2‐Ethenediol Derivatives
Authors: Wulff Günter , Birnbrich Paul
Published: July 2007

By retro‐Diels‐Alder reaction of suitably substituted 9,10‐dihydro‐9,10‐ethanoanthracene‐cis‐11,12‐diol derivatives (4, 6, 8, 10, 12, 14) a number of known and unknown (Z)‐1,2‐disubstituted ethenes (5, 7, 9, 11, 13, 14) have been prepared in high yield, including derivatives with two different substituents. In contrast to this, attempts to prepare 1,3,2‐dioxasiloles bearing only substituents on the silicon atom gave dimers containing the ten‐membered ring system (Z,Z)2,2,7,7‐tetraalkyl‐1,3,6,8‐tetraoxa‐2,7‐disilacyclodeca‐4,9‐diene (19b, 21b, 23b, 25b). Again these compounds are formed diastereoselectively with respect to the double bonds.
Darstellung phenylsubstituierter Derivate des Tricyclo[4.1.0.02,7]heptans und des 1,2,3,4‐Tetrahydro‐1,2,3‐methenonapthalins
Authors: Stangl Roland , Jelinek‐Fink Hans , Christl Manfred
Published: July 2007

Preparation of Phenyl‐Substituted Derivatives of Tricyclo[4.1.0.02,7]heptane and 1,2,3,4‐Tetrahydro‐1,2,3‐methenonaphthalene

The phenyl derivatives 3, 4, and 13 of tricyclo[4.1.0.02,7]heptane (1) and 17, 20, and 22 of 1,2,3,4‐tetrahydro‐1,2,3‐methenonaphthalene (2) have been prepared from the dibromocarbene adducts of 1‐phenyl‐1‐cyclohexene, 3‐phenyl‐1‐cyclohexene, 1,3‐diphenyl‐1‐cyclohexene, 1,2‐dihydro‐2‐phenylnaphthalene, 1,2‐dihydro‐4‐phenylnaphthalene, and 1,2‐dihydro‐2,3‐diphenylnaphthalene, respectively, by treatment with methyllithium. The dibromocarbene adduct 10 of 1,6‐diphenyl‐1‐cyclohexene reacts with methyllithium to give the bicyclo[3.2.0.02,7]heptane 11.
Regioselective Acylations of Ketones to 1,3‐Diketones via Metalated Dimethylhydrazones[1]
Authors: Enders Dieter , Pathak Vijai N. , Weuster Peter
Published: July 2007

Acyclic and cyclic unsymmetrical ketones 1 are regioselectively acylated via their corresponding metalated dimethyl‐hydrazones 3 by using acid chlorides or anhydrides, arylnitriles, ethyl formate, carbon disulfide/methyl iodide, alkyl chloroformates, dialkyl carbonates, phenyl isocyanate, or phenyl isothiocyanate as acylating agents. Subsequent acidic hydrolysis leads to the 1,3‐diketones 6 in acceptable to excellent overall yields. The tautomeric structure of the product hydrazones 4, 5, 7, and 8 is determined. Cyanation of 3 with cyanogen bromide affords the α‐cyano dimethylhydrazones 9.