H-1 NMR study has shown that long-lived 9-R-9,10-dimethylphenanthren-9-yl cations (R = isopropenyl, trans-1-methylprop-1-en-1-yl) generated in the system HSO3F-SO2ClF-CD2Cl2 at -130 degrees C undergo degenerate rearrangement via 1,2-vinyl shifts (Delta G(not equal) = 37 and 39 kJ/mol, respectively, at -88 degrees C). Analysis of the geometric parameters of the initial structures and transition states calculated by the DFT method indicates that unfavorable steric factors are responsible for the sharp deceleration of 1,2-shifts of the isopropenyl and trans-1-methylprop-1-en-1-yl groups as compared to vinyl and cis-1-methylprop-1-en-1-yl groups, respectively.
H-1 NMR study has shown that long-lived 9-R-9,10-dimethylphenanthren-9-yl cations (R = isopropenyl, trans-1-methylprop-1-en-1-yl) generated in the system HSO3F-SO2ClF-CD2Cl2 at -130 degrees C undergo degenerate rearrangement via 1,2-vinyl shifts (Delta G(not equal) = 37 and 39 kJ/mol, respectively, at -88 degrees C). Analysis of the geometric parameters of the initial structures and transition states calculated by the DFT method indicates that unfavorable steric factors are responsible for the sharp deceleration of 1,2-shifts of the isopropenyl and trans-1-methylprop-1-en-1-yl groups as compared to vinyl and cis-1-methylprop-1-en-1-yl groups, respectively.
Degenerate rearrangements of long-lived 9,10-dimethyl-9-(1-methyl-1-vinyl)-phenanthrenium and 9,10-dimethyl-9-(trans-1-methyl-1-propenyl)phenanthrenium ions: unexpected strong retardation of vinyl migrations
作者:Vitaly G. Artamoshkin、Vladimir A. Bushmelev、Alexander M. Genaev、Vyacheslav G. Shubin
DOI:10.1070/mc2006v016n02abeh002209
日期:2006.1
As found by dynamic NMR, the rates of degenerate rearrangements of long-lived 9,10-dimethyl-9-(1-methyl-1-vinyl)phenanthrenium and 9, 10-dimethyl-9-(trans-1-methyl-1-propenyl)phenanthrenium ions proceeding by 1,2-vinyl shifts are unexpectedly much lower than those of the 9,10-dimethyl-9-vinylphenanthrenium and 9,10-dimethyl-9-(cis-1-methyl-1-propenyl)phenanthrenium ions.
Degenerate rearrangement of 9-isopropenyl-9,10-dimethyl-phenanthren-9-yl and 9,10-dimethyl-9-(trans-1-methylprop-1-en-1-yl)phenanthren-9-yl cations
作者:V. G. Artamoshkin、V. A. Bushmelev、A. M. Genaev、V. G. Shubin
DOI:10.1134/s1070428006090016
日期:2006.9
H-1 NMR study has shown that long-lived 9-R-9,10-dimethylphenanthren-9-yl cations (R = isopropenyl, trans-1-methylprop-1-en-1-yl) generated in the system HSO3F-SO2ClF-CD2Cl2 at -130 degrees C undergo degenerate rearrangement via 1,2-vinyl shifts (Delta G(not equal) = 37 and 39 kJ/mol, respectively, at -88 degrees C). Analysis of the geometric parameters of the initial structures and transition states calculated by the DFT method indicates that unfavorable steric factors are responsible for the sharp deceleration of 1,2-shifts of the isopropenyl and trans-1-methylprop-1-en-1-yl groups as compared to vinyl and cis-1-methylprop-1-en-1-yl groups, respectively.