Methylvinylfulvene

Neuenschwander, Markus; Meuche, Doris; Schaltegger, H.

doi:10.1002/hlca.19640470412

Cited by 35 publications

(30 citation statements)

References 6 publications

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“…6 shows the 1 H-NMR-spectrum of sesquifulvalene (19a)at270 MHz in C 6 D 6 at À 108 [43] 19 ). Thei nteresting part was the AA'BB'-system of the protons of the fivemembered ring at 6.32 and 6.27 ppm which could be analyzed to give vicinal coupling Helv eticaChimica Acta -V ol.…”

Section: 3synthesis Of Heptafulvene (3a)mentioning

confidence: 99%

“…First Attempts towards the Synthesis of Triafulvene,C alicene and Nonaheptafulvalene.S imilarly to the synthesis of heptafulvene (3a)a nd sesquifulvalene (19), triafulvene (1a)a sw ell as calicene (17)c ould be made available by acylation of cyclopropenone [6], subsequent reaction with methyl lithium and cyclopentadienide, respectively,and final AcOH elimination. In fact, cyclopropenone reacted easily with acetyl fluoroborate at À 788,b ut the hereby formed acetoxy-cyclopropenylium fluoroborate underwent disproportionation into BF 3 ,a cetyl fluoride and cyclopropenone.A lthough cyclopropenone precursors 34a þ 34b reacted with methyl lithium or sodium cyclopentadienide (Scheme 8), elimination experiments 35 !…”

Section: 3synthesis Of Heptafulvene (3a)mentioning

confidence: 99%

“…4 shows all the combinations between 3-, 5-, 7-and 9-membered rings.T here are fulvalenes with two identical rings (triafulvalene (11)t ill nonafulvalene (14)),f ulvalenes 15 and 16 with rings of similar electron demand and fulvalenes (17 till 20)with rings of inverse polarization. Examples of that type are pentatriafulvalene (17)[ synonym calicene 5 )] as well as heptapentafulvalene (19)[ synonym sesquifulvalene]w hose dipolar forms (Fig.4,r ight)a re suggesting that both rings are supporting each other electronically.…”

mentioning

confidence: 99%

“…2b the yield of pure 6-vinylfulvene (2b)could be increased to 10% which allowed the isolation and spectroscopic structure elucidation [18]. Furthermore, 2b as well as its methyl derivatives were synthesized according to the Thiele procedure [19]which gave 6-vinylfulvenes only in low yields.…”

mentioning

confidence: 99%

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Low‐Temperature Olefin Syntheses in View of Parent Fulvenes and Fulvalenes

Neuenschwander

2015

Helvetica Chimica Acta

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Parent fulvenes and fulvalenes are thermallyu nstable cross-conjugated olefins for which lowtemperature syntheses are indispensable. In this review 5syntheses (inthe temperature range between À 100 and À 108)are discussed:1. Reaction of sodium cyclopentadienidew ith 1-acetoxy-1-chloroalkanes or 1-acetoxy-1-bromoalkanes (26)gives acetoxy-alkyl-cyclopentadienes (27)which are easily converted to pentafulvenes (2)by low-temperature HOAc-elimination with NEt 3 .T his synthesis has been applied to parent pentafulvene (2a), heptafulvene(3a), nonafulvene (4a)a nd sesquifulvalene (19a)(Schemes 8 -11).2. Based on an early quantitative oxidative coupling of cyclononatetraenide (8)t og ive dihydrononafulvalene (38)( Scheme 10), ag eneral synthetic plan for fulvalenes has been outlined (Scheme 11)a nd applied to the synthesis of pentafulvalene (12), nonapentafulvalene (16)a nd nonafulvalene (14). Several applications of oxidative couplings of Hückel anions are discussed (Schemes 20 and 21).3. Tr ifunctional cyclopropanes 67 (inm ost cases 1,1-dibromo-2-X-cyclopropanes) are attractive precursors of parent triafulvene (1a)a nd calicene (17)(Scheme 18). Contrary to classical procedures they are transformed into nucleophiles (67 ! 68)b yh alogen-lithium exchange,m ethylation( 68 ! 69) and HBr-eliminationt og ive 1-methylidene-2-X-cyclopropaneso ft ype 71.B ys ubsequentH Xeliminationtriafulvene (1a)has been synthesized and trapped as a[4þ2]-cycloadduct 73 (Scheme 20). Furthermore,c alicene precursors 77 are available by using cyclopentenone as an electrophilic cyclopentadiene equivalent.4. Similarly,1 -lithio-1-bromo-2-X-cyclopropanes 68 are directly transformed into triafulvalene precursors 81 (Scheme 26)b yanovel CuCl 2 -catalyzed oxidative coupling.5. In view of the synthesiso fp arent triafulvene( 1a), triafulvalene( 11)a nd calicene (17), retroDielsÀAlder reactionso fs table precursors -p repared by low-temperature reactions( described in chapters 3 and 4)-have been explored.

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Section: 3synthesis Of Heptafulvene (3a)mentioning

confidence: 99%

Section: 3synthesis Of Heptafulvene (3a)mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Low‐Temperature Olefin Syntheses in View of Parent Fulvenes and Fulvalenes

Neuenschwander

2015

Helvetica Chimica Acta

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“…[10] Subsequent deprotonation was cleanly effected by treatment with potassium hexamethyldisilazide (3) in diethyl ether at 0 8C. The resulting potassium butadienylcyclopentadienide (4) was then transmetalated to the zirconium center by treatment with zirconium tetrachloride in THF at À78 8C to yield 5 as a yellow solid (78 % isolated; Scheme 2).…”

Section: Dedicated To Professor Manfred Christl On the Occasion Of Himentioning

confidence: 99%

Formation of an Organometallic Ladderane Derivative by Dynamic Topochemical Reaction Control

Paradies¹,

Greger²,

Kehr³

et al. 2006

Angew Chem Int Ed

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Bildung eines metallorganischen Ladderan‐Derivats durch eine dynamische topochemische Reaktion

Paradies¹,

Greger²,

Kehr³

et al. 2006

Angewandte Chemie

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Professor Manfred Christl zum 65. Geburtstag gewidmetTopochemische Reaktionen eröffnen einzigartige Möglich-keiten für die Kohlenstoff-Kohlenstoff-Verknüpfung.[1] Typische Beispiele sind die Bildung von Cyclobutanen und Ladderanen [2, 3] (anellierten Oligocyclobutanen) durch photochemisch induzierte [2+2]-Cycloadditionen zwischen substituierten Alkenen, die in einem Kristallgitter, [4] an starren organischen Gerüsten [5] oder durch Assoziation über Wasserstoffbrücken [6] in einer geeigneten räumlichen Orientierung vorliegen. Die Bildung von Cyclobutanringen durch photochemische [2+2]-Cycloaddition wird oft dann beobachtet, wenn sich die beteiligten p-Systeme nahe genug sind ( 3.6 ) -bei größerem Abstand der einzelnen Oligo-enKetten im Kristall oder in Lösung findet diese Reaktion nicht mehr statt.[5] Eine Alternative könnte sich dadurch eröffnen, dass man Butadienylsubstituenten an den Cyclopentadienyl(Cp)-Ringen eines gewinkelten Metallocens anbringt (V < 1808, siehe Schema 1). In solchen konformativ flexiblen Systemen [7] könnten die Dienylsubstituentenpaare einander nahe genug kommen, um Cyclobutane oder gar Ladderane durch photochemische [2+2]-Cycloadditionen zu bilden.Ausgehend von Arbeiten zu den verwandten ansa-Metallocenen [8] gelang uns jetzt die Bildung eines metallorganiSchema 1.

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Methylvinylfulvene

Cited by 35 publications

References 6 publications

Low‐Temperature Olefin Syntheses in View of Parent Fulvenes and Fulvalenes

Low‐Temperature Olefin Syntheses in View of Parent Fulvenes and Fulvalenes

Formation of an Organometallic Ladderane Derivative by Dynamic Topochemical Reaction Control

Bildung eines metallorganischen Ladderan‐Derivats durch eine dynamische topochemische Reaktion

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