6239-90-3Relevant academic research and scientific papers
Rearrangements of 6-Tricyclo2,7>octyl Cations. Factors Influencing the Relative Stabilities of Bridged Carbocations
Bentley, T. William,Goer, Bernhard,Kirmse, Wolfgang
, p. 3066 - 3073 (2007/10/02)
The objective of this work was to explore the effect of ring strain on ? delocalization of carbocations.The 6-tricyclo2,7>octyl cation (3) incorporates 2-norbornyl and 2-bicyclohexyl structures in a highly strained molecular framework.Solvolyses of the epimeric brosylates 22 and 23, as well as nitrous acid deaminations of the analogues amines, 24 and 21, served to generate 3.The exo:endo rate ratios of the brosylates and the exo:endo product ratios of the tricyclo2,7>octan-6-ols (19, 20) are close to unity.Product distributions and kinetic data suggest a weak ka contribution at least for the endo brosylate 23.Several nondegenerate rearrangements of 3 were elucidated: Migration of C-2 from C-7 to C-6 (3 28) is followed, in part, by fragmentation (28 31).A minor fraction of 3 undergoes 4,6-hydride shifts (3 37 38).The degeneracy of 3 was probed with the aid of a 6-2H label.Migration of C-8 from C-7 to C-6 was found to be rapid, as compared to nucleophilic capture, whereas the norbornyl-type Wagner-Meerwein rearrangement (migration of C-4) was not observed.Product and label distributions indicate that the bridged structure (involving C-6, -7, and -8) 3c is nearly isoenergetic ( 0.5 kcal/mol) with the unsymmetrical ion 3a while products from the norbornyl-type delocalized ion (3b) are not observed, so 3b must be less stable by at least 3 kcal/mol.The exceptional order of the relative stabilities is explained in terms of "olefinic strain", i.e., the additional strain resulting from contraction of the basal bond in bridged carbocations.
Rearrangements of Tricyclo3.6>octyl Systems
Sauers, Ronald R.,Weston, Charles A.,Dentz, Bernard I.
, p. 2813 - 2816 (2007/10/02)
New 2,2-substituted derivatives of tricyclo3.6>octane with the following sets of substituents were synthesized in a study designed to test their stability toward Wagner-Meerwein rearrangements: CH3, OH; CH3, Cl; C6H5, OH; Cl, Cl; Br, CO2H.Epimerizations, but not skeletal rearrangements, were observed in some cases.The phenyl carbinol underwent self-reduction under vigorous conditions.
