Akademik Veri Yönetim Sistemi
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, sa.6, ss.1111-1117, 2003 (SCI-Expanded)
The origin of double bond pyramidalization in the series of norbornene and norbornadiene derivatives and the effect of heteroatoms on the magnitude of the double bond bending are reported. For this purpose, equilibrium geometries, vibrational frequencies, and NBO second-order perturbation energies were calculated by use of B3LYP/6-31G** level wave functions. The optimized geometric parameters calculated for norbornadiene are in good agreement with the available experimental results. NBO second-order perturbation analysis has been used to evaluate the effect of hyperconjugative interactions on double bond pyramidalization. In the second part of this study, the interaction of singlet oxygen with 4,5-dioxatetracyclo[6.6.1.0(2,7).0(9,14)]pentadeca- 2(7),9,11,13 -tetra-ene (15) and 4,5,15-trioxatetracyclo[6.6.1.0(2,7).0(9,14)]pentadeca-2(7),9,11,13-tetraene (16) has been studied at the B3LYP/6-31G** level. In the case of addition of singlet oxygen to 15, 4,5,16-trioxapentacyclo[6.6.1.1(2.7).0(2,7).0(9,14)]- hexadeca-9,11,13-triene (17) is produced. It was found that the reaction of singlet oxygen addition to the double bond in 16 does not occur. The degree of pyramidalization in this molecule is similar to the analog 12 {4,5,11-trioxatricyclo[6.2. 1.0(2,7)]undeca-2(7),9-diene}, in which singlet oxygen addition takes place. The reasons of the lack of chemical reactivity with singlet oxygen in 16 are discussed.