Steric acceleration in the reaction of aryl bromides with tributylstannyl radicals

Abstract

Approximate absolute rate constants for the abstraction of bromine from a series of aryl bromides by stannyl radicals have been determined: 2,4,6-tri-tert-butylbromobenzene and 2,4,6-triphenylbromobenzene are found to be unusually reactive, most likely owing to steric acceleration.

References

1. G. A. Russell, in Free Radicals, ed. J. K. Kochi, Wiley, New York, 1973, vol. 1, pp. 275–331.
2. B. Giese, Angew, Chem., Int. Ed. Engl., 1983, 22, 753.
3. J. M. Tedder and J. C. Walton, Tetrahedron, 1980, 36, 701.
4. J. M. Tedder, Angew. Chem., Int. Ed. Engl., 1982, 21, 401.
5. R. P. Allen, B. P. Roberts and C. R. Willis, J. Chem. Soc., Chem. Commun., 1989, 1387.
6. D. P. Curran, C. P. Jasperse and M. J. Totleben, J. Org. Chem., 1991, 56, 7169.
7. M. Newcomb, Tetrahedron, 1993, 49, 1151.
8. J. Graham and J. R. Quayle, J. Chem. Soc., 1955, 3814.
9. A. Haaland, K. Rypdal, H. P. Verne, W. Scherer and W. R. Thiel, Angew. Chem., Int. Ed. Engl., 1994, 33, 2443.
10. W. R. Dolbier, Chem. Rev., 1996, 96, 1557.
11. P. A. Brady and J. Carnduff, J. Chem. Soc., Chem. Commun., 1974, 816.
12. C. H. Ruchardt, Top. Curr. Chem., 1980, 88, 1.