Norbomadiene Norbornadiene

The Ni -catalysed (2+2) cycloaddition of activated olefins such as acrylonitrile or acrylic acid esters to quadricyclane which gives endo- and exo-substituted products is complicated particularly in the case of 1,2-disubstituted olefins by a competing isomerization of quadricyclane to norbornadiene. Norbomadiene gives identical cycloadducts under these conditions with a similar isomer ratio. Kinetic studies of the cycloaddition reactions of quadricyclane gave a plot of log [quadricyclane]t o/ [quadricyclane]i=t against time which exhibited a marked deviation from linearity due to the retarding effect of norbomadiene which is also formed and in turn coordinates to the Ni catalyst. Scheme 11 accounts for these observations. 

Y. Harel, A. W. Adamson, C. Kutal, P. A. Grutsch, K. Yasufuku. Photocalorimetry. 6. Enthalpies of Isomerization of Norbornadiene and of Substituted Norbomadienes to Corresponding Quadricyclenes. J. Phys. Chem. 1987, 91, 901-904. 

Butoxynorbomadiene provides a convenient route to 7-sub-stituted norbornenes and norbornadienes including anti-7-nor-bomenol,2 7-norbornadienyl acetate,2 7-norbornadienol,2 7-chloro-norbomadiene,8 7-methylnorbornadiene,8 and 7-phenylnorbor-... 

The polymer cobalt containing prophyrins (32), (33) were used in the photochemical energy storage system norbomadiene-quadricyclane (Eq. IS) This system for storage of solar energy is useful because of the high AH value between the two valence isomers on one side and the low price for the starting material (norbornadiene) on the other side. 

Diels-A Ider catalyst.1 The complex (1) catalyzes the homo-Diels-Alder condensation of vinyl compounds to norbomadiene. Thus the reaction of acrylonitrile with norbornadiene in the presence of this complex gives 8-cyanotetracyclo[4.3.0.02 .03-7]-nonane (2)2 as a mixture of epimers in 93 % yield. The yield of (2) using bis(triphenyl-phosphine)dicarbonylnickel(0) as catalyst is 86%. 

A stepwise sequence of nucleophilic addition to the complexed norbomadiene followed by intramolecular alkene insertion was first observed with dichloro(norbornadiene)palla-dium(II) which, upon addition of methanol, only forms the normal adduct 11. Subsequent conversion with l,2-bis(triphenylphosphanyl)ethane (dppe), however, gave the nortricyclene complex 12. Reductive displacement of the alkyl ligand with lithium aluminum hydride or oxidative cleavage with halogens gave noncomplexed nortricyclene derivatives. ... 

Investigations have also examined the photochemical outcome of the inclusion of other aromatic substituents onto the norbornadienes. Examples of this are the direct and sensitized irradiation of the naphthyl-substituted derivatives 249 that brings about cyclization to 250. Sensitization of the cyclization with ketones such as benzophenone leads to a much cleaner reaction. Biacetyl has also been used as the sensitizer . Cyclization also occurs with the norbomadiene 251 2. 

This photo-isomerization reaction is referred to as a valence isomerization. It is a reaction in which electron reshuffling occurs and the nuclei move to make or break new n and ct bonds. A number of polymers were, therefore, prepared with the norbomandiene moieties either in the backbone or as pendant groups. Among them are polyesters that were synthesized with donor-acceptor norbornadiene residues in the main chain [184] by polyaddition of 5-(4-methoxyphenyl)-l,4,6,7,7-pentamethyl-2,5-norbomadiene-2,3-dicarboxylic acid or 5,6-bis(4-methoxyphenyl)-7,7- dimethyl-2,5-norbomadiene-2. 

Nitroxyls s. N-Oxide radicals Norbomadiene s. Chromium tetracarbonyl-norbornadiene Norrish type I cleavage 20, 534s31... 

Sensitized isomerization of norbornadiene Valence isomerization of norbomadiene to quadricyclene has been suggested as a possible means of photochemical conversion and storage of solar energy. The isomerization of... 

Protonation of (norbornadiene)tricarbonyliron takes place at iron to give the hydride (47). Formation of a homoallylic intermediate (48) is not observed. However, it has now been found that the co-ordinated norbomadiene does undergo electrophilic substitution at carbon on treatment with dichloromethyl ether and titanium tetrachloride followed by hydrolysis to give (49). A homoallylic intermediate (50) is presumably involved. ... 

Norbornadienes Possessing Cationic Electron Withdrawing Groups Biphotochromic Norbomadiene Derivatives ... 

In order to study the influence of substituents on the geometry of the norbornadienyl moiety, x-ray structures of the compounds 63,64 have been investigated and compared with the literature data for the parent norbornadiene 1 and for 2-(2,2-diphenylvinyl)norbomadiene-3-carboxylic acid 65." ... 

Rosi, M., Sgamelotti, A., Francheschi, F., and Floriani, C., Use of norbomadiene in solar energy storage theoretical study of a copper(l) photosensitizer for the norbornadiene-quadricyclane transformation, fnorg. Chem., 38,1520-1522,1999. 

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