The electron resonance spectra of I and II in their ionized forms are similar to that of bis(2,2,6,6-tetramethylpiperidin-4-ol) glutarate (IV) at 23°( Figure 1). In the un-ionized forms the widths of the second and fourth lines have decreased and the spectra resemble that of IV at 46°. The observation of five equally spaced spectral lines shows that the spin exchange, J, is much greater than the nitrogen coupling constant, a,
homoadamantene (111) the double bond is part of two seven-membered rings; I11 should be less strained l 6 than adamantene in which the double bond is part of two six-membered rings. Perhaps 111 can be compared in its expected behavior with l-bicyclo[3.2.2]nonene (IX) which dimerizes slowly (half-life about 25 min at Oo).l7 The strain energies of these bridgehead olefins await experimental determination or accurate molecular mechanics calculation.Hofmann degradation of N,N,N-trimethyl-3-homoadamantylammonium hydroxide, expected to give rise to 3-homoadamantene (111) or its 2-isomer, gave a mixture of at least three C22H,2 dimers,I8 which showed identical laser Raman spectra and glc retention times with dimers C, D, and E.Current investigations in this laboratory show that the carbene ring enlargement method is general for the synthesis of other bridgehead olefins in bridged systems.
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