bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photochemical and Thermal Rearrangement of Acyl‐Substituted Quinone Methides, Accessible by Dimethyldioxirane Oxidation of Benzofurans and Subsequent Valence Isomerization of the Resulting Epoxides
Authors: Adam Waldemar , Sauter Markus 
Published: July 2007

AbstractThe photoisomerization of quinone methides 3 to benzocycloheptafuran 4 and the thermolysis of the latter to xanthenes 5 are reported. The quinone methides 3 are accessible by dimethyldioxirane oxidation and subsequent valence isomerization of the resulting benzofuran epoxides 2. On irradiation (λ > 400 nm), the quinone methides 3 rearrange by cyclization to the corresponding norcaradiene, and ring enlargement affords the benzocycloheptafurans 4. Thermolysis of the cycloheptatrienes 4 leads to the xanthenes 5, first by cycloreversion to the norcaradienes, followed by electrocyclization to the chromenes and tautomerization of the latter. The new cycloheptatrienes 4 and xanthenes 5 were fully characterized.
Zur Energiedelle des orthogonalen Trimethylenmethans. – 1‐Methylen‐2‐phenylcyclopropan‐Thermolyse
Authors: Roth Wolfgang R. , Winzer Markus , Lennartz Hans‐Werner , Boese Roland 
Published: July 2007

Energy Well of the Orthogonal Trimethylenemethane. – 1‐Methylene‐2‐phenylcyclopropane ThermolysisFrom the heat of hydrogenation of 5, the activation enthalpy for the racemization of the title compound, and the oxygen dependance of the trapping rate of the intermediate diradical 8 the energy profile for the degenerate methylene‐cyclopropane rearrangement can be constructed, which leads to heats of formation for the triplet and singlet state of the diradical 8 of ΔHf0 · 93.9 and 95.6 kcal mol–1, respectively.
Stereoselektive Synthese von 3‐substituierten Cyclobutanolen und Folgeprodukten
Authors: Dehmlow Eckehard V. , Büker Sabine 
Published: July 2007

Stereoselective Synthesis of 3‐Substituted Cyclobutanols and Products Derived Therefrom3‐Substituted cyclobutanones 2 are prepared by alkene/dichloroketene cycloadditions and subsequent dehalogenation. Reduction with LiAlH(OtBu)3 furnishes cis‐cyclobutanols 3 in 95–100% selectivity. Mitsunobu inversion turned out to be the only practical method to get trans isomers 4 in high selectivity. A stereoselective cyclobutanol→bromocyclobutane conversion could be achieved only by a modified Mitsunobu reaction. Cross coupling between zinc derivatives of bromocyclobutanes 9 and aromatic bromides is not stereoselective.
Anwendungen der Phasentransfer‐Katalyse, 61[1]. Notiz über die Steuerung von O‐/C‐Alkylierungen mit Hilfe von Phasentransfer‐Katalysatoren
Authors: Dehmlow Eckehard V. , Richter Rolf 
Published: July 2007

Applications of Phase Transfer Catalysis, 61[1]. – Directing Effects on O‐ vs. C‐Alkylations by Phase Transfer CatalystsStrong catalyst effects on the O‐ vs. C‐alkylation ratio of 1,1‐dimethylindan‐2‐one (4) by dimethyl sulfate are found. They differ in the two consecutive alkylation steps and range between <1 and ≈60. No such catalyst influence exists in the methylation of 2‐methylindane‐1,3‐dione (1).
Allenkomplexe des Titanocens und Zirkonocens: Darstellung und Reaktivität
Authors: Binger Paul , Langhauser Franz , Wedemann Petra , Gabor Barbara , Mynott Richard , Krüger Carl 
Published: July 2007

Allene Complexes of Titanocene and Zirconocene: Synthesis and ReactivityBis(trimethylphosphane)titanocene (1) and (η2‐Ethene)(trimethylphosphane)titanocene (2) react with one equivalent of allene (3a), phenylallene (3b), 1,1‐dimethylallene (3c), and 1,1‐diphenylallene (3d) readily by displacement of one trimethylphosphane from 1 and of ethene from 2 to give regiospecifically the corresponding (η2‐allene)(trimethylphosphane)‐titanocene complexes 4a–d in good yields. From (η2‐1‐butene)(trimethylphosphane)zirconocene (6) and 3d the corresponding (1,2‐η2‐3,3‐diphenylallene)zirconocene complex 7d is obtained in the same manner. The structures of these new allene complexes have been established unambiguously by 1H‐ and 13C‐NMR‐spectroscopy. A crystal structure analysis of the titanocene complex 4d confirms the spectroscopic structure determination. All the above mentioned allene‐metallocene complexes consume readily a second equivalent of the allene derivatives to produce, in most cases, regiospecifically the corresponding 1‐metalla‐2,5‐dimethylenecyclopentane derivatives 5a–d (M = Ti) and 8c, d (M = Zr); only the (allene)zirconocene complex 7a gives rise to a 1:1 mixture of the regioisomers 8a and 9. More conveniently 5a–d and 8c, d are synthesized directly from metallocene dichloride and the corresponding allenes 3.
Chlorotrioxorhenium. Neue Synthesen, Reaktionen und Derivate
Authors: Herrmann Wolfgang A. , Kühn Fritz E. , Romão Carlos C. , Kleine Matthias , Mink Janos 
Published: July 2007

Multiple Bonds between Main Group Elements and Transition Metals, CXXIX[1]. — Chlorotrioxorhenium. Novel Syntheses, Reactions, and DerivativesChlorotrioxorhenium (1a) and homologs of formula X‐ReO3 (1b–e) are generated from Re2O7 and either ZnX2, (n ‐ C4H9)3SnX, [(n‐C4H9)4N]X, or [(C6H5)4P]X in clean reactions. Compounds 1a–f form with stable six‐coordinate adducts XReO3 ·L (2a–f, 3a, 4a, 5a: L = N,N′‐ligand) upon addition of the free ligand L, e.g. 2,2′‐bipyridine. 1a is readily alkylated by means of SnR4 or ZnR2 to form organorhenium(VII) oxides in good yields. These synthetic routes have the advantage to proceed under very mild conditions. The adducts of 2,2′‐bipyridine with halorhenium(VII) oxides show characteristic thermogravimetric (TG) behavior that reflects the volatility of the uncoordinated complexes X‐ReO3.
Synthese und Charakterisierung von Gallium‐Phosphor‐Heterocubanen
Authors: Niediek Katharina , Neumüller Bernhard 
Published: July 2007

Synthesis and Characterization of Gallium‐Phosphorus HeterocubanesThe reaction of iPrGaCl2 with tBuPLi2 in Et2O at −78°C gives the heterocubane [iPrGaP(tBu)]4 (1) by using the “dilution principle”. {(MesGa)3[GaP(H)tBu][P(tBu)]4} (2) was formed, when three equivalents of MesGaCl2 and one equivalent of GaCl3 in THF at −78°C were treated with 5 equivalents of tBuPLi2. Compounds 1 and 2 were characterized by NMR, IR, and MS techniques as well as by X‐ray structure determination. The heterocubane molecules of 1 are disordered in the crystal; every atom site of the central cubical frame work is occupied by gallium and phosphorus atoms (occupation factor 0.5). The structure of 2 contains two crystallographically unique molecules, which are not disordered because of the additional P(H)tBu groups.
Ein neuer Zugang zum ikosaedrischen closo‐NB11‐Gerüst
Authors: Schneider Lenka , Englert Ulli , Paetzold Peter 
Published: July 2007

A Novel Access to the Icosahedral closo NB11 SkeletonAt 200°C, the open skeleton of NB9H12 is closed to the icosahedral skeleton of NB11H10Y (3) by the action of three equivalents of Et3N · BH3, whereby one equivalent forms a bridge Y = BH2NEt2CH2CH2 between the adjacent cluster atoms N1 and B2; the product 3 crystallizes in the space group P¯. With L · BH3 (L = NMe3, SMe2) instead of Et3N · BH3, the nido‐borane NB9H12 is transformed into the closo‐borane (LBH2)NB11H11 (4a, b) at 140°C. By allowing tBuNH2 to react with 4b, the N‐bonded ligand Me2SBH2 is removed with formation of the aza‐closo‐dodecaborate [t BuNH3] [NB11H11], thus opening a new route to closo‐NB11H12.
Zur Kenntnis der carbonylmethylenierenden Molybdän‐Aluminium‐ und Wolfram‐Aluminium‐μ‐methylen‐Komplexe
Authors: Kauffmann Thomas , Enk Manfred , Fiegenbaum Petra , Hansmersmann Ursula , Kaschube Wilfried , Papenberg Michael , Toliopoulos Euripides , Welke Siegfried 
Published: July 2007

Organomolybdenum and Organotungsten Reagents, VI[1]. On the Carbonyl‐Methylenating Molybdenum‐Aluminium and Tungsten‐Aluminium μ‐Methylene ComplexesMoCl5, MoOCl3(THF)2, MoO2Cl2, (MeO)2MoCl3, (MeO)4MoCl, WOCl3(THF)2, and WOCl4 form carbonyl‐methylenating complexes and 1–2 equiv. of CH4 by reacting with 2 equiv. of Me3Al. These thermolabile complexes are prepared in solution and differ in their properties (e.g. ability to transfer mostly more than 1 CH2 unit per Mo or W atom in carbonyl‐olefinating processes; high sensitivity to water, no hydroxy ketone affinity) from the carbonyl‐olefinating 1,3‐dimetallacyclobutanes (M = Mo, W) and are believed to be mono‐ and bicyclic analogs (e.g. hypothic structures 3, 6–8) of the Tebbe reagent (1), containing Mo‐μCH2 Al or W ‐μCH2 Al groups, respectively. Analogous complexes seem to be produced by treating MoOCl3(THF)2 with 2 Me2Zn or (MeO)2MoCl3 and (MeO)4MoCl with 2 MeMgBr in each case. Unlike the dimeric and, due to a MoMo bond, diamagnetic Mo derivatives (MeO)2MoCl3 and (MeO)4MoCl (according to 1HNMR structure 9 or 10 and 11 or 12, respectively) the complexes obtained by the reactions (MeO)2MoCl3 + 2 Me3Al and (MeO)4MoCl + 2 Me3Al are paramagnetic, indicating the expected absence of a MoMo bond. The 1HNMR spectrum of the reaction mixture obtained by treating the MoVI derivative MoO2Cl2 with 2 Me3Al in THF shows various signals for μCH2 groups, whereas signals of t‐CH2 ligands are missing (t = terminal). In analogy to 1 the carbonyl‐olefinating activity of the MoAl and WAl reagents is activated by the addition of 2 equiv. of HMPA. Treatment of PhCOCH2NEt2 (19) with {MoO2Cl2 + 2 Me3Al} leads to carbonyl olefination with formation of 20 and also to α‐methylation with formation of PhCOCH(Me)‐NEt2 (21), pointing to the intermediate formation of a t‐CH2Mo ligand. {MoO2Cl2 + 2 Me3Al + 2 HMPA} has found to be the best reagent for the carbonyl olefination of aldehydes, whereas {WOCl3(THF)2 + 2 Me3Al + 2 HMPA} was optimal for ketones. In 1:1 reactions both reagents normally give better yields than the Tebbe reagent. By applying (WOCl3(THF)2 + 2 Me3Al} and {MoO2Cl2 + 2 Me3Al} on ketones 16–18 an interesting neighbour group effect of electron donor atoms in the δ position to the keto group was observed.
Relative Reactivities of Alkyl Chlorides under Friedel‐Crafts Conditions
Authors: Dau‐Schmidt Jan‐Peter , Mayr Herbert 
Published: July 2007

AbstractCompetition experiments have been performed to determine the relative reactivities of 23 alkyl chlorides toward allyltrimethylsilane in the presence of catalytic amounts of ZnCl2.The krel scale spans over 11 orders of magnitude from 1‐adamantyl chloride (least reactive) to bis(p‐methoxyphenyl)methyl chloride (most reactive compound). A fair correlation between the alkylating ability and the SN1 reactivity in solvolysis reactions is found, thus providing a quantitative basis for our long‐standing working hypothesis that Lewis acid‐catalyzed additions of alkyl halides to CC multiple bonds only yield 1:1 products if the reactants ionize faster than the products. Trityl chlorides do not follow this correlation and are 105 times less reactive than predicted from their SN1 reactivities.
(1α,2α, 7α,8α,12α,17α,18α,19α)‐Heptacyclo[17.3.1.18,12.05,23.06,18.07,17.016,24]‐tetracosa‐5(23),16(24)‐dien, ein hyperstabiles Alken
Authors: Boldt Peter , Köpper Holger , Trog Rolf‐Stefan , Döring Detlev , Jones Peter G. 
Published: July 2007

(1α,6α,7α,8α,12α,17α,18α,19α)‐Heptacyclo[17.3.1.18,12.05,23.06,18.07,17.016,24]tetracosa‐5(23),16(24)‐diene, a Hyperstable AlkeneHydrogenation of the cis‐photodimer 1 of acenaphthylene yields the title compound 2, which, though still containing two double bonds, undergoes no further hydrogenation or reaction with bromine for steric reasons. The cyclobutane ring of 2 shows strong steric distortions as revealed by X‐ray analysis as well as by force‐field and semiempirical MO calculations.
Syntheses and Properties of New Quinone‐Bridged Diphenyl‐ and Tetraphenylporphyrins
Authors: Staab Heinz A. , Carell Thomas , Döhling Annelie 
Published: July 2007

AbstractSyntheses and spectroscopic properties of the porphyrin‐quinone cyclophanes 1, 2 and 3 of which structural and/or conformational studies have recently reported[1] are described. Physical properties related to photoinduced electron‐transfer reactions like redox potentials, absorption and emission spectra were determined for these compounds.
Zinc Complexes of Porphyrin‐Quinone Cyclophanes: Syntheses, Structures and Electron‐Transfer‐Related Properties
Authors: Staab Heinz A. , Anders Claus Krieger, Christine , Rückemann Andreas 
Published: July 2007

AbstractIn order to increase the driving force for photoinduced electron‐transfer reactions of porphyrin‐quinone cyclophanes, the zinc complexes 3a‐e and 4a‐e were prepared from the corresponding cyclophanes of the 1 and 2 series. Electron‐transfer‐related properties like redox potentials and fluorescence spectra were determined for 3a‐e and 4a‐e. The X‐ray structure analysis of 4a indicates that for the very fast and solvent‐independent electron transfer in these systems a specific mechanism involving an interaction of a quinone carbonyl group with the zinc might be considered as an alternative to through‐space electron‐transfer.
Gas‐Phase Kinetics of the Pyrolysis of Some 3,3‐Dimethyl‐1‐(trimethylsilyl)‐cyclopropenes — Unexpected Product Distribution in the Cyclopropene Rearrangement
Authors: Walsh Robin , Untiedt Sven , Meijere Armin De 
Published: July 2007

AbstractThe gas‐phase pyrolyses of 1,3,3‐trimethyl‐2‐(trimethylsilyl)‐cyclopropene (9), 3,3‐dimethyl‐1,2‐bis(trimethylsilyl)cyclopropene

Reactant
log (A/s−1)
Ea/kj mol−1
(kcal mol−1)

9
13.41 ± 0.22
192.1 ± 2.5
(45.9 ± 0.6)

10
13.54 ± 0.19
184.4 ± 2.1
(44.1 ± 0.5)

11
12.17 ± 0.38
124.6 ± 3.1
(29.8 ± 0.7)

(10), and 3,3‐dimethyl‐1‐(methylthio)‐2‐(trimethylsilyl)cyclopropene (11) have been studied, and the pressure‐independent Arrhenius parameters listed in the table were obtained. All three rearrangements are homogeneous, first‐order and unimolecular reactions. Rather surprisingly all reactions give the corresponding isomeric allenes as the main products. Amongst possible mechanisms discussed, 10 is proposed to react via a cyclopropylidene intermediate, whilst the results for 9 and 11 throw light on the relative importance of the diradical‐ and vinylcarbene‐type intermediates produced by cyclopropene ring opening.
Übergangsmetall‐Silyl‐Komplexe, 48. Synthese neuartiger heteronuklearer Silyl‐Zweikernkomplexe (OC)3(R3Si)Fe(μ‐PR′R″)Pt(1,5‐COD)(Fe‐Pt), Phosphan‐Austauschreaktionen an (OC)3 (R3Si)Fe(μ‐PR′R″)Pt(PPh3)2(Fe ‐ Pt) und Darstellung der Dihydrido‐Komplexe [(OC)3Fe(μ‐PPh2)(μ‐H)2Pt(PR3)2][BF4](Fe ‐ Pt)
Authors: Knorr Michael , Stährfeldt Thomas , Braunstein Pierre , Reinhard Georg , Hauenstein Peter , Mayer Brigitte , Schubert Ulrich , Khan Saeed , Kaesz Herbert D. 
Published: July 2007

Transition Metal Silyl Complexes, 48[1]. ‐ Synthesis of the New Heterobimetallic Dinuclear Silyl Complexes (OC)3(R3Si)‐Fe(μ‐PR′R″)Pt(1,5‐COD)(Fe‐Pt), Phosphane Exchange Reactions of (OC)3(R3Si)Fe(μ‐PR′R″)Pt(PPh3)2(Fe‐Pt), and Preparation of the Dihydrido complexes [(OC)3Fe(μ‐PPh2)(μ‐H)2Pt(PR3)2][BF4](Fe‐Pt)The dinuclear, silyl‐substituted complexes (OC)3(R3Si)Fe(μ‐PR′r″)Pt(1,5‐COD) (1) [μ‐PR′R″ = PPh2, PCY2, PHPh; SiR3 = SiPh3, Si(OMe)3] were prepared in high yields by the oxidative addition of the hydrido complexes (OC)3(PHR′R″)Fe(H)‐SiR3 to Pt(1,5‐COD)2. Upon reaction of (OC)3(R3Si)Fe(μ‐PR′R″)Pt(PPh3)2 [μ‐PR′R″ = PPh2, PHCy; SiR3 = SiPh3, SiPh2Me, SiPhMeCl, Si(OMe)3] with two equivalents of PR (PMe3, PBu3, PEt3) or with one equivalent of chelating di‐phosphanes (vdpp, dppe, dppm) both PPh3 ligands are displaced, and (OC)3(R3Si)Fe(μ‐PR′R″)Pt(PR)2 or (OC)3(R3Si)‐Fe(μ‐PR′R″)Pt[(PPh2)2X] (X = CCH2, C2H4, CH2) are formed, respectively. When one equivalent of PMe3 is used, only the PPh3 ligand trans to the μ‐PPh2 bridge is substituted, and (OC)3(Ph3Si)Fe(μ‐PPh2)Pt(PPh3)(PMe3 is formed. The 1,5‐COD ligand in 1 is displaced by P(OR)3 to give (OC)3‐(Ph3Si)Fe(μ‐PPh2)Pt[P(OR)3]2 (R = Me, Ph). The complexes (OC)3(Ph3Si)Fe(μ‐PPh2)Pt(PMe3)2and (OC)3(Ph3Si)Fe(μ‐PPh2)Pt[(PPh2)2CCH2] were characterized by X‐ray structure analysis. The short Fe‐Si distances [233.0(2) and 235.6(3) pm] and the infrared v(CO) absorptions indicate that the Fe‐Pt bonds are quite polar. Protonation of (OC)3(Me2‐PhSi)Fe(μPPh2)Pt(PPh3)2 with CF3COOH gives the hydrido‐bridged complex [(OC)3(Me2PhSi)Fe(μ‐PPh2)(μ‐H)Pt‐(PPh3)2][O2CCF3]. Upon addition of an excess of HBF4 · Et2O to (OC)3(R3Si)Fe(μ‐PPh2)Pt(PPh3)2 (R = Ph, OMe), (OC)3‐Si)Fe(μ‐PPh2)Pt[Pt[P(OMe)3]2 or (OC)3(Ph2MeSi)Fe(μ‐PPh2)‐Pt(dppe) R3SiF is split, and the corresponding μ‐dihydrido complexes [(OC)3Fe(μ‐PPh2)(μ‐H)2Pt(PR3)2][BF4] are obtained.
Synthesis and Characterization of Phthalocyanines Containing Four 14‐Membered Tetraaza Macrocycles
Authors: Koçak Makbule , Güek Ayşegül , Gül Ahmet , Bekaroǧlu Özer 
Published: July 2007

AbstractMetal phthalocyanines (M = Cu, Ni, Co, SnCl2) 3–6 containing four 14‐membered tetraaza macrocycles have been prepared. Detosylation of the aza functions has provided donor sites for binding four Ni2+ ions giving a pentanuclear complex which is extremely soluble in polar solvents. The mass spectrum of the [hexadecakis(N‐p‐tosyl)‐tetrakis‐macrocycle‐phthalocyaninato]copper(II)3 is described
Thermal and Photochemical Rearrangement of 3‐Substituted 2‐Methylbenzofuran Epoxides and Their Valence‐Isomeric Quinone Methides
Authors: Adam Waldemar , Käb Günther , Sauter Markus 
Published: July 2007

AbstractThe dimethyldioxirane oxidation of the 3‐substituted 2‐methylbenzofurans 1 [1a: 3(E)‐styryl, 1b: 3‐acetoxy, 1c: 3‐(tert‐butyldimethylsilyloxy)] is reported. Only quinone methide 3a, none of the benzofuran epoxides 2a–c, could be detected by 1H‐ and 13C‐NMR spectroscopy at low temperature (−30°C), which on photoisomerization led to chromene 7a. The benzofuran‐3‐ones 5b, c and the α‐diketone 6c are presumably formed by thermal isomerization of the transient benzofuran epoxides 2b, c and quinone methide 3c.
Transanulare Wechselwirkungen in difunktionellen mittleren Ringen, 4. Spektroskopische und theoretische Untersuchungen an bicyclischen Boraalkenen
Authors: Rademacher Paul , Wiesmann Reinhard F. 
Published: July 2007

Transanular Interactions in Difunctional Medium Rings, 4[1]. — Spectroscopic and Theoretical Investigations on Bicyclic BoraalkenesThe 3‐borabicyclo[3.3.1]nonene and ‐nonane derivatives 3 and 5 with an endo‐ or exocyclic CC double bond, respectively, have been synthesized as well as the corresponding monofunctional compounds bicyclo[3.3.1]non‐2‐ene (1), 3‐methylenebicyclo[3.3.1]nonane (2), and the 3‐borabicyclo[3.3.1]nonanes 4. The compounds were investigated by PE, 13C‐ and 11B‐NMR spectroscopy. In addition, molecular mechanics and semi‐empirical quantum‐chemical calculations have been performed. Although the transanular distances in both groups of compounds vary little, the difunctional compounds with an exocyclic double bond (5) show distinct transanular interactions whereas in the compounds with an endocyclic double bond (3) such effects are virtually absent. While the theoretical methods proved to be insufficient for the investigation of transanular interactions, PE and 11B‐NMR spectroscopy were well suited for this study.
On the Reaction of 1‐Aza‐2‐azoniaallene Salts with Acetylenes
Authors: Wang Quanrui , Al‐Talib Mahmoud , Jochims Johannes C. 
Published: July 2007

Abstract1‐Aza‐2‐azoniaallene cations 3, prepared in situ from geminal chloro(alkylazo) compounds 2, react with acetylenes 4 to give either 1H‐pyrazolium salts 6 or 4H‐pyrazolium salts 7 or mixtures of both. 4H‐Pyrazolium salts with a hydrogen atom attached to C(4) rearrange to the protonated 1H‐pyrazoles 8, from which the free bases 9 are obtained upon treatment with aqueous NaOH. According to AM1 calculations the cycloaddition of acetylenes to 1‐aza‐2‐azoniaallene cations is a concerted process, which can be classified as a “1,3‐dipolar cycloaddition with reverse electron demand”. The cycloaddition forming the intermediates 5 is followed by an [1,2] alkyl shift to furnish the final products 6–8. The direction of the [1,2] shift has been found to be governed by subtle steric effects.
Synthesis and Structural Characterization of the Bent Nitrosyl Organometallic Complex [NBu4][Pt(C6Cl5)2Cl2(NO)]
Authors: Forniés Juan , Menjón Babil , Sanz‐Carrillo Rosa María , Tomás Milagros 
Published: July 2007

AbstractThe title complex has been prepared in 36% yield by reaction of [NBu4]2[trans‐Pt(C6Cl5)2Cl2] with NOClO4 (1:1) in CH2Cl2. The anion exhibits an almost tetragonal‐pyramidal geometry (X‐ray analysis), the platinum atom being virtually located in the basal plane and the NO ligand occupying the apical position. The PtNO unit is bent [119.5(8)°].
Alkyleisen‐ und Alkylcobalt‐Reagenzien, IX. Umlagerung aliphatischer terminaler Epoxide zu Methylketonen durch Eisenalkyl‐Reagenzien statt durch Co2(CO)8 oder Edelmetallkatalysatoren
Authors: Kauffmann Thomas , Neiteler Christel , Neiteler Gabriele 
Published: July 2007

Alkyliron and Alkylcobalt Reagents, IX[1]. — Rearrangement of Aliphatic Terminal Epoxides to Methyl Ketones by Iron Alkyl Reagents instead of Co2(CO)8 or Noble Metal CatalystsThe highly selective rearrangement of aliphatic terminal epoxides to methyl ketones, hitherto possible only with Co2(CO)8 or noble metal catalysts, occurs smoothly with Me4‐FeLi2, Me3FeLi, or the catalytic systems [RLi + 2.5 mol% FeCl3] (R = Me, Bu). This was demonstrated by the rearrangement of 1‐decene oxide (1) to 2‐decanone (2) (yield 80–81%; Table 1) and 6‐bromo‐1‐hexene oxide (5) to 6‐bromo‐2‐hexanone (6) (yield 78%, Me4FeLi2 applied only). The competition reaction of Me4FeLi2 with 1 and 2‐octanone (8) (mole ratio 0.5:1:1) led to 87% 2‐methyl‐2‐octanol (9) and not to the rearrangement 1 → 2. This indicates that Me4FeLi2 ‐ in contrast to the opposite behavior of organo cuprates ‐ reacts faster with ketones than with the aliphatic terminal epoxides. By treatment of 1 with methyl derivatives of MnII, CoII, and NiII or with Bu4FeLi2 (Table 2) other products (3, 4) besides 2 were formed. The rearrangement of 1 with Me4FeLi2 is assumed to start with an oxidative addition and yields 2 as its Li or Fe enolate (trapped with acetanhydride to give 64% of 20) after reductive elimination of CH4. The catalytic rearrangement of 1 with [MeLi + 0.25 mol% FeCl3] very probably occurs in an analogous manner with an super‐ate complex Me4FeLi2(MeLi)n as the active species and the Li enolate of 2 as end product (Scheme 4). The aromatic terminal epoxides styrene oxide and α‐methylstyrene oxide give various products in the reaction with Me4FeLi2 or Me3FeLi, including the deoxygenation products styrene and α‐methylstyrene. These products are exclusively formed on treatment of the epoxides with Me4MnLi2. (Prepared, hitherto in the literature not described compounds: 7 and 10–15.)