Highly regioselective nucleophilic/cycloaddition reactions of N-arylamino 1,3-diazabuta-1,3-dienes with α-nitrosostyrenes: synthesis of functionalised imidazoles and imidazole oxides

Abstract

The α-nitrosostyrenes 2, generated in situ from α-halogeno oximes, underwent regioselective cycloadditon/nucleophilic reactions with N-arylamino 1,3-diazabuta-1,3-dienes 1 leading to a mixture of imidazoles and cyclic nitrones shown to have structures 3 and 4, respectively, by X-ray crystallographic analysis. The structure 4 for cyclic nitrones was also supported by their 1,3-dipolar cycloaddition with dimethyl acetylenedicarboxylate (DMAD). The thermolysis of nitrones 4 gives imidazoles 3 via oxadiazine intermediates 6.

References

1. For reviews on nitrosodienophiles, see (a) D. L. Boger, Tetrahedron, 1983, 39, 2869; (b) S. M. Weinreb, in Comprehensive Organic Synthesis, eds. B. M. Trost, I. Fleming and L. A. Paquette, Pergamon Press, New York, 1991, pp. 401–512; (c) H. Waldman, Synthesis, 1994, 535; (d) H. Waldman, Organic Synthesis highlights II, VCH Publishing, New York, 1995, pp. 37–47; (e) P. Zuman and B. Shah, Chem. Rev., 1994, 94, 1621.
2. For reviews on acyl nitroso species, see: (a) G. W. Kirby, Chem. Soc. Rev., 1977, 1; (b) P. F. Vogt and M. J. Miller, Tetrahedron, 1998, 54, 1317.
3. (a) T. L. Gilchrist, Chem. Soc. Rev., 1983, 12, 53; (b) E. J. T. Crystal, T. L. Gilchrist and W. Stretch, J. Chem. Res. (S), 1987, 180; (M), 1563 and the references therein.
4. R. Zimmer and H. U. Reissig, Angew. Chem., Int. Ed., Engl., 1988, 27, 1518.
5. R. Faragher and T. L. Gilchrist, J. Chem. Soc., Chem. Commun., 1976, 581.
6. A. K. Sharma and M. P. Mahajan, Heterocycles, 1995, 40, 787.
7. (a) E. C. K. Lai, D. Mackay, N. J. Taylor and K. N. Watson, J. Chem. Soc., Perkin Trans. 1, 1990, 1497; (b) D. Mackay and K. N. Watson, J. Chem. Soc., Chem. Commun., 1982, 775; 777.
8. (a) A. K. Sharma, S. N. Mazumdar and M. P. Mahajan, J. Chem. Soc., Perkin Trans. 1, 1997, 3065; (b) A. K. Sharma, S. N. Mazumdar and M. P. Mahajan, Tetrahedron Lett., 1993, 34, 7961.
9. (a) P. D. Dey, A. K. Sharma, S. N. Rai and M. P. Mahajan, Tetrahedron, 1995, 51, 7459; (b) P. D. Dey, A. K. Sharma, P. V. Bharatam and M. P. Mahajan, Tetrahedron, 1997, 53, 13829.
10. J. H. Smith, J. H. Heidema and E. T. Kaiser, J. Am. Chem. Soc., 1972, 94, 9276.
11. S. Nakanishi, J. Nantaku and Y. Otsuji, Chem. Lett., 1983, 341.
12. G. M. Sheldrick, SHELXTL-PC-A Program for Calculation of Crystal Structures, 1995, Siemens Analytical Instruments Inc., Wisconsin, USA.