15914-95-1Relevant articles and documents
Orbital Interactions. 6. The Birch Reduction as a Tool for Exploring Orbital Interactions through Bonds. Through-Three-Bond Interactions
Paddon-Row, Michael N.,Hartcher, Robert
, p. 662 - 670 (1980)
Product and relative rate data have been obtained for the Birch reduction (Li/liquid NH3/tert-butyl alcohol) of a number of 1,4-methanobiphenylenes.The rates of reduction of the double bond in exo- and endo-1,4,4a,8b-tetrahydro-1,4-methanobiphenylene (exo- and endo-16) are respectively 141 and 78 times greater than the rate of reduction of norbornene.However, the reduction of the aromatic rings in exo- and endo-16 showed little enhancement compared with the rates of reduction of exo- and endo-1,2,3,4,4a,8b-hexahydro-1,4-methanobiphenylenes (exo- and endo-19), respectively.The double bonds of exo- and endo-1,4,4a,5,8,8b-hexahydro-1,4-methanobiphenylenes (exo- and endo-18) are little affected compared with norbornene.Interactions between the vacant MOs in these and other molecules were explored with the aid of extended Hueckel calculations.The results of these calculations demonstrated the presence of sizable through-bond interactions in exo-16.However, net through-space interactions in the vacant MO manifold are predicted to prevail in endo-16.A causal connection between the presence of orbital interactions and the rates of Birch reductions of exo and endo compounds 16, 18, and 19 was established within the framework of the mechanism of the reaction.A linear relationship between ln (rate of reduction) of a substrate and its LUMO energy was observed.
Effect of Dihydroaromatic Compounds on the Cation Radical Chain Oxygenation of Tetraalkyl Olefins
Nelsen, Stephen F.,Teasley, Mark F.
, p. 3474 - 3479 (1986)
Ionic chain hydrogenation of syn-sesquinorbornene (7) to 13 by 1,4-cyclohexadiene (11) may be initiated by tris(2,4-dibromophenyl)aminium (9.+) hexachloroantimonate at -78 deg C and is efficient enough to inhibit cation radical catalyzed oxygenation of 7 by oxygen.The chain-carrying steps appear not to involve radicals, and the reaction can be initiated by HBF4 at low temperature or TFA at above room temperature. anti-Sesquinorbornene (8) is considerably less reactive and requires HBF4 to initiate hydrogenation.Isopropylideneadamantane (16) requires FSO3H for initiation, but biadamantylidene (1) is not hydrogenated under our conditions.Nevertheless, addition of 5 equiv of 11 intercepts the kinetic chain for cation radical catalyzed oxygenation of 1 to dioxetane 2; the chain length for consumption of 1 drops from over 800 to less than 2, and epoxide 19 becomes a major product.It is proposed that the open peroxy carbocation B.+ is trapped by 11 to lead to the observed results.
SYNTHESIS OF anti-SESQUINORBORNENE AND RELATED POLYCYCLIC ALKENES via REDUCTIVE ELIMINATION OF VICINAL DICYANO DERIVATIVES
Lucchi, Ottorino De,Piccolrovazzi, Nicoletta,Licini, Giulia,Modena, Giorgio,Valle, Giovanni
, p. 401 - 408 (2007/10/02)
A methodology for the preparation of both endocyclic unsaturated molecules via reductive elimination of vicinal dicyano derivatives is reported.The method is useful for the preparation of anti-sesquinorbornene and related hitherto unknown molecules starting from the respective vicinal dicyano derivatives which are readily available via Diels-Alder reactions.From a practical point of view, the best decyanation procedure for these substrates is to use finely dispersed sodium in tetrahydrofuran under sonication.The X-ray analysis of anti-1,4,4a,5,8,8a-hexahydro-1,4;5,8-dimethanonaphthalene-4a,8a-dicarbonitrile, 3, is reported.Crystal data: orthorhombic, space group P212121; Z=4; a=16.059(5), b=8.920(3), c=7.592(3) Angstroem; V=1087.5 Angstroem3, Dc=1.27 g*cm-3.
