Azatriquinanes: Synthesis, Structure, and Reactivity
作者:Nicholas M. Hext、Jens Hansen、Alexander J. Blake、David E. Hibbs、Michael B. Hursthouse、Oleg V. Shishkin、Mark Mascal
DOI:10.1021/jo980788s
日期:1998.8.1
Azatriquinane, a tricyclic amine with rigid, hemispherical topology, is synthesized in six steps from pyrrole. This first example of a [2.2.2]cyclazine can be oxidatively dimerized to a novel, highly strained heptacycle or oxidized with chlorine to give an azatriquinacene, a theoretical precursor to diazadodecahedrane via Woodward dimerization.
Azatriquinane (=10-azatricyclo[5.2.1.0(1.10)]decane; 1) was oxidized to its radical cation 1(.+) by gamma-irradiation in a CF2ClCFCl2 matrix at 77 K. A prominent feature of the ESR spectrum of 1(.+) is the N-14-hyperfine anisotropy which broadens the components with M-1(N-14) = +/-1. The observed coupling constants are a(N)=+ 2.5 and a(H) =+ 4.0 mT for the N-14 nucleus and the three methine a-protons, respectively. While the a, value points to pyramidalization at the N-atom comparable to that in the radical cation of quinuclidine (=1-azabicyclo[2.2.2]octane; 4), an eclipsing of the singly occupied orbital at this atom by the three C-HB bonds is indicated in view of the large a(H) value. Theoretical calculations on the geometry of 1(.+) are in accord with the conclusions drawn from the experimental findings.