Conformational behaviour of medium-sized rings. Part 7. 5,6,7,12-tetrahydrodibenzo[a, d]cyclo-octene

Farouk Eltayeb Elhadi; W. David Ollis; J. Fraser Stoddart

doi:10.1039/P19780001415

Conformational behaviour of medium-sized rings. Part 7. 5,6,7,12-tetrahydrodibenzo[a, d]cyclo-octene

Farouk Eltayeb Elhadi, W. David Ollis^*, J. Fraser Stoddart

^*Corresponding author for this work

Chemistry

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Abstract

The temperature dependences of the ¹H n.m.r. and broad-band decoupled ¹³C n.m.r. spectra of 5.6.7.12-tetrahydrodibenzo[a, d]cyclo-octene (4) have been interpreted in terms of the interconversion of chair- and boat-like conformations. Strain energy calculations on selected conformations of this hydrocarbon (4) have led to useful correlations between calculated and experimental thermodynamic parameters.

Original language	English (US)
Pages (from-to)	1415-1421
Number of pages	7
Journal	Journal of the Chemical Society, Perkin Transactions 1
DOIs	https://doi.org/10.1039/P19780001415
State	Published - 1978

Funding

Perkin I interactional strain (Enb)between hydrogen atoms on C-6 and C-12. Thus, although calculations on cis,cis-cyclo- octa-l,4-diene and its dibenzo-analogue (4)predict the same conformational type for the more stable ground 5 Boa) TSlA (0 o -+-+I (lob1 TSlA* (0o +-+-I (10d) TSlBX (-+O 0-+) (llb) TSZ*(+-+-oo) state of both eight-membered ring compounds, they lead to quite different conclusions regarding the con-formational nature of the less stable ground state. This is not surprising in view of our findings l5 for 7,12- dihydro-5H-dibenzo[c,f]thiocin (13) and 5,6,7,12-tetra- hydro-6-me thyldibenz [c,f] azocine (14) where strain (13) X =S (15)X = Nh' energy calculations indicate (i) a minimum energy Boat for the thiocin derivative (13)which lies fairly close to a TB conformation, and (ii) little energy difference between the various Boat conformations that lie on the pathway TB B TB* +B* for the azocine derivative (14). In addition, a crystal structure analysis 1978 1421 has shown 23 that 5,6,7,12-tetrahydro-6-t-butyldibenz-tetrahydrodibenzocyclo-octene (4), and its heterocyclic [c,f]azocine (15) adopts a Boat conformation midway analogues [e.g. (13)-(15)]. between B and TB type conformations. Clearly, the situation is a finely balanced one in relation to the myriad We thank Dr. B. F. Taylor most warmly for his col-of flexible Boat conformations available to the eight- laboration in recording the 13C n.m.r. spectra. We grate- membered rings of cis,cis-cyclo-octa-l,4-diene,the fully acknowledge financial support (to F. E. E.) from the British Council. 23 A. D. Hardy and F. R. Ahmed, Acta Cryst., 1974, B30,1674. [7/1693 Received, 26th September, 19771

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@article{643047a29d5e4b299ea02ba88b016dfa,

title = "Conformational behaviour of medium-sized rings. Part 7. 5,6,7,12-tetrahydrodibenzo[a, d]cyclo-octene",

abstract = "The temperature dependences of the 1H n.m.r. and broad-band decoupled 13C n.m.r. spectra of 5.6.7.12-tetrahydrodibenzo[a, d]cyclo-octene (4) have been interpreted in terms of the interconversion of chair- and boat-like conformations. Strain energy calculations on selected conformations of this hydrocarbon (4) have led to useful correlations between calculated and experimental thermodynamic parameters.",

author = "Elhadi, {Farouk Eltayeb} and Ollis, {W. David} and Stoddart, {J. Fraser}",

note = "Funding Information: Perkin I interactional strain (Enb)between hydrogen atoms on C-6 and C-12. Thus, although calculations on cis,cis-cyclo- octa-l,4-diene and its dibenzo-analogue (4)predict the same conformational type for the more stable ground 5 Boa) TSlA (0 o -+-+I (lob1 TSlA* (0o +-+-I (10d) TSlBX (-+O 0-+) (llb) TSZ*(+-+-oo) state of both eight-membered ring compounds, they lead to quite different conclusions regarding the con-formational nature of the less stable ground state. This is not surprising in view of our findings l5 for 7,12- dihydro-5H-dibenzo[c,f]thiocin (13) and 5,6,7,12-tetra- hydro-6-me thyldibenz [c,f] azocine (14) where strain (13) X =S (15)X = Nh' energy calculations indicate (i) a minimum energy Boat for the thiocin derivative (13)which lies fairly close to a TB conformation, and (ii) little energy difference between the various Boat conformations that lie on the pathway TB B TB* +B* for the azocine derivative (14). In addition, a crystal structure analysis 1978 1421 has shown 23 that 5,6,7,12-tetrahydro-6-t-butyldibenz-tetrahydrodibenzocyclo-octene (4), and its heterocyclic [c,f]azocine (15) adopts a Boat conformation midway analogues [e.g. (13)-(15)]. between B and TB type conformations. Clearly, the situation is a finely balanced one in relation to the myriad We thank Dr. B. F. Taylor most warmly for his col-of flexible Boat conformations available to the eight- laboration in recording the 13C n.m.r. spectra. We grate- membered rings of cis,cis-cyclo-octa-l,4-diene,the fully acknowledge financial support (to F. E. E.) from the British Council. 23 A. D. Hardy and F. R. Ahmed, Acta Cryst., 1974, B30,1674. [7/1693 Received, 26th September, 19771",

year = "1978",

doi = "10.1039/P19780001415",

language = "English (US)",

pages = "1415--1421",

journal = "Journal of the Chemical Society, Perkin Transactions 1",

issn = "1470-4358",

publisher = "Chemical Society",

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T1 - Conformational behaviour of medium-sized rings. Part 7. 5,6,7,12-tetrahydrodibenzo[a, d]cyclo-octene

AU - Elhadi, Farouk Eltayeb

AU - Ollis, W. David

AU - Stoddart, J. Fraser

N1 - Funding Information: Perkin I interactional strain (Enb)between hydrogen atoms on C-6 and C-12. Thus, although calculations on cis,cis-cyclo- octa-l,4-diene and its dibenzo-analogue (4)predict the same conformational type for the more stable ground 5 Boa) TSlA (0 o -+-+I (lob1 TSlA* (0o +-+-I (10d) TSlBX (-+O 0-+) (llb) TSZ*(+-+-oo) state of both eight-membered ring compounds, they lead to quite different conclusions regarding the con-formational nature of the less stable ground state. This is not surprising in view of our findings l5 for 7,12- dihydro-5H-dibenzo[c,f]thiocin (13) and 5,6,7,12-tetra- hydro-6-me thyldibenz [c,f] azocine (14) where strain (13) X =S (15)X = Nh' energy calculations indicate (i) a minimum energy Boat for the thiocin derivative (13)which lies fairly close to a TB conformation, and (ii) little energy difference between the various Boat conformations that lie on the pathway TB B TB* +B* for the azocine derivative (14). In addition, a crystal structure analysis 1978 1421 has shown 23 that 5,6,7,12-tetrahydro-6-t-butyldibenz-tetrahydrodibenzocyclo-octene (4), and its heterocyclic [c,f]azocine (15) adopts a Boat conformation midway analogues [e.g. (13)-(15)]. between B and TB type conformations. Clearly, the situation is a finely balanced one in relation to the myriad We thank Dr. B. F. Taylor most warmly for his col-of flexible Boat conformations available to the eight- laboration in recording the 13C n.m.r. spectra. We grate- membered rings of cis,cis-cyclo-octa-l,4-diene,the fully acknowledge financial support (to F. E. E.) from the British Council. 23 A. D. Hardy and F. R. Ahmed, Acta Cryst., 1974, B30,1674. [7/1693 Received, 26th September, 19771

PY - 1978

Y1 - 1978

N2 - The temperature dependences of the 1H n.m.r. and broad-band decoupled 13C n.m.r. spectra of 5.6.7.12-tetrahydrodibenzo[a, d]cyclo-octene (4) have been interpreted in terms of the interconversion of chair- and boat-like conformations. Strain energy calculations on selected conformations of this hydrocarbon (4) have led to useful correlations between calculated and experimental thermodynamic parameters.

AB - The temperature dependences of the 1H n.m.r. and broad-band decoupled 13C n.m.r. spectra of 5.6.7.12-tetrahydrodibenzo[a, d]cyclo-octene (4) have been interpreted in terms of the interconversion of chair- and boat-like conformations. Strain energy calculations on selected conformations of this hydrocarbon (4) have led to useful correlations between calculated and experimental thermodynamic parameters.

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JF - Journal of the Chemical Society, Perkin Transactions 1

ER -

Conformational behaviour of medium-sized rings. Part 7. 5,6,7,12-tetrahydrodibenzo[a, d]cyclo-octene

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