bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Specific Route to Enantiomerically Pure Asymmetric (η6‐Arene)(η4‐1,5‐cyclooctadiene)Ru(0) Complexes
Authors: Heinemann Frank , Klodwig Ens , Knoch Falk , Wündisch Marion , Zenneck Ulrich 
Published: July 2007

AbstractChiral or achiral (arene)(COD)Ru complexes can be made by replacing the η6‐ligands of (η4‐1,5‐COD)(η6‐1,3,5‐cyclooctatriene)Ru (1) or (η4‐1,5‐COD)(η6‐naphthalene)Ru (2) by a suitable arene. This well known reaction has been extended to mono‐ and dibromoarenes and we report a novel route to substituted (arene)(COD)Ru species, utilizing (bromoarene)‐(COD)Ru as starting materials. These facilitate a rapid bromine‐lithium exchange reaction with nBuLi at low temperatures and the lithiated species react readily with alkyl chloroformates as electrophiles. By using chiral electrophiles [alkyl = (‐)‐menthyl] enantiomerically pure or diastereomeric complexes containing CO2R* groups are formed, depending on the symmetry of the original complex. A diastereomeric 1:1 mixture was separated by recrystallization. All (arene)‐(COD)Ru complexes tested so far are useful as catalysts for the hydrogenation of simple alkenes at room temperature.
Multiple Bonds between Main‐Group Elements and Transition Metals, CLXV. Rhenium(V) Oxo Complexes with Bidentate Schiff Bases: Structures and Catalytic Applications
Authors: Kühn Fritz E. , Rauch Monika U. , Lobmaier Gerhard M. , Artus Georg R. J. , Herrmann Wolfgang A. 
Published: July 2007

AbstractReaction of [NBu4][ReOCl4] (1) with bidentate salicylidene amine ligands (salen = HL) (2a‐c) leads to the formation of monomeric octahedral rhenium (V) compounds of formula [ReOCl (L)2] (3a‐c). Spectroscopic date indicate asymmetric arrangement of the ligands in the complexes. This is confirmed by the X‐ray crystal structures of 3b and 3c. Complexes 3a, b have been tested as catalysts for the epoxidation of cyclooctene. No evidence for decomposition for decomposition of the catalysts is observed during the reaction (as in the case for tri‐and tetra‐dentate salen complexes). No undesired byproducts are formed in the catalytic reactions.
Hydrocarbon‐Bridged Complexes, XL. Polyene‐Bridged Iridium(III), Palladium(II), and Platinum(II) Complexes of Schiff Bases from α,ω‐Polyene Dialdehydes and α‐Amino Acids or o‐Aminophenol
Authors: Fehn Armin , Briel Oliver , Beck Wolfgang 
Published: July 2007

AbstractSchiff bases 111 were synthesized from α‐amino acids or o‐aminophenol and crocetindialdehyde, 2,7‐dimethyloctatrienedial, terephthalaldehyde, or β,β′ ‐p‐phenylendiacroleine. The reactions of these Schiff bases with chloro‐bridged complexes [(R3P)(Cl)M(η‐Cl)]2 (M = Pd, Pt) and [(C5Me5)(Cl)Ir(°Cl)]2 gave the dinuclear complexes 12–31.
New Phosphorus Heterocycles by Rearrangement of a [1,4‐Bis(trimethylsilyl) η8‐cyclooctatetraene‐1,3,5‐triphospha‐7‐hafnanorbornadiene Complex
Authors: Binger Paul , Leininger Stefan , Günther Klaus , Bergsträßer Uwe 
Published: July 2007

Abstract[1,4‐Bis(trimethylsilyl)‐n8‐cyclooctatetraene]‐2, 4, 6‐tri‐tert‐butyl‐1, 3, 5‐triphospha‐7‐hafnanorbornadiene (3) rearranges nearly quantitatively to the corresponding 3,5,6‐tri‐tert‐butyl‐1,2,4‐triphospha‐7‐hafnanorbornadiene complex 5 upon heating at 70°C. Treatment of complex 5 with trimethylphosphane at 50°C induces the displacement of di‐tert‐butylacetylene to give the new (n4‐triphosphacyclobutadiene)hafnium complex 7, the crystalstructure of which has been determined by X‐ray analysis. From complex 5 3,5,6,‐tri‐tert‐butyl‐1,2,4‐triphospha Dewar benzene (6) can be synthesized by a redox reaction with hexachloroethane.
Synthesis and Characterization of Substituted Benzyl Zinc Derivatives ‐ Molecular Structures of (tmeda) Li‐CH (GeMe3)Ph, (tmeda)Zn(CH2Ph)2, (tmeda)Zn[CH(SiMe3)Ph]2, and (tmeda)Zn[CH(SiMe3)Ph]N(H)Si(SiMe3)3
Authors: Westerhausen Matthias , Wieneke Michael , Rademacher Bernd B. , Schwarz Wolfgang 
Published: July 2007

AbstractThe reaction of lithium phenyl(trimethylsilyl)methanide with phenyl(trimethylsilyl)methylzinc chloride‐tmeda in the presence of tmeda yields the addition product, a bis(tmeda)‐lithium dialkylchlorozincate. The elimination of lithium chloride leads to the formation of a tmeda adduct of bis[phenyl‐(trimethylsilyl)methyl]zinc. The metathesis reaction of phenyl(trimethylsilyl)methylzinc chloride‐tmeda with lithium tris(trimethylsilyl)silylamide allows the isolation of the corresponding heteroleptic tmeda complex of an alkylzinc amide. The metalation of phenyl(trimethylstannyl)methane with butyllithium yields the transmetalation product benzyllithium. From the metathesis reaction of this lithium base with anhydrous zinc(II) chloride in the presence of tmeda, the tmeda adduct of dibenzylzinc crystallizes. The molecular structures of (tmeda)LiCH(GeMe3)Ph, (tmeda)Zn(CH2Ph)2, (tmeda)Zn[CH(SiMe3)Ph]2, and (tmeda)Zn[CH(SiMe3)‐Ph[N(H)Si(SiMe3)3 are reported. Whereas lithium bonds in an η3‐fashion, the zinc atom forms a σ(ZnC) bond. The extremely wide ZnNSi angle in (tmeda)Zn[CH(SiMe3)‐Ph[N(H)Si(SiMe3)3 of 157° is remarkable.
Dirhenium Complexes with S2CPR3 Bridges Donating Four and Eight Electrons — X‐ray Structures of [Re2(CO)8{μ‐η1;η1‐S2CPCy3}] and {Re2(CO)6{μ‐η3;‐S2CPCy3}] and [Re2(CO)6{μ‐η2; η3‐S2CPCy3}]
Authors: Alvarez Bernardo , Li Jing , Miguel Daniel , Morales M. Dolores , Riera Victor , García‐Granda Santiago 
Published: July 2007

AbstractThe reaction of fac‐[Re(CO)3(S2CPR3)Br] with [Rc(CO)5]− affords the dinuclear octacarbonyl compounds [Re2(CO)8(μ‐S2CPR3)] (3ab), which have been isolated and characterized by spectroscopic methods. An X‐ray crystal‐structure determination of the derivative 3a (RCy) shows that the S2CPCY3 ligand acts as an η1(S);η1(S′) bridge donating two electrons to each metal atom of a symmetrical (CO)4ReRe(CO)4 unit. This unit is presumably formed through a concerted process involving carbonyl/sulfur exchange in the nonsymmetrical octacarbonyl (CO)3(S2CPR3)ReRe(CO)5 generated after the coupling of the bromo derivative with the carbonyl anion. Complexes 3ab can be obtained more directly by adding S2CPR3 to [Re2(CO)8(μ‐H)(μ‐CHCHnBu)], which is formed by irradiation of Re2(CO)10 with 1‐hexene. Hydride addition to the central carbon atom of the S2CPR3 ligand of 3a–b occurs with loss of PR3, to give the anion [Re2(CO)8(μ‐S2CH)]− which may be isolated as a salt with the PPN+ cation. The octacarbonyl compounds 3a–b can be converted into hexacarbonyl complexes [Re2(CO)6(μ‐S2CPR3)] (5a–b) by heating in toluene or octane at reflux temperature. According to an X‐ray crystal‐structure determination of the derivative 5a (RCy), the loss of one carbonyl ligand from each rhenium atom is accompanied by the rearrangement of the S2CPR3 ligand which changes its bonding mode from η1(S);η1(S′) donating four electrons to η3(S,C,S′);η2(S,S′) donating eight electrons.
Synthesis of Novel Optically Active Tin Hydrides Containing Chiral Ligands
Authors: Schwarzkopf Kay , Metzger Jürgen O. , Saak Wolfgang , Pohl Siegfried 
Published: July 2007

AbstractThe synthesis of the chiral tin bromides 1‐4 and hydrides 5‐8, containing the potentially bidentate, optically active 2‐[ (1 S/R)‐ 1 ‐dimethylaminoethyl]phenyl and 2 ‐[( 1 S) ‐ 1 ‐dimethylamino‐2,2‐dimethylpropyl]phenyl ligands, is reported. The tin hydrides 5‐8, with the tin atom as the stereogenic centre, were isolated as diastereomeric mixtures with diastereomeric ratios of dr = 50:50 up to dr = 80:20. The absolute configuration of (—) ‐ (1 S)‐ 1 ‐ (2‐bromophenyl) ‐2,2‐dimethylpropylamine [(S)‐10] was determined by single‐crystal X‐ray structure analysis.
Cobalt Phthalocyanine Derivatives Supported on TiO2 by Sol‐Gel Processing. Part 1: Preparation and Microstructure
Authors: Schubert Ulrich , Lornez Anne , Kundo Nicolay , Stuchinskaya Tatiana , Gogina Ludmila , Salanov Alexel , Zalkovskii Vladimir , Maizlish Vladmir , Shaposhmikov Gennadii P. 
Published: July 2007

AbstractCobalt(II) 2,9,16,23‐tetrasulphophthalocyanine and cobalt(II) 2,9,16,23‐tetra(chlorosulphonyl)phthalocyanine were supported on TiO2 by reaction of the phthalocyanines with Ti(OR)4 followed by sol‐gel synthesis. The thus obtained solid materials are stable in sulfide‐containing media and are therefore suitable as catalysts for HS oxidation. The structure of the samples was characterized by electron microscopy diffraction. The morphology of the matrix strongly depends on the cobalt phthalocyanine derivative. The pathalocyanines in the titania matrices are monomeric or dimeric depending both on the type of substituents of the CoPc derivative and on the titanium alkoxide used as precursors.
Dichlorogermylene‐Alkyldichlorophosphane Reactions Revisited: Characterisation of Bis(trichlorogermyl)phosphanes, Trichlorogermyldiphosphanes, and Ge‐P Heterocycles
Authors: Karnop Michael , Mont Wolf‐Walther Du , Jones Peter G. , Jeske Jörg 
Published: July 2007

AbstractThe reactions of alkyldichlorophosphanes 1 (RPCl2; R = tert‐butyl: 1a, R = isopropyl; 1b, R = 1‐adamantyl: 1c) with the germanium dichloride dioxane complex were followed by 31P NMR. Depending on the organic substituents and the reaction conditions, mixtures of trichlorogermylphosphanes RP(GeCl3)2 4a‐c, RPHGeCl3 5a‐c, diphosphanes R(H)PP(H)GeCl3 6a‐c, R(Cl)PP(H)GeCl3 7a, b cyclophosphanes, and Ge‐P heterocycles such as triphosphadigermolanes (RP)3(GeCl2)2 8a, b and tetraphosphagermolane (RP)4)GeCl2 10b are formed. As a further unexpected byproduct of the reaction of 1a with GeCl2–dioxane, a small amount of tri‐tert‐butyl(trichlorogermyl)cyclotetraphosphane 9a was isolated. From the reaction of 1c with two equivalents of GeCl2–dioxane, separation from byproducts 5c and 6c by crystallisation furnished colourless crystals of 4c (R = 1‐adamantyl) as the first pure organylbis(trichlorogermyl)phosphane. Surprisingly, the reaction of isoprophylphosphane with germanium tetrachloride, intended to prepare 5a, led to crystalline isopropylphosphonium trichlorogermanate(II) 11. The structures of molecular 4c and 9a and ionic 11 were determined by X‐ray crystallography.
Coordination Chemistry of Functional Phosphanes, VI. Rhodium and Iridium Complexes with 2‐(Diphenylphosphophanyl)phenylamido Ligands
Authors: Dahlenburg Lutz , Herbst Kourad 
Published: July 2007

AbstractTreatment of trans‐[MCl(CO)(PPH3)2] (M = Rh, Ir) with the lithium salts fof the bidentate hybride ligands 2‐Ph2PC6H4N(R)H [‘PN(R)H’ R = H, Me] produced the chelate complexes [M(CO)(PPH3)(‘PNR’)] [M/NR = Rh/NH (1a), Ir/ NH (2a), Rh/NMe (1b), Ir/NMe (2b)] containing the CO ligand and the NR substituent in mutual trans‐arrangement. 2b was shown by single‐crystal X‐ray diffraction to possess an amido‐nitrogen atom in a trigonal‐planar environment. Oxidative addition of H2 to 2b reversibly formed cis‐[IrH2(CO)(PPh3)(‘PNMe’)] (3), in which H2 has added perpendicular to the N–Ir–CO axis. While both 1a,b and 2a, b proved to the completely unreactive toward CO2 at ambient temperature and pressure, reactions of 1a and 2a/b with sulfur dioxide reversibly formed pentacoordinate SO2 adducts, [M(SO2)(CO(PPh3)(‘PNR’)][M/NR = Rh/Nh (4a), Ir/NH (5a), Ir/NMe (5b) with M–S‐bonded pyramidal MSO2 units as established by an X‐ray structure analysis of 5a. Complex 5b reacted with dioxygen to form the sulfato compound [Ir(O2SO2)(CO)(‘PNMe’)] (6). Combination of 2a with HCl in CHCl3 at −60°C resulted in protonation of both the iridium and the nitrogen atom to give an ionic chelate complex, [IrHCl(CO)(PPh3)(‘PNH2’)]Cl (7), containing one of its NH groups hydrogen‐bonded to Ir–Cl. Ring opening of the chelate structure with formation of [IrHCl2(CO)(PPh3)(PPh2C6H4N(Me)H‐o)] (8) was observed in the analogous reaction of 2b with hydrogen chloride. NMR spectroscopy showed 8 to exist in CDCl3 solution as a mixture of three Ir–PPh2C6H4N(Me)H‐o rotamers, stabilized by intramolecular –N(Me)H —ClIr hydrogen bonding.
Tetra(amino)methanes: Implications of Their Structure and Reactivity Pattern for Hypothetical Carbon Nitride Frameworks
Authors: Jockisch Alexander , Schier Annette , Schmidbaur Hubert 
Published: July 2007

AbstractBecause of their possible role as model compounds for the structural units of carbon nitride C3N4, the preparation, structural chemistry, and some representative reactions of tetra(amino)methanes have been (re)investigated. In the crystal, C(NMe2)4 (1) has a molecular geometry close to D2a symmetry as proposed by theoretical calculations using state‐of‐the‐art density functional methods. The coordination of the central carbon atom is distorted tetrahedral and the configuration of the nitrogen atoms is strongly pyramidal, as opposed to almost planar in the tetra(amino)silanes. Tetra(pyrrolidinyl)methane has a similar core structure, with all heterocyclic substituents in an envelop conformation flexible in solution. Tetra(piperidinyl)methane is more rigid in solution, owing to a more congested structure, with much higher inversion barriers for the six‐membered rings. Hydrolysis of 1 leads to MezNH and hexamethylguanidinium hydroxide, and treatment of 1 with HAuCl4(aq) affords crystalline [C(NMe2)3]4 AuCl4− the structure of which has also been determined. Compound 1 is a strong nucleophile and can be used as an aminating agent, converting e.g. halosilanes into dimethylaminosilanes, with the guanidinium cation as the leaving group. The experimental results are discussed in the light of recent predictions regarding bulk carbon nitrides.
Density Functional Studies on Amino‐Substituted Methane and Silane
Authors: Albert Katrin , Rösch Notker 
Published: July 2007

AbstractIn all‐electron density functional calculations on mono‐ and tetraaminosubstituted methane and silane the coordination around the nitrogen center is found, in complete agreement with experiment, to be less pyramidal in the silicon compounds. The calculated barrier to inversion at nitrogen is only 0.6 kcal/mol in silylamine, while in methylamine it is 5.5 kcal/mol. The larger flexibility is attributed to the greater ionic character of the Si‐N bond compared to that of the C‐N bond. In tetra(amino)methane, inversion of one amino group leads to a local minimum (calculated inversion barrier: 6.4 kcal/mol), while a corresponding structure (or barrier) does not exist for the silicon compound. Due to the steric influence of the amino groups, the barrier to rotation around the C‐N bond is larger in the tetrasubstituted compound (6.4 kcal/mol compared to 2.3 kcal/mol in methylamine). While the average binding energy of the amino groups is similar in both tetra(amino)compounds, the binding energy of the fourth ligand is about 25% larger in the silicon compound for both homolytic and heterolytic bond cleavage. This difference arises from the relative stabilization of the tri(amino)‐methyl species, due to some n contribution to the C‐N bond.
Synthesis of the Diazadisilatitanacyclopentane RSi(NH2)NHTiMe(cp*)NHSi(NH2)R (R =PhNSiMe3, cp *=η5‐C5Me5
Authors: Böttcher Peter , Wraage Karsten , Roesky Herbert W. , Lanfranchi Maurizio , Tiripicchio Antonio 
Published: July 2007

AbstractReaction of two equivalents of N‐trimethylsilylaniline (1) with two equivalents of n‐butyllithium, followed by subsequent treatment with Si2Cl6 (2) leads to the formation of the tetrachlorodisilane RSiCl2SiCl2R (3) (R = PhNSiMe3). 3 is converted to RSi(NH2)2Si(NH2)2R (4) by reaction with liquid ammonia. 4 reacts with cp*TiMe3 (5) (cp* = η5‐CsMe5) to yield the diazadisilatitanacyclopentane RSi(NH2)NHTiMe(cp*)NHSi(NH2)R (6). The crystal structure of 6 is reported.
N′,N′,N″,N″‐Tetramethylguanidine‐Substituted Phosphoryl Compounds as Ligands in Transition Metal Chemistry – Unusual Modes of Coordination
Authors: Münchenberg Jochen , Thönnessen Holger , Jones Peter G. , Schmutzler Reinhard 
Published: July 2007

AbstractMethyl‐ and tert‐butylphosphonic bis(N′,N′,N″,N″‐tetramethylguanidinide) 1 and 2 were allowed to react with various transition metal compounds. The resulting complexes were studied by IR spectroscopy, mass spectrometry and, in the case of 10, by NMR spectroscopy. In the case of the compounds 7–10 the metal was coordinated only via the imino nitrogen atoms of 2, (IR evidence). X‐ray structure analyses were performed for [L1CoBr2]2 6, L2CuCl2 9, and L2PdCl2 10 (L1 = 1, L2 = 2). In 5 L1 acts as an N,O bridging ligand, leading to tetrahedral coordination at Co and eightmembered (‐Co‐O‐P‐N‐)2 rings. In 6 coordination by L2 chelates the metal atom through two N atoms, leading to PN2M rings; the coordination geometry is distorted planar.
Synthesis and Characterization of Novel Octakis(2′‐aminophenoxy and 2′‐Aminophenylsulfanyl)‐Substituted Metallophthalocyanines
Authors: Kandaz Mehmet , Bekaro.Lu özer 
Published: July 2007

AbstractNovel phthalocyanines (M = Ni, Zn, Co) bearing eight 2′‐aminophenoxy and 2′‐amino phenylsulfanyl substitutents on peripheral positions have been prepared starting from 4,5‐bis(2′‐aminophnoxy)−1,2‐dicyanobenzene and the corresponding anhydrous metal salts [NiCl2, Zn(O2CMe)2, CoCl2]‐ Complexation of octakis(2′‐amino phenylsulfanyl)‐substituted metallo phthalocyanines (2b, 3b and 4b) with Pd11 to form the pentanuclear product was accomplished from their mixtures.
Mass Transfer Coefficients in Mechanically Agitated Gas‐Liquid Contactors
Authors: Markopoulos J. , Christofi C. , Katsinaris I. 
Published: July 2007

AbstractThere are a large number of correlations given in literature for the prediction of volume‐related liquid‐side mass transfer coefficients in mechanically agitated gas‐liquid contactors. Significant disagreement can be observed concerning the proposed correlations, so that no single correlation exists representing all of the mass transfer data given in the literature. The observed differences can mainly be ascribed to the differences in the geometry of the system, the range of operational conditions and the measurement method used. On the basis of a comparative study of mass transfer phenomena in agitated Newtonian and non‐Newtonian aerated liquids, a critical discussion of the literature results is presented in this review article, so that final conclusions can be drawn for the kLα values in the different single‐ and multiple‐impeller agitated systems studied in the literature.
Enzymatic Hydrolysis of Corn Stover after Pretreatment with Dilute Sulfuric Acid
Authors: Lu X. B. , Zhang Y. M. , Yang J. , Liang Y. 
Published: July 2007

AbstractAlthough many previous studies have been carried on the enzymatic hydrolysis of corn stover after pretreatment with dilute sulfuric acid, this paper emphasizes the use of different conditions to attain the highest yields of two sugars, xylose and glucose, from both stages. The pretreatment was performed at a range of sulfuric acid concentrations of 2, 4 and 6 % at 80, 100 and 120 °C. Up to 77 % xylose yield was obtained while the glucose yield was only 8.4 %. The corresponding solid phase was hydrolyzed by cellulase and the influences of five factors and their interactions on enzyme hydrolysis were evaluated by response surface methodology based on one‐factor‐at‐a‐time experiments. The optimal levels for each variable to obtain the highest reducing sugar yield were as follows: enzyme concentration of 22 FPU/g substrate, substrate concentration of 77 g/L, temperature of 49 °C, pH 4.8 and reaction time of 38 h. A reducing sugar yield of 42.11 g/100 g substrate was achieved, which was consistent with the predicted value of 42.13 g/100 g substrate. Compared with the one‐factor‐at‐a‐time experiments, there was a 9.4 % increase in reducing sugar yield when the enzyme concentration was decreased to 3 FPU/g substrate, the substrate concentration increased to 17 g/L and the reaction time dropped to 22 h. The total sugar released from the two stages was 62.81 g/100 g substrate.
Effect of CaSO4 Pelletization Conditions on a Novel Process for Converting SO2 to Elemental Sulfur by Reaction Cycles Involving CaSO4/CaS – Part II: Reduction of SO2 with CaS
Authors: Choi M. E. , Sohn H. Y. , Ahmed Y. M. Z. , Mohamed F. M. , Han G. , Shalabi M. E. H. 
Published: July 2007

AbstractA new process for converting sulfur dioxide to elemental sulfur by a cyclic process involving calcium sulfide and calcium sulfate without generating secondary pollutants, developed at the University of Utah, was described in Part I of this series. In this process, sulfur dioxide is reacted with calcium sulfide to produce elemental sulfur and calcium sulfate; the latter is reduced by hydrogen to regenerate calcium sulfide. Here, in Part II, the effects of different pelletization conditions for the initial reactant calcium sulfate on the reactivity of CaS pellets produced from calcium sulfate pellets toward sulfur dioxide were studied. Experiments were performed to investigate the effects of temperature in the range 1023–1173 K, pellet size, cycle repetition, and water vapor or carbon dioxide content in the sulfur dioxide stream. The binder amount and the presence of nickel catalyst did not significantly affect the reaction rate.
Process and Laboratory Scale UV Inactivation of Viruses and Bacteria Using an Innovative Coiled Tube Reactor
Authors: Schmidt S. , Kauling J. 
Published: July 2007

AbstractAvoidance and elimination of viral contamination in biotechnological and pharmaceutical processes is a crucial issue. The novel UVivatec coiled tube reactor was designed for UV irradiation of cloudy liquid media. It very effectively inactivates especially critical viruses and avoids high product losses. The method proposed is an ideal complement to existing and established processes.
Conversion of Biomass Based Slurry in an Entrained Flow Gasifier
Authors: Santo U. , Seifert H. , Kolb T. , Krebs L. , Kuhn D. , Wiemer H.‐J. , Pantouflas E. , Zarzalis N. 
Published: July 2007

AbstractA two‐step process, BIOLIQ, with pyrolysis and subsequent entrained flow gasification has been developed at the Forschungszentrum Karlsruhe to produce synfuel from biomass. Experiments in a 60 kW pilot‐scale atmospheric entrained flow gasifier allow quantitative evaluation of the combustion behavior of biomass‐based slurry, leading to a better understanding of the gasification process.
Extended Dötz‐Like Cyclization Reactions Towards the Synthesis of Eight‐Membered Ring‐Containing Polycycles: Scope and Theoretical Studies
Authors: Barluenga José , Fañanás‐Mastral Martín , Palomero M. Angel , Aznar Fernando , Valdés Carlos 
Published: July 2007

AbstractThe reaction between cyclobutene‐containing dienyl Fischer carbene complexes (FCCs) and alkynes has been studied from both an experimental and a theoretical point of view. We have found that the reaction follows different pathways depending on the nature of the terminal double bond of the carbene complex. Thus, eight‐membered carbocycles have been obtained from an extended Dötz‐like reaction of dienyl FCCs and indolyl‐ or benzofuryl‐substituted alkenyl FCCs. On the other hand, phenyl‐ and naphthyl‐substituted alkenyl FCCs follow a typical benzannulation pathway giving rise to cyclohexadienones. DFT calculations have allowed us to formulate detailed mechanistic proposals and to provide an explanation for the formation of either the benzannulation products or the eight‐membered carbocycles.