Syntheses, X-ray structures and conformational studies of tetraoxa[n.n]metacyclophanes

Abstract

New types of macrocyclic ligands with tetraoxa[n.n]metacyclophane molecular skeletons have been synthesized. The structures of 14,28-dibromo-1,8,15,22-tetraoxa[8.8]metacyclophane 2a, 16,32-dibromo-1,10,17,26-tetraoxa[10.10]metacyclophane 2b, 14,28-dibromo-2,7,16,21-tetraoxa[8.8]metacyclophane 3a, 16,32-dibromo-2,9,18,25-tetraoxa[10.10]metacyclophane 3c, 18,36-dibromo-2,11,20,29-tetraoxa[12.12]metacyclophane 3d, 20,40-dibromo-2,13,22,33-tetraoxa[14.14]metacyclophane 3e and 14,28-diiodo- 2,7,16,21-tetraoxa[8.8]metacyclophane 9a have been determined by single-crystal X-ray structure analyses. In compounds 2a and 2b, two bromide atoms face each other within the macrocyclic ring while in compounds 3c, 3d and 3e the bromine atoms face in opposite directions, outwards from the macrocyclic ring. In the smaller ring compounds 3a and 9a the structure was intermediate between these two types.

Substitution of the bromine atoms via lithiation has been achieved smoothly with iodine and methyl iodide as the electrophiles to afford disubstituted compounds in good yields, while with trimethylsilyl chloride as the electrophile the mono-substituted compound has been obtained.

References

1. For recent papers concerning steric protections see; K. Toyota, H. Takahashi, K. Shimura and M. Yoshifuji, Bull. Chem. Soc. Jpn., 1996, 69, 141; F. Luderer, H. Reinke and H. Oehme, Chem. Ber., 1996, 129, 15; N. Tokitoh, H. Suzuki and R. Okazaki, Chem. Commun., 1996, 125.
2. As a representative paper see; T. Nabeshima, H. Furusawa and Y. Yano, Angew. Chem., Int. Ed. Engl., 1994, 33, 1750.
3. (a) T. Shinmyozu, T. Hirakawa, G. Wen, S. Osada, H. Takemura, K. Sako and J. M. Rudzinski, Liebigs Ann., 1996, 205; (b) Y. Fukazawa, Y. Yang, T. Hayashibara and S. Usui, Tetrahedron, 1996, 52, 2847; (c) T. Ishi-i, T. Sawada, S. Mataka, M. Tashiro and T. Thiamin, Chem. Ber., 1996, 129, 289; (d) V. V. Cane, W. H. De Wolf and F. Bickelhaupt, Tetrahedron, 1994, 50, 4575 and references therein.
4. M. Mascal, J.-L. Kerdelhue, A. S. Batsanov and M. J. Begley, J. Chem. Soc., Perkin Trans. 1, 1996, 1141.
5. Y. Delaviz, J. S. Merola, M. A. G. Berg and H. W. Gibson, J. Org. Chem., 1995, 60, 516.
6. Molecular mechanics and molecular dynamics calculations were performed using Chem 3D for Macintosh from Cambridge Scientific Computing Inc., Cambridge, MA.
7. M. J. S. Dewar, E. G. Zoebisch, E. F. Healy and J. J. P. Stewart, J. Am. Chem. Soc., 1985, 107, 3902; MOPAC ver. 6, J. J. P. Stewart, QCPE Bull., 1989, 9, 10; Revised as 6.01 for CONVEX C3440 by CONVEX Co.
8. A. Bondi, J. Phys. Chem., 1964, 68, 441; L. Pauling, The Nature of the Chemical Bond, 3rd edn. Cornell University Press, Ithaca, N. Y., 1961.
9. T. L. Davis and V. F. Harrington, J. Am. Chem. Soc., 1934, 56, 129.
10. A. Lüttringhaus, Liebigs Ann. Chem., 1937, 528, 181.
11. A. Lüttringhaus and K. Ziegler, Liebigs Ann. Chem., 1937, 528, 155.
12. Structure solution methods: PHASE; J. C. Calbrese, PHASE: Patterson Heavy Atom Solution Extractor, Ph. D. Thesis, University of Wisconsin-Madison, 1972; DIRDIF; P. T. Beurskens, DIRDIF: Direct Method for Difference Structures—an automatic procedure for phase extension and refinement of difference structure factors, Technical Report 1984/1 Crystallography Laboratory, Toernooiveld, 6525 Ed Nijmegen, Netherlands.
13. D. T. Cromer and J. T. Waber, International Tables for X-ray Crystallography, vol. IV, The Kynoch Press, Birmingham, England, 1974, Table 2.2A.
14. J. A. Ibers and W. C. Hamilton, Acta Crystallogr., 1964, 17, 781.
15. D. T. Cromer and J. T. Waber, International Tables for X-ray Crystallography, vol. IV, The Kynoch Press, Birmingham, England, 1974, Table 2.3.1.
16. TEXSAN—TEXRAY Structure Analysis Package, Molecular Structure Corporation, 1985.
17. K. K. Johnson, ORTEP II. Report ORNL-5138, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 1976.