Stabilized and destabilized carbocations in the 1,6-methano[10]annulene series

2-Chloromethyl and 3-chloromethyl-1,6-methano[10]annulene systems solvolyze in methanol to give simple substitution products. Solvent effect studies and the special salt effect support the involvement of cationic intermediates stabilized by the 1,6-methano[10]annulene group. Rate data indicate that the degree of cation stabilization greatly exceeds that of naphthyl groups. B3LYP/6-31G computational studies also suggest that the cationic intermediates are greatly stabilized by the 1,6-methano[10]annulene. By way of contrast to these findings, solvolytic and computational studies indicate that the 11-(1,6-methano[10]annulenyl) cation is a destabilized analogue of the cycloheptatrienyl cation. There are no favorable interactions with the annulene ring. Distortions from planarity prevent charge delocalization as in the analogous aromatic cycloheptatrienyl cation.     

Syntheses and Properties of Donor/Acceptor Arylethynyl-Substituted 1, 6-Methano[10]annulenes

The stepwise palladium-catalyzed coupling of dibromo-1,6-methano[10]annulene derivatives to a phenyl-acetylene substituted by an electron-withdrawing group followed by coupling with a phenylacetylene possessing an electron-donating group allows the preparation of donor/acceptor systems which contain three aromatic moieties linked by ethynediyl bridges. The same type of cross-coupling starting from 2-ethynyl-1,6-methano[10]annulene and bromo-substituted azobenzene derivatives provides easy access to a new class of azo dyes. The properties of these compounds are compared to those of analogous compounds containing only benzene rings.     

Aromaticity and Homoaromaticity in Methano[10]annulenes

Aromaticity and neutral homoaromaticity have been evaluated in methano[10]annulenes systems, 1,4-methano[10]annulene (1), 1,5-methano[10]annulene (2), and 1,6-methano[10]annulene (3). C-C bond lengths indicate that 1 presents higher bond alternation than 2 and 3. The relative energies were determined at the B3LYP/6-311+G(d,p) level, and they pointed out that 3 is the most stable isomer. Strain energies, evaluated employing homodesmotic reactions, show the same order as the relative energies. Through a decomposition of strain energies, it could be concluded that the rings absorb more tension than the bridges. The changes in aromaticity were evaluated by magnetic susceptibilities, chiM, HOMA, NICS, and resonance energies, RE. HOMA, RE, and chiM indicate that 2 and 3 are strongly, and 1 is fairly, aromatic. NICS does not provide reliable results, due to interference of ring and bridge atoms. NBO analysis presents some interactions that suggest the existence of neutral homoaromaticity. GPA indices (evaluated at the B3LYP/6-31G* level) point out that homoaromaticity plays a relevant role only in 3. Moreover, this work is the first in the current literature that studies 1,4-methano[10]annulene (1).     

Neue 1,6-Methano[10]annulen-Derivate durch Umlagerungsreaktionen der Trimethylsilyl-Gruppe

New Derivatives of 1,6-Methano[10]annulene by Rearrangement of Trimethylsilyl Groups Oxidation of derivatives of trimethylsilyl-substituted bicyclo[4.4.1]undeca-1,3,5,7-tetraenes 1–3 leads to 1,6-methano[10]annulenes. In the case of 2 and 3a , rearrangement of the trimethylsilyl group takes place. This rearrangement can be used to prepare 2,9-disubstituted 1,6-methano[10]annulenes.     

Synthesen und Eigenschaften ethinylierter und trimethylsilylethinylierter Molekülsysteme mit 1,6-Methano[10]annulen-Partialstruktur

2-Trimethylsilylethinylated 1,6-methano[10]annulene1 a was obtained by reaction of 2-bromo-1,6-methano[10]annulene with trimethylsilylacetylene in the presence of bis-(triphenylphosphin-)-Pd (II) chloride and Cu(I) and also by reaction of 1,1-diiodo-2-(1,6-methano[10]annulene-2-yl)-ethene (2) withn-buthyl-lithium followed by hydrolysis.1 a reacts with 2N NaOH to 2-ethinyl-1,6-methano[10]annulene (1 b). 2,7- and 2,10-dibromo-1,6-methano[10]annulene can be substituted to give the trimethylsilylethinylated compounds3 a–6 a, which then can be transformed with 2N NaOH into the desilylated products3 b–5 b.

Wolfgang Kraus, Stuttgart-Hohenheim, mit den besten Wünschen in Freundschaft zum 60. Geburtstag gewidmet     

Nukleophile Addition von Lithiumorganylen an das N,N-Diethyl-10-(trimethylsilyl)-1, 6-methano[10]annulen-2-carboxamid

Nucleophilic Addition of Lithiumorganyles to N,N-Diethyl-10-(trimethylsilyl)-1,6-methano[10]annulene-2-carboxamide Reaction of lithiumorganyles with N,N-diethyl-10-(trimethylsilyl)-1,6-methano[10]annulene-2-carboxamide followed by quenching with H₂O or MeI yields 2,3-dihydro derivatives of 1,6-methano[10]annulene.     

简便合成3,3'-联-1,6-亚甲基桥[10]轮烯

以1,6-二甲酰基环庚三烯为原料通过10π电子环化反应等3步反应制备了3-溴代-1,6-亚甲基桥[10]轮烯, 通过3-溴代-1,6-亚甲基桥[10]轮烯的碱诱导的偶联反应, 简便地合成3,3'-联-1,6-亚甲基桥[10]轮烯, 并用NMR, MS等波谱进行了表征.     

Massenspektroskopische Fragmentierungsreaktionen. XX—Zur Frage der elektronenstoß-induzierten Carbenabspaltung

The electron impact induced decomposition of 1,6-methano[10]annulene and of its bridge substituted derivatives has been investigated in view of a possible climination of a carbene and formation of ionized naphthalene. While carbene elimination is not observed with the parent hydrocarbon (<0.5% rel. int.), it is a prominent fragmentation path for its 11-halogen and 11,11-dihalogen derivatives. Elimination of the bridge is observed also with 1,6-methano[10]annulenes carrying C-substituents at C-11. It cannot be determined, however, whether the neutral particle lost is a carbene or a rearranged species. The analogy between thermal and electron impact decomposition is commented upon.     

Carbene elimination from ionized methanoannulenes

Evidence is produced to demonstrate that loss of CH₂ from methanoannulenes is a multistep process initiated by a rearrangement yielding (at least in the case of 1,6-methano[10]annulene) the isomeric benzocycloheptenes. Loss of CF₂, however, apparently is a cheletropic reaction accompanied by rearomatization, thus giving rise to the formation of the molecular ion of naphthalene in the case of 11,11-difluoro-1,6-methano[10]annulene. These findings present further evidence for the parallel behaviour of the bridged annulenes regarding thermal transformations and fragmentation of the molecular ions.     

Vicarious nucleophilic substitution of hydrogen in nitro-1,6-methano[10]annulenes

Summary The 2- and 3-nitro-1,6-methano[10]annulenes and their 11,11-difluoro derivatives react with carbanions bearing leaving groups at the carbanionic center according to the Vicarious Nucleophilic Substitution of Hydrogen (VNS) scheme. The analogy between corresponding annulenes and naphthalenes with respect to reactivity is discussed.

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Vicarielle nucleophile Substitution von Wasserstoff in Nitro-1,6-methano[10]annulenen

Zusammenfassung 2- und 3-Nitro-1,6-methano[10]annulene und ihre 11,11-Difluoroderivate reagieren mit Carbanionen, die am carbanionischen Zentrum Abgangsgruppen aufweisen, nach dem Schema der vicariellen nucleophilen Substitution (VNS). Die Analogie zwischen entsprechenden Annulenen und Naphthalinen bezüglich ihrer Reaktivität wird diskutiert.

     

Synthesis and properties of tricyclo[6.4.1.0]trideca-1,3(6),7,9,11-pentaene

A new cyclobutene-fused 1,6-methano[10]annulene was synthesized by pyrolysis of the sulfone and sulfinate adducts of 3,4-bis(methylene)-1,6-methano[10]annulene and its physical and chemical properties were disclosed.     

Synthese neuer schwefel- und selen-haltiger ‘Donor-Akzeptor-stabilisierter’ Molekülsysteme mit zentraler bicyclo[4.4.1]undeca-4,6,8,10-tetraen-2,3-diyliden- oder Bicyclo[4.4.1]undeca-3,6,8,10-tetraen-2,5-diyliden-Gruppe

Synthesis of New Sulfur- and Selenium-Containing ‘Donor-Acceptor-Stabilized’ Systems with Central Bicyclo-[4.4.1]undeca-4,6,8,10-tetraene-2,3-diylidene- or Bicyclo[4.4.1]undeca-3,6,8,10-tetraene-2,5-diylidene Groups Syntheses of starting materials 3 – 55 and 8 and of the S- and containing 1,6-methano[10]annulene (=1,6-methanobicyclo[4.4.1]undeca-1,3,5,7,9-pentaene) derivatives 12, 13, 15 and 16 are described.     

Synthesen und chemisches Reaktionsverhalten neuer überbrückter Chinonderivate. Kupplungsreaktionen von Diazoniumsalzen mit 2-Methoxy-1,6-methano [10]annulen

Syntheses and Chemical Properties of New Bridged Quinone Derivatives. Coupling Reactions of Aryldiazonium Salts with 2-Methoxy-1,6-methano[10]annulene Coupling of 2-methoxy-1,6-methano[10]annulene (3) with the aryldiazonium salts 4a-4i yields the quinone hydrazones 5a-5i. The spectroscopic properties of these products are described. The reaction of 3 with 4-nitrophenyldiazonium tetrafluoroborate buffered with sodium acetate in dry methanol yielded after chromatographic separation the azo derivative 7 on the one hand and a mixture of the valence tautomers 8a and 8b on the other.     

Synthesen,chemische und elektrische Eigenschaften von Tetrathiafulvalen mit 1,6-Methano[10]annulen-Partialstruktur und von Chalcogendiimid-derivaten

Syntheses, Chemical and Electrical Properties of Tetrathiafulvalene with a 1,6-Methano[10]annulene Moiety and of Chalcogendiimide-Derivatives The synthesis of the tetrathiafulvalene 6 has been described: the reaction of 1 with the benzenedithoil 2 yielded the bis-dithioacetal 3 of 1,6-methano[10]annulene-dicarbaldehyde 1 . The oxidation of 3 in the presence of HBF₄ in Et₂O yielded the salt 4 , elimination of a hydride anion with triphenylmethylium tetrafluoroborate the salt 5 , and elimination of a proton in 5 with Et₃N the tetrathiafulvalene 6 with a 1,6-methano[10]annulene moiety. The spectroscopic and electrochemical properties of 6 are described, and also the syntheses and properties of charge-trasnfer complexes 7 and 8 , including the properties of electric conductivity of 7 and 8 . the syntheses of 9-13 are reported and also their spectroscopic properties.     

Disubstituted 1,6-methano[10]annulene derivatives for use in organic light-emitting diodes

Bis(carbazolylphenyl) and bis(diphenylaminophenyl) derivatives of 1,6-methano[10]annulene, which is luminescent material and contains seven-membered rings, are synthesized. The bis(phenylcarbazole) derivative 3 have high melting point and glass transition temperature. Electroluminescence characteristics of organic light-emitting diodes using these methano[10]annulenes were investigated.     

Synthesen und chemische Reaktionen neuer Chinonderivate mit 1,6-Methano[10]annulenpartialstruktur oder ihrer Valenztautomeren

Syntheses and Chemical Reactions of New Quinone Derivatives with 1,6-Methano[10]annulene Fragments or their Valencetautomers The coupling of 2-Methoxy-1,6-methano[10]annulene with aryldiazonium salts leads to the corresponding quinone hydrazones. These compounds undergo reduction with LiAlH₄, condensation with hydrazines and hydrazides and alkylation at the carbonyl O-atom or the hydrazone N-atom.     

Neue Synthesewege zu aminosubstituierten 1,6-Methano[10]-annulenderivaten

Summary Syntheses of 1,6-methano[10]annulene-phthalimido-derivatives4,5 a,5 b,5 c, and6 are described, starting from 2,7-disubstituted 1,6-methano[10]annulenes; derivative8 was prepared from 2-bromo-11,11-difluoro-1,6-methano[10]annulene (9).4 and8 can be changed to the 2-amino-1,6-methano[10]annulenes10 and11.

Herrn Professor Siegfried Hünig, Würzburg, mit den besten Wünschen zum 70. Geburtstag gewidmet     

Practical dihydroxylation and C–C cleavage of unsaturated fatty acids

Unsaturated fatty acids [C₈H₁₇CH=CH(CH₂)_nCO₂H] (n=7, 11) acids are cleanly dihydroxylated by hydrogen peroxide in the presence of catalytic amounts of H₂WO₄. Under molecular oxygen, in the presence of catalytic amounts of N-hydroxyphthalimide and Co(acac)₃, the diols resulting from erucic (n=11) and oleic (n=7) acid undergo C–C cleavage.     

酸功能化离子液体催化合成聚缩醛二甲醚

对以酸功能化离子液体[Hnmp]HSO4、[Hnmp]H2PO4、[Hnmp]PTSA和[PyN(CH2)3SO3H]HSO4催化三聚甲醛和甲醇缩合制备聚缩醛二甲醚(PODEn,n1)的反应进行了研究,考察了催化剂用量、物料配比、温度和时间等对反应活性的影响。结果表明,离子液体的催化活性与其酸性相关。[PyN(CH2)3SO3H]HSO4具有较高的催化活性;当[PyN(CH2)3SO3H]HSO4的用量为2.0%、甲醇和三聚甲醛的物质的量比为2.0、反应温度110℃、反应压力2.0 MPa、反应时间6 h时,三聚甲醛的转化率和PODE3~8的选择性分别为97.69%和32.54%。反应结束后,[PyN(CH2)3SO3H]HSO4与产物可自动分成两相。     

2,5-Chinonmethide des 1,6-Methano[10]annulens mit S,N- und N,N-Acylketenacetal Struktur

2,5-Quinonemethides of 1,6-Methano[10]annulene with the Structures of S,N- and N,N-Acylketene Acetals Investigation on the chemical reactivities of 2-(tert -butoxy)-1,6-methano[10]annulene and the syntheses of the compounds 2, 4, 6–8, 11, 13–22 are described; the results of ¹H- and ¹³C-NMR-spectroscopic measurements are reported.