ISSN:
0018-019X
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
It is predicted by MINDO/3 calculations that the 1,5-trishomobarrelenediyl dication 4 would be as much stabilized over the bicyclo[2.2.2]octanediyl dication 3 as the monocation 7-H is energetically favored over the hypothetical 1-bicyclo[2.2.2]octyl 10-H. In spite of this, the bridgehead cations generated from the 1,5-dihalo-trishomobarrelenes 6-F, 6-Cl, 6-Br, and 6-I and from the 1,5-diol 6-OH under long-lived ion conditions were only the 5-substituted monocations 7-F, 7-Cl, 7-Br, 7-I, and 7-OH, respectively, unequivocally identified by their 1H- and 13C-NMR spectra as well as quenching products. Although there is efficient charge delocalization in 7-X, as revealed by the 13C-chemical shifts, the lack of formation of the bridgehead bridgehead dication 4 is not due to an unforeseen destabilization by the three α-annellated cyclopropyl groups. Even the 1,5-dichlorotetracyclo[3.3.2.02,4.06,8]decanes 17-Cl2 and 19-Cl2 and 1,5-dichlorotricyclo[3.2.2.02,4]nonane 12-Cl2 with only two and one α-cyclopropyl groups, respectively, gave the bridgehead monocations 18-Cl, 20-Cl, and 13-Cl, respectively.
Additional Material:
6 Tab.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/hlca.19850680505
Permalink
