87424-91-7Relevant academic research and scientific papers
Crystal Structures and Photoelectron Spectra of Some Trimethanoanthracenes, Tetramethanonaphthacenes, and Pentamethanopentacenes. Experimental Evidence for Laticyclic Hyperconjugation
Paddon-Row, Michael N.,Englehardt, Lutz M.,Skelton, Brian W.,White, Allan H.,Joergensen, Flemming S.,Patney, Harish K.
, p. 1835 - 1850 (2007/10/02)
Photoelectron (p.e.) spectra of the series of dienes (4), (10), (11a)-(13a), and crystal structures for the dodecachlorodienes (11b)-(13b) are reported.The spectra revealed large ?-splitting energies of 0.32 and 0.52 eV for (4) and (11a) respectively.The value of (4) is attributed to the presence of orbital interactions through six ? bonds (OIT-6-B), and this, taken with the p.e. data for the dienes (1)-(3), provides convincing evidence for the long-range nature of OIT-n-B.The larger ?-splitting energy of 0.52 eV observed for (11a), compared with (4), has been explained in terms of the presence of two reinforcing orbital interactions: OIT-6-B and a new variant of hyperconjugation, called laticyclic hyperconjugation, in which the ? MOs of the double bonds mix the (Ψ)? MO of the central CH2 bridge of (11a).The surprisingly large ?-splitting energy of 0.29 eV observed for (12a) is also due largely to laticyclic hyperconjugation involving both pairs of symmetry adapted(Ψ)? MOs of the CH2 bridges.No ?-splitting energy could be detected in the p.e. spectrum of (13a).From the crystal structures of (11b)-(13b), it was found that the distance between neighbouring CH2 groups, and between a double bond and its closest CH2 neighbour is about 3 Angstroem in all three compounds.HF/STO-3G calculations on model ethene...(CH4)n...ethene complexes suggest that laticyclic interactions, like OIT-n-B, are very long-range processes, the predicted ?-splitting energies amounting to ca. 10-3 eV for two double bonds separated by ca. 33 Angstroem.The relevance of these orbital interactions to biological electron-transfer processes is briefly discussed.
STEREOCHEMICAL FEATURES OF THE DIENE SYNTHESIS REACTION OF CYCLOPENTADIENE WITH DIENOPHILES OF THE NORBORNENE AND NORBORNADIENE SERIES
Kolesnikov, R. V.,Grigor'ev, A. A.,Vinberg, L. B.,Yampol'skii, Yu. Yu.,Zhavoronkov, I. P.
, p. 901 - 908 (2007/10/02)
The stereochemistry of the products from the reaction of cyclopentadiene with tetracyclo2,5.17,10>dodec-3-ene, endo- and exo-dicyclopentadiene, endo-dihydrodicyclopentadiene, bicyclohepta-2,5-diene, and endo,exo- and endo,endo-tetracyclo2,5.17,10>dodeca-3,8-diene was investigated.The presence, at the endo position of the dienophile, of a group which sterically hinders orientation of the cyclopentadiene with the methylene group in the trans position to the methylene group of the bicycloheptane system of the dienophile makes it possible for the corresponding exo,exo-dimethanonaphthalene derivatives to form.During the condensation of cyclopentadiene with bicyclohepta-2,5-diene the stable endo,endo adduct is formed in addition to the endo,exo structure.
Diels-Alder-Reactions. VIII. Kinetic Investigations of the Formation and the Pyrolysis of Tetracyclo3.6.02.7>dodec-4-en
Moll, K. K.,Ramhold, K.,Zimmermann, G.,Pohle, Ch.
, p. 1048 - 1052 (2007/10/02)
The formation of tetracyclo3.6.02.7>dodec-4-ene by codimerisation of cyclopentadiene with bicyclohept-2-ene between 60 and 140 deg C in the liquid phase and the inverse reaction by gas phase pyrolysis between 240 and 300 deg C were studied kinetically.The activation parameters were determined.
