Bicyclo octyl

Both 1-adamantyl bromide and l-bromobicyclo[2,2,2]octane react rapidly with trimethylaluminium, even at — 70 °C, to give good yields of the bridgehead methyl derivatives 1-bromonorbomane is inert under these conditions. Likewise, coupling of the 1-adamantyl and 1-bicyclo-octyl bromides with MeMgBr gave satisfactory yields of the methyl derivatives, whereas 1-bromonorbornane did not react. It has been... 

The interest in the nature of alkyl substituent effects continues. A comparison of Up and Up values obtained from p-bicyclo[2,2,2]octan-l -yl- and p-adamantan-1-yl-benzoic acids and the corresponding 2-chloropropanes shows these alkyl groups are capable of greater electron release than methyl or t-butyl (ffp for bicyclo-octyl, 0.25 adamantyl, 0.24 methyl, 0.17 and t-butyl, 0.20),... 

When bicyclo[2.2.2]octyl brosylate was solvolyzed in acetic acid containing sodium acetate, the products were a mixture of bicyclo[2.2.2]octyl acetate and bicyclo[3.2.1]octyl acetate, each of which was optically active. The formation of bicyclo[2.2.2]octyl acetate was found to proceed with 82 15% retention of configuration, a result which is in... 

Scheme 2.12 Intramolecular TMM [3+2 cycloaddition to bicyclo[3.3.0 octyl systems...

The activation energies for the fragmentation of the carbene in CH2C12 were calculated by the B3LYP/6-31G method to be 14.6, 2.2, and —0.95 for the bicyclo[2.2.1]heptyl, bicyclo[2.2.2]octyl, and adamantyl systems, respectively. Are the product trends consistent with these computational results, which presumably reflect the relative stability of the carbocation formed by the fragmentation ... 

Dimalone [bicyclo-(2.2.1)-5-heptene-2,3-dicarboxylic acid dimethyl ester] and Octa-cide 264 [the V-octyl imide of bicyclo-(2.2.1)-5-heptene-2,3-dicarboxylic acid] do produce a red color with an absorption maximum in the same region as that obtained in the analysis of Compound 118. However, because Dimalone is an insect repellent and Octacide 264 is a pyrethrum synergist, neither of these products is likely to be encountered in commercial mixtures of Compound 118. The response to the colorimetric test for Compound 118 of some chemicals commonly used for insect control is listed in Table V. 

The predominantly syn stereochemistry of the products arising from the bicyclo[3.2.1] octyl cation IV would results from the large ring strain in II, the chair conformation of which, (but not boat) facilitate the Wagner-Meerwein type rearrangement. 

Symmetric bicycloalkyl groups. An example is the l-bicyclo[2.2.2]octyl group. Symmetric trigonal bipyramidal groups of the type MZ4. No common examples are known, the only known example is PF4. 

The charge photoseparation in porphyrin-quinone compounds with a rigid bicyclo[2.2.2]octyl bridge, ensuring a distance between the centres of P and Q of about 16 A, has been studied [57]. The rate constant of intramolecular electron transfer from P to Q was found to depend on the dielectric properties of the medium and reached 3.3 x 107s 1 for a solution of P-L-Q in propionitrile. 

To determine the parameters of electron tunneling from P to Q, the kinetics of P fluorescence decay was studied for P-Lr-Q compounds where the rigid bridge was made up of one or two bicyclo[2.2.2]octyl fragments [58,... 

Fig. 10. Structure of porphyrin-quinone compounds with a rigid bicyclo[2.2.2]octyl bridge.

At T = 77 K in MTHF, the kinetics of fluorescence decay of P-L-Q with a bridge containing one bicyclo[2.2.2]octyl is of a non-exponential character. This effect can be explained by the coexistence in the frozen solution of several rotational conformations of the P-L-Q molecule (rotation of the porphyrin fragment around the a bond in its meso position is meant here). The characteristic time of the fluorescence decay for the predominant portion of the P-L-Q particles at 77 K, r 1.1 x 10 1°s, virtually coincides with the value of r = l/k(e1 at 298 K, i.e. the rate of tunneling from P to Q is independent of temperature. The exponential character of the fluorescence decay curve at 298 K indicates that, at this temperature, the rate of rotation exceeds k(e1. ... 

Since evo-2-norbornyl arenesulfonates apparently do solvolyze with anchi-meric assistance, the less strained 2-bicyclo[2.2.2]octyl derivatives (92) are of interest. In this system no comparison of the. rates of exo and endo derivatives can be made, since a substituent exo to one bridge is endo to t fief other. Stereochemical studies are, however, possible. If the carbonium ion (93) were formed from chiral 92 by participation of the —C6 bond, it would be chiral. Scheme 5 shows that attack at C2 of 93 should give retained bicyclo[2.2.2.]octyl solvolysis products (92a), and attack at Cx should give chiral exo-2-bicyclo[3.2.1]octyl... 

Two laboratories, those of Walborsky and of Goering, simultaneously investigated the stereochemistry of solvolysis of optically active bicyclo[2.2.2]-octyl arenesulfonates, and both found that the product consists of only two compounds 2-bicyclo[2.2.2]octyl and exo-2-bicyclo[3.2.1] derivatives.The [2.2.2] system is largely retained although there is some attendant racemization, and the [3.2.1] system is also chiral but again partially racemized. Both groups concluded that ionization at C2 is assisted by the —C6 bond ajH that flip product... 

Adcock, Shiner and coworkers found a significant 48.6-fold rate enhancement for the 4-trimethylsilyl bicyclo[2.2.2]octyl mesylate 265 compared with the silicon-free analogue 266102. The effects of trimethylgermyl and trimethyltin groups in the 4-position (in 267... 

Bridgehead bicyclo[4.4.0]decyl, bicyclo[4.3.0]nonyl, and bicyclo[3.3.0]octyl cations are found to be rapid equilibrating ions (see Section 3.5.2.1).188 The isomeric bridgehead congressane (diamantane) cations 52 and 53 have been prepared and observed.182 The diamant-4-yl cation 52 rapidly rearranges to the diamant-l-yl cation 53 at —60°C, possibly through intermolecular hydride shifts. Bridgehead bicyclo[3.3.3]undec-l-yl cation 54 has also been observed by 1H and 13C NMR spectroscopy.189... 

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