ISSN:
0894-3230
Keywords:
Organic Chemistry
;
Physical Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
Ab initio STO-3G and 6-31G minimized geometries of 5-oxo- (9), 6-oxo-7-oxabicyclo[2.2.1]hept-2-yl cation (12) and 7-oxabicyclo[2.2.1]hept-2-yl cation (15) were obtained. The energy barriers for their Wagner-Meerwein rearrangements to the more stable 5-oxo- (11), 6-oxo-3-oxabicyclo[2.2.1]hept-2-yl (13) and 3-oxabicyclo[2.2.1]hept-2-yl (17) cations, respectively, have been evaluated and compared with those calculated for the rearrangement of the 5-oxo (18) and 6-oxobicyclo[2.2.1]hept-2-yl cations (20). In agreement with experimental data, the ‘true migratory aptitude’ of an acyl group is higher than that of β-oxoalkyl group in competitive Wagner-Meerwein rearrangments that are ‘energetically unbiased’. The ease of the acyl group 1,2-shift toward an electron-deficient center is related to the electron-donating ability of the carbonyl group due to favorable n(CO) ↔ σ σ ↔ p(C+) hyperconjugative interaction.
Additional Material:
1 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/poc.610010507
