Bicyclic olefin

Ternary Pd-catalyzed coupling reactions of bicyclic olefins (most often norbor-nadiene is used) with aryl and vinyl halides and various nucleophiles have been investigated intensively over the past few years [44]. A new approach in this field is to combine Heck and Suzuki reactions using a mixture of phenyliodide, phenyl-boronic acid and the norbornadiene dicarboxylate. Optimizing the conditions led to 84% of the desired biphenylnorbornene dicarboxylate [45]. Substituted phenyl-iodides and phenylboronic acids can also be used, though the variation at the norbornadiene moiety is highly limited. 

P. C. Gravelle and S. J. Teichner Acid-Catalyzed Isomerization of Bicyclic Olefins... 

The spiroketone 28 was converted into its tosylhydrazone whose sodium salt 29 was heated without solvent in a high vacuum. The bicyclic olefin 30 was formed and being a cyclobutene, Woodward and Hoffmann allowed it to ring-open to afford 31 and these two products were collected in a trap cooled by liquid nitrogen. When the mixture was permitted to warm up, an exothermic reaction (again allowed by W H) set in and the cyclobuteno[4.2.2]propellane 32 was formed11. ... 

An alternative method for the preparation of polymer-chained pendant ligands has been recently developed.102 The polymerization of the (R)-hydroxylpiperidinyl fragment was realized by ROMP of a bicyclic olefin with the commercially available Grubbs catalyst. 

Unlike the oxymercuration of acyclic olefins, oxymercuration of bicyclic olefins often gives jy -addition products. Norbornenes 93, for example, show exclusive fvo-oxymercuration. In this reaction, the ratio between the isomers depends on the nature of the fvo-substituent (R1) and tro/o-substituent (R2) (Equation (36)). The presence of electron-withdrawing fvo-substituents always leads to a much greater selectivity in favor of 94a-d over 95a-d.116 117 As indicated by extensive theoretical calculations, the charge distribution in the transition states governs the selectivity of these reactions.118... 

There are so many different examples of photochemical dimerizations and cross-cycloadditions 8-11,13-17) 0f olefinic compounds that one is not surprised to find several variations of mechanistic patterns. Simple olefins, including dienes and strained small ring, bicyclic olefins and styrene derivatives form a class of compounds that undergo such reactions sensitized by triplet energy donors. Some examples axe given in Eqs. 19—23, where only cyclobutane products are depicted. Theory... 

Expecting that acidic isomerization involving a double Wagner-Meerwein rearrangement would transform the bicyclic olefin 74 into supposedly stable [10.10]betweena-nene and its (Z)[10.10] isomer, they treated 74 with H2S04-AcOH in benzene only to find that the product was an 85 15 mixture of 75 and 76. Solvolysis of the spiro compound 77 was also found to yield a 60 40 mixture of 75 and 76 which was totally free from the fused (Z)[10.10] and ( )[10.10] olefins. 

Indole derivatives might also be prepared by the palladium catalysed reductive heteroannulation of o-nitrostyrene derivatives. The bicyclic olefin, shown in 3.75. was converted to the indole derivative in good yield.94 The reaction, which was run under forcing conditions utilises carbon monoxide as the reducing agent. 

Jefford Gunsher Hill Brun Le Gras Waegell Org. Synth. VI, 142. For a review of the addition of halocarbenes to bridged bicyclic olefins see Jefford Chimin 1970, 24, 357-363. 

A similar conclusion can be drawn from the higher reactivity of 1,1-dialkylalkenes compared with 1,2-dialkylalkenes. Norbomene and related bicyclic olefins were... 

Alkenes participate readily in oxymercuration with increasing alkyl-substitution resulting in decreasing reactivity.489,491,492 The oxymercuration of alkenes is usually an anti process.493 195 Exceptions are strained bicyclic olefins, such as norbomene495,496 [Eq. (6.83)],497 and frans-cyclooctene and frans-cyclononene.494... 

It has been reported (102) that the equatorial bicyclic ketotosylate 360 (R=CH3) is transformed into monocyclic olefin ester 362 (R=CH3) by treatment with sodium ethoxide while the axial isomer 363 yielded the bicyclic olefin 364. Similarly, compound 360 (R=C00CH3) gave 362 (R=C00CH3 ) (103). Thus, reactions with the equatorial tosylates take place via the stereoelectroni-cally controlled fragmentation of intermediate 361 (R=CH3 or COOC2H5). 

Internal olefins react more slowly than terminal olefins, and mixtures of regio-isomers are usually formed. Accompanying olefin isomerization can further complicate product selectivity. Despite these words of warning, the reaction can still give satisfactory results (Table 4), for example in the final step of the total synthesis of annuionone A (29), which involves oxidation of bicyclic olefin 28 [49]. A... 

At the end of considerations dealing with the insertion polymerisation of norbornene one should mention the Pd-catalysed polymerisation of other bicyclic olefins such as exo-8,9-dihydrodicyclopentadiene (tricyclo[5.2.1.02,6]... 

In common with the polymerisation of acyclic olefins (oc-olefins) by Ziegler Natta catalysts, the ring-opening metathesis polymerisation of monocyclic and bicyclic olefins is promoted by alkylmetal-activated transition metal halides, and only a relatively small proportion of the transition metal atoms introduced into the system is converted into the active sites for the polymerisation. Also, as in the polymerisation of ethylene by Phillips catalysts, the metathesis polymer-... 

The above examples show that the ring-opening metathesis polymerisation of cycloolefins, even simple substituted bicyclic olefins, gives rise, in principle, to polymers with a very wide range of microstructures defined by the frequency and distribution of cis and trans vinylene units, m and r diads and h-h, t-t or h-t arrangements of cycloaliphatic units. 

Karlen, T., Ludi, A., Miihlebach, A., Bernhard, P. and Pharisa, C., Photoinduced Ringopening Metathesis Polymerisation of Strained Bicyclic Olefins with Ruthenium Complexes , J. Polym. Sci., A, Polym. Chem., 33, 1665-1674 (1995). 

The reaction starts probably by elimination of the tertiary fluorine atoms. Thus, a bicyclic olefin is formed. Its double bond activates the four allylic fluorines for nucleophilic displacement by thiophenoxide anions to give l,4,5,8-tetrakis(phenylthio)perfluoro-A9 10-octalin. 

A representative 1,3-dipolar cycloaddition process occurs with yV-aryl-C-(trifiuoromethyl)-nitrilimines, generated from the corresponding hydrazonoyl bromides, c.g. 4. under basic conditions. which can react with dimethyl fumarate and maleate,bicyclic olefins. and dipolarophiles containing cumulative double bonds. With sodium isocyanates as the dipolarophilc the cycloaddition reaction occurs across the C = N bond, while with potassium isothiocyanate it occurs through the C = S bond. ... 

The reaction of olefins with azides to prepare an aziridine is one of the simplest methods to prepare a type I aziridine. Unfortunately, this method has not found particularly general use. There are however substrates (particularly bicyclic olefins) for which these types of reactions work quite well. One example is shown in Equation (6) <2004SC3073>. Reaction of tricyclic olefin 23 with tosylazide provides aziridines 24a and 24b in excellent yield. 

Table 2. Allylic oxidation of bicyclic olefins 48-50 with selenium dioxide/formic acid...

Elimination of iodohydrias. Treatment of the iodohydrin (1) with freshly distilled phosphoryl chloride in pyridine first at 0° and then at room temperature (30 min.) affords the bicyclic olefin (2) in high yield. The reaction is generally applicable for olefin synthesis,... 

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