10,10‐Bis(dimethylamino)nonafulven

Herrn Prof. Dr. Huns Nitschmann zum 80. Ceburtstag gewidnict (25.11.87) Synthesis and NMR Spectra of Nonafulvene and Comparison with 10-PhenylnonafulveneExperimental procedures for the reaction of cis,cis,ci.s,trans-cyclononatetraenide (ccct -CNT-; see 4) with bromomethyl acetate (la, R = H, X = Br) to give (cyclononatetraeny1)methyl acetate (Sa; 84% yield) as well as for the base-induced elimination of HOAc from 5a to give nonafulvene (6a; 44% yield) are described. Spectroscopic as well as chemical evidence for 6a and 6b is presented. An approximate high-field-NMR analysis of 6a and 6b has been completed. The results are in favour of a fast interconversion of the type 6A*6B /Scheme 4 ) . and supported by the MNDO-optimised geometry of 6a. The first X-ray analysis of a cyclononatetraene (i.e. of Sb) has been accomplished: 5b is a polyolefinic molecule with largely alternating bond lengths and with a nine-membered ring deviating strongly from planarity.1. Einleitung. -Essigsaure-(a-halogenalky1)ester 1 sind aus aliphatischen und aromatischen Aldehyden sowie Acetyl-chlorid oder Acetyl-bromid bei Katalyse mit Lewis-Sburen in einer einfachen Eintopfreaktion zuganglich [5]. Unter optimalen Reaktionsbedingungen lassen sich Nebenprodukte weitgehend vermeiden [6] und oft fast quantitative Ausbeuten erzielen [513). Die bifunktionellen Carbonyl-Derivate besitzen zwei Abgangsgruppen unterschiedlicher nucleofuger Eigenschaften und gehen naturgemass im basischen Milieu keine Nebenreaktionen des Aldol-Typs ein. Wir haben diese Vorteile bei der Entwicklung einer allgemeinen Pentafulven-Synthese ausgenutzt (Schema 1 ) und ge-

Section: Is)unclassified

Synthese und NMR‐Spektren von Nonafulven sowie Vergleich mit 10‐Phenylnonafulven

Fürrer

Bönzli

Frey

et al. 1987

“…Im "C-NMR-Spektrum von In in CDCI, sind bei 'H-Rauschentkopplung die s der exocyclischen CH2-Gruppen (37,7 ppm) sowie von C(9) (122,2) und C(10) (143,4) leicht zu lokalisieren. Die Zuordnung von C(l)/C(S) (127, 9), C(2)/C(7) (124,6), C(3)/C(6) (127,9) und C(4)/C(5) (126,6 ppm) erfolgt durch 'off-resonance'-Entkopplungen im 'H-Bereich. Die vier Paare aquivalenter Ring-C-Atome absorbieren im engen Interval1 von 127,9-124,6 ppm, also sehr ahnlich wie die Ring-C-Atome von l a (130,6-126,6 ppm).…”

Section: )unclassified

“…Das 10,lO-Bis(dimethy1amino)nonafulven (lk) [9] sowie der elektronisch unverfalschte Grundkorper l a [ 1 11 zeichnen sich durch ein sehr unterschiedliches spektroskopisches Verhalten aus. Wahrend die 'Hund "C-NMR-Spektren von l a keine Losungsmittel-und Temperaturabhangigkeit aufweisen, wird das spektroskopische Verhalten von l k sehr ausgepragt durch Losungsmittel und Temperatur beeinflusst.…”

unclassified

Synthese neuer Nonafulvene

Sabbioni

Otter

Millar

et al. 1985

Nonafulvenes lc and 1m-S are prepared by the following methods: a) Elimination of AcOH from acetoxyalkyl-cyclononatetraenes (Scheme 2; lm); b) alkylation of nonafulvenolates (Scheme 3, lc, In); c) elimination of alcohol from di-and trialkoxymethyl-cyclononatetraenes (Scheme 5; lo, lp, lq); d) deprotonation of intermediary formed formamidiniumcyclononatetraenes (Scheme 6 ; tr, Is). Scope and limitations of these preparative sequences are discussed and compared with the corresponding pentafulvene syntheses. ') 2, Ted der Dissertation [4]. ' )Ted der Dissertation (51. 4,Postdoctoral fellow 1977/78. 5,Im folgenden wird all-cis -Cyclononatetraenid als CNT-, all-cis-Cyclononatetraen als CNT und cis,clr,cis,trons-Cyclononatetraenid als ccct -CNT-abgekurzt. ' ) Das Nonafulvenolat (bzw. Nonafulventhiolat) 4 befindet sich mit dem entsprechenden Acyl-CNT-(bzw. Thioacyl-CNT-) im Gleichgewicht, dessen Lage durch Substituenten, Solvens, Temperatur und Gegenion beeinflusst wird 1121. 44. Mitt. uber Fulvene, Fulvalene, 43.Mitt. [I]; Kurzmitteilungen 121 131.

“…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: 98%

“…Pentafulvenes were the first fulvenes to be discovered in 1900 by Thiele [2], and the yellow color of these compounds (lat. fulvus ¼ yellow) is responsible for the name of the whole family.A fter the first syntheses of substituted triafulvenes 1 [3]a nd of heptafulvenes 3 [4]itbecame usual to add the ring size as prefix to the name.The first simple member of the class of nonafulvenes 4 was isolated in 1969 [5].…”

mentioning

confidence: 99%

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

Neuenschwander

2015

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.