Bicyclo -2,5-octadiene

Chemical Class Dibenzo-bicyclo-octadiene derivative... 

Concurrent with this work was reported the isolation by recrystallization of the air-sensitive trans,cis,cis,trans-, cis,cis,cis,cis- and trans,cis,cis,cis-2,A,6, - tC2i-tetraenes and their conversion to the cyclic trienes and to the same bicyclo octadienes along with quantitative data on all conversions (Scheme 9.49). ... 

A number of CSl additions have been shown to produce much less stable j5-lactams. The azetidinone (51) was isolated from the reaction of cyclo-hexadiene with CSI for five minutes at room temperature, while after thirty hours (52) was formed, and the reaction in refluxing chloroform gave (53). Analogous reactions with bicyclo-octadiene did not involve the tautomeric cyclo-octatriene. Initial formation of a 1,4-dipolar intermediate was... 

A useful compilation of 220 MHz n.m.r. data of substituted bicyclo[3,2,l]octan-6-ones has been published. The bicyclo[3,3,0]octyl cation appears to be implicated in the isomerization of bicyclo[3,2,l]oct-2-ene over SiOj-PaOj at 250 °C as deduced from the scrambling of label in [3- C]-tagged material and the distribution of label in the product, namely bicyclo[3,3,0]oct-2-ene. It has been found that 2,4-diphenyl-bicyclo[3,2,l]octa-2,6-diene (630) and its 6,7-dihydro-derivative undergo base-catalysed hydrogen-deuterium exchange at C-4 at essentially the same rate. Hence, the phenyl groups result in the total elimination of charge delocalization from C-4 to the C-6-C-7 double bond that is found in the unsubstituted bicyclo-octadiene. The... 

The structure of asatone has been revised to that indicated by formula (915) intramolecular photocycloaddition of the bicyclo-octadiene double bond to the enone double bond of (915) yields isoasatone, a cage molecule, which co-occurs with asatone in the plant. " ... 

The cyclo-octatriene-bicyclo-octadiene valence isomerism (357) (358)... 

Studies of solvolysis of similar polyfluonnated polycyclic aromatic systems, such as 2,3-(tetrafluorobenzo)bicyclo[2 2 2]octadienes and related compounds, proved the ionic mechanism of this rearrangement [55, 36, 37] (equation 9) Possible nonclassical carbonium ion involvement has been discussed [5S, 39, 40, 41]... 

Base-induced rearrangement of bicyclo[2.2.2]octane oxide 67 gives predominantly bicyclo[2.2.2]octanone 68 (Scheme 5.15), which once again indicates that close proximity between the carbenoid center and the C-H bond into which it may insert is important if such an insertion is to occur [30]. In comparison, the sense of product distribution is reversed for the related substrate bicyclo[2.2.2]octadiene oxide 70 on treatment with LDA [15, 22], alcohol 72 being the favored product. 

In siedendem Diathylather wird in 69%iger Ausbeute Dibenzo-S-aza-bicyclo[5.1,0]octadien-(2,5) gebildet, das durch Lithiumalanat ebenfalls zum prim. Amin (38% d.Th.) umgelagert werden kann. 

Jeweils zwei Produkte werden bei der Elcktrolyse mit 1, ty-Dihalogenidcn isoliert mit 1,2-Dichlor-athan erhalt man aus Anthracen 9-(2-Chlor-athyl)-9,10-dihydro-anthracen (I) und Dibenzo-bicyclo[2.2.2]octadien (II)1 ... 

It was pointed out earlier that a Cope rearrangement of 1,5-hexadiene gives 1,5-hexadiene. This is a degenerate Cope rearrangement (p. 1380). Another molecule that undergoes it is bicyclo[5.1.0]octadiene (105). At room temperature the NMR... 

A somewhat milder route which appears to be devoid of the complications of isomerization is the retro-Diels-Alder reaction of bicyclo [2.2.2] octadienes, frequently substituted with aryl groups (5,30,53,65), [Eq. (2)], and recently Wiberg (88,90) described a very mild route involving both [2 + 2] and [2 + 4] cycloreversions which occur at 60°C to generate Me2Si=C(SiMe3)2. However, the generality of this latter source of silenes has not been established yet [Eq. (3)]. 

Thus, the oxidation potential of the former type of diene (limonene) is substantially the same as that of the corresponding monoolefin (1-Me-cyclohexene), whereas norbor-nadiene and bicyclo[2.2.2]octadiene show much lower oxidation potentials than those of norbornene and cyclohexene. 

The reaction can be carried out intramolecularly to produce, in one step, three new rings in moderate yield (Equation (36)).149 It is noteworthy that up to six stereogenic centers could be formed. Additionally, cobalt-catalyzed [4 + 2 + 2]-cycloadditions of bicyclo[2.2.2]octadienes have been reported (Equations (37) and (38)).150... 

V.P. Conticello, D.L. Gin, and R.H. Grubbs, Ring-opening metathesis polymerization of substituted bicyclo[2.2.2]octadienes a new precursor route to poly(p-phenylene vinylene), J. Am. Chem. Soc., 114 9708-9710, 1992. 

The increase in ring size from the norbomadiene-type to bicyclo[2.2.2]octadiene systems appears not to affect the overall reaction outcome. Again the interaction involves... 

Eine Moglichkeit der Synthese einfacher Vierringverbindungen aus Cyclooctatetraenderivaten beruht auf der thermischen Spaltung der Dienaddukte vom Typ (XVIII) nach Alder-Rickert. Bei Anwendung dieser Methode erhielten Cope und Mitarbeiter (57) aus dem Addukt von Cyclooctatrien-I.3.5 bzw. Bicyclo(4.2.0)octadien-2.4 und Acetylen-dicarbonsauredimethylester (XVIII X=H) in vorzuglicher Ausbeute... 

One case of some interest for which kinetic data are not available, but for which equilibrium data are, is that of cyclo-octa-l,3,5-triene. At 100° there is a rapid equilibration between the triene and bicyclo[4,2,0] octadiene ... 

The remarkable tricyolo-octanes shown below have recently been synthesized (Avram et al., 1964). They both yield 1,5-cyclo-octadiene on pyrolysis at 150° C which suggests that the Mnetic parameters for these isomerizations cannot be two dissimilar to those for the isomerization of bicyclo[2,2,0]hexane,... 

Bicyclo[4,2,0]octene isomerizes smoothly to yield 1,3-cyclo-octadiene only at temperatures appreciably higher than are necessary for the mono-cyclic cyclobutenes. A study of this reaction in the gas phase in the temperature range 235 to 285° C yielded the Arrhenius equation... 

The asymmetric [3 + 4] cycloaddition is readily achieved using chiral auxiliaries or catalysts [16]. The efficiency of the chiral auxiliary approach is illustrated in the [3-1-4] cycloaddition with cyclopentadiene. The vinyldiazoacetate 6, with (T)-pantolactone as the chiral auxiliary, generated the bicyclo[3.2.1]octadiene 75 in 87% yield and 76% dia-stereomeric excess (Eq. 10) [82]. Alternatively, the chiral rhodium prolinate Rh2(S-DOSP)4-catalyzed reaction of 4 generated the bicyclo[3.2.1]octadiene 76 in 77% yield and with 93% enantiomeric excess (Eq. 11) [83]. 

New P-substituted benzo- and naphthofuryl derivatives of o-divinylbenzene were synthesized and irradiated in order to form annulated bicyclo[3.2.1]octadienes. The mechanism of the intramolecular (2+2]-cycloaddition was explained <99H(51)1355>. 

This equilibrium was first studied by Cope et a .54 in 1952. The Gibbs energy difference is small and the rate of interconversion slow at room temperature. Huisgen et al.55 examined the influence of variations of the ethane fragment on the position of the equilibrium. Attachment of a tricarbonyliron moiety apparently causes stabilization of the bicyclo[4.2.0]octadiene system,56 whereas with tricarbonylmolybdenum the monocyclic isomer is isolated as its metal complex.57... 

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