Oxidative rearrangement of pentaalkoxychalcones with phenyliodine(III) bis(trifluoroacetate) (PIFA): synthesis of (±)-10-bromopterocarpin and (±)-pterocarpin

Abstract

The oxidative rearrangement of pentaalkoxychalcones using the hypervalent iodine compound, phenyliodine(III) bis(trifluoroacetate) (PIFA), has been examined. Treatment of 2,2′-bis(benzyloxy)-4′-methoxy-4,5-methylenedioxychalcone with PIFA gives a rearrangement product in low yield, but 2,2′-bis(benzyloxy)-3-bromo-4′-methoxy-4,5-methylenedioxychalcone yields the rearrangement product, which leads to (±)-bromopterocarpin and (±)-pterocarpin.

References

1. W. Friedrichsen, in Comprehensive Heterocyclic Chemistry, ed. A. R. Katritzky and C. W. Rees, Pergamon, New York, 1984, vol. 4, p. 998.
2. T. A. Engler, K. O. Lynch Jr., J. P. Reddy and G. S. Gregory, Bioorg. Med. Chem. Lett., 1993, 3, 1229; T. A. Engler, W. Chai and K. O. LaTessa, J. Org. Chem., 1996, 61, 9297.
3. L. Farkas, À. Gottsegen and M. Nógrádi, J. Chem. Soc., Perkin Trans. 1, 1974, 305.
4. K. Thakkar and M. Cushman, J. Org. Chem., 1995, 60, 6499; T. Horie, K. Shibata, K. Yamashita, K. Fujii, M. Tsukayama and Y. Ohtsuru, Chem. Pharm. Bull., 1998, 46, 222.
5. R. A. Lichtenfels, A. L. Coelho and P. R. R. Costa, J. Chem. Soc., Perkin Trans. 1, 1995, 949.
6. R. M. Moriarty, J. S. Khosrowshahi and O. Prakash, Tetrahedron Lett., 1985, 26, 2961.
7. Y. Miki, S. Kobayashi, N. Ogawa and H. Hachiken, Synlett, 1994, 1001 and references cited therein.
8. J. A. Ferreira, J. W. Nel, E. V. Brandt, B. C. B. Bezuidenhoudt and D. Ferreira, J. Chem. Soc., Perkin Trans. 1, 1995, 1049.
9. T. H. Simpson and P. S. Wright, J. Org. Chem., 1961, 26, 4886.
10. The chalcone 2a was treated with TTN [Tl(NO₃)·3H₂O] in MeOH for 1 h to give the rearrangement product 3a in 83% yield. Treatment of the chalcone 2b with TTN in MeOH gave a complex mixture but in MeOH–CH(OMe)₃ for 20 h 2b yielded rearrangement product 3b in 46% yield.
11. Y. Ozaki, K. Mochida and S.-W. Kim, J. Chem. Soc., Chem. Commun., 1988, 374; T. A. Engler, J. P. Reddy, K. D. Combrink and D. V. Velde, J. Org. Chem., 1990, 55, 1248.
12. K. Mori and H. Kishida, Liebigs Ann. Chem., 1988, 721.
13. T. A. Engler, J. P. Reddy, K. D. Combrink and Q. V. Velde, J. Org. Chem., 1990, 55, 1254.
14. M. Uchiyama and M. Matsui, Agric. Biol. Chem., 1967, 31, 1490.