Cyclic alkynes–electronic behaviour as a function of ring strain

Abstract

UV/Vis spectroscopic analysis of a series of cross-conjugated enediyne macrocycles as a function of increasing ring strain and planarity shows little effect on the electronic absorptions of the macrocycles, despite an obvious rehybridization of the alkylidene carbon atoms as evidenced by ¹³C NMR spectroscopy.

References

1. Conjugated Polymers and Related Materials: The Interconnection of Chemical and Electronic Structure, ed. W. R. Salaneck, I. Lundström and B. Rånby, OUP, Oxford, 1993.
2. Y. Zhao and R. R. Tykwinski, J. Am. Chem. Soc., 1999, 121, 458.
3. Polydiacetylenes, ed. D. Bloor and R. R. Chance, Martinus Nijhoff, Dordrecht, 1985.
4. S. Eisler and R. R. Tykwinski, Angew. Chem., in the press.
5. W. Sander, Angew. Chem., Int. Ed. Engl., 1994, 33, 1455.
6. H. Meier, N. Hanold, T. Molz, H. J. Bissinger, H. Kolshorn and J. Zountsas, Tetrahedron, 1986, 42, 1711.
7. G. Maas and H. Hopf, in The Chemistry of Dienes and Polyenes, ed. Z. Rappoport, Wiley, Chichester, 1997, pp. 927–977.
8. A. Krebs and J. Wilke, Top. Curr. Chem., 1983, 109, 189.
9. R. Gleiter and W. Schäfer, in The Chemistry of Triple-Bonded Functional Groups: Supplement C2, ed. S. Patai, Wiley, Chichester, 1994, pp. 153–189.
10. R. Gleiter, Angew. Chem., Int. Ed. Engl., 1992, 31, 27.
11. R. Gleiter and R. Merger, in Modern Acetylene Chemistry, ed. P. J. Stang and F. Diederich, VCH, Weinheim, 1995, pp. 285–319.
12. J. Anthony, A. M. Boldi, C. Boudon, J.-P. Gisselbrecht, M. Gross, P. Seiler, C. B. Knobler and F. Diederich, Helv. Chim. Acta, 1995, 78, 797.
13. R. Faust, F. Diederich, V. Gramlich and P. Seiler, Chem. Eur. J., 1995, 1, 111.
14. M. Schreiber, R. R. Tykwinski, F. Diederich, R. Spreiter, U. Gubler, C. Bosshard, I. Poberaj, P. Günter, C. Boudon, J.-P. Gisselbrecht, M. Gross, U. Jonas and H. Ringsdorf, Adv. Mater., 1997, 9, 339.
15. H. Hopf, Angew. Chem., Int. Ed. Engl., 1984, 23, 948.
16. P. J. Stang and T. E. Fisk, Synthesis, 1979, 438–440.
17. L. Brandsma, Preparative Acetylenic Chemistry, Elsevier, Amsterdam, 1988.
18. A. S. Hay, J. Org. Chem., 1962, 27, 3320.
19. H. N. C. Wong and F. Sondheimer, Tetrahedron, 1981, 37, W99.
20. H. Hopf and G. Maas, Angew. Chem., Int. Ed. Engl., 1992, 31, 931.
21. A change in absorption energy as a result of angle deformation would also be expected for the in-plane π-system of the central butadiyne moiety of 8a-c, as has been previously shown for cycloalkynes (ref. 8). Whereas absorptions are observed in the expected region of the butadiyne segment (ca. 250–275 nm) of 8a-c, interpretation of shifts is, at this point, inconclusive. The expected absorption range of 250–275 nm is based on the lowest energy absorptions of known butadiyne derivatives, see: J. B. Armitage and M. C. Whiting, J. Chem. Soc., 1952, 2005 I thank one of the reviewers for helpful suggestions.