Issue 9, 1976

Conformational behaviour of medium-sized rings. Part III. Heterocyclic analogues of 12,13-dihydro-11H-dibenzo[a,e]cyclononene, 6,11,12,13-tetrahydro-5H-dibenzo[a,e]cyclononene, and 5,6,7,12,13,14-hexahydrodibenzo[a,f]cyclodecene

Abstract

The temperature dependence of the 1H n.m.r. spectra of a number of heterocyclic analogues (3a–c) of 12,13-dihydro-11H-dibenzo[a,e]cyclononene has been interpreted in terms of the interconversion of chair- and boat-like conformations. Conformational analysis on these molecules has been carried out with the aid of strain energy calculations on the thia-analogue (3c); in this case a useful correlation between calculated and experimental activation parameters was found. Variable temperature 1H n.m.r. spectroscopy and strain energy calculations have demonstrated that the heterocyclic analogues (4a–f) and (5a–d) of 6,11,12,13-tetrahydro-5H-dibenzo[a,f]-cyclononene and 5,6,7,12,13,14-hexahydrodibenzo[a,f]cyclodecene, respectively, all adopt flexible chair-like conformations with C2 symmetry which undergo an inversion process involving torsion about single bonds.

Article information

Article type
Paper

J. Chem. Soc., Perkin Trans. 1, 1976, 926-937

Conformational behaviour of medium-sized rings. Part III. Heterocyclic analogues of 12,13-dihydro-11H-dibenzo[a,e]cyclononene, 6,11,12,13-tetrahydro-5H-dibenzo[a,e]cyclononene, and 5,6,7,12,13,14-hexahydrodibenzo[a,f]cyclodecene

W. D. Ollis and J. F. Stoddart, J. Chem. Soc., Perkin Trans. 1, 1976, 926 DOI: 10.1039/P19760000926

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