J . Org. Chem. 2000, 65, 8807-8810
8807
Notes
Sch em e 1
An Efficien t Keton e-Ca ta lyzed Ep oxid a tion
Usin g Hyd r ogen P er oxid e a s Oxid a n t
Lianhe Shu and Yian Shi*
Department of Chemistry, Colorado State University,
Fort Collins, Colorado 80523
yian@lamar.colostate.edu
Received August 3, 2000
Epoxides are very important building blocks in organic
synthesis.1 Dioxiranes, either isolated or generated in
situ, have been shown to be extremely versatile epoxi-
dation reagents.2-6 In nearly every case, the generation
of dioxiranes uses potassium peroxomonosulfate (KHSO5)
as oxidant (Scheme 1).7,8 During our recent study on
asymmetric epoxidation using the fructose-derived ketone
(1), we found that hydrogen peroxide (H2O2) could be used
as primary oxidant in combination with acetonitrile (eq
1).6l High yields and ee’s were obtained for a number of
efficiency of the epoxidation reactions. Higher pH is
usually beneficial to both the conversion and ee’s.6b-c
A
similar phenomenon was also observed in the asymmetric
epoxidation when H2O2 was used as the oxidant.6l In
current studies, the pH effect was further investigated
using trifluoroacetone (CF3COCH3) and tetrahydropyran-
4-one as catalyst. The reaction was run in a 1:1 mixture
of CH3CN and aqueous EDTA solution (4 × 10-4 M) using
trans-â-methylstyrene as substrate. The reaction pH was
(4) For examples of in situ generation of dioxiranes, see: (a)
Edwards, J . O.; Pater, R. H.; Curci, R.; Di Furia, F. Photochem.
Photobiol. 1979, 30, 63. (b) Curci, R.; Fiorentino, M.; Troisi, L.;
Edwards, J . O.; Pater, R. H. J . Org. Chem. 1980, 45, 4758. (c) Gallopo,
A. R.; Edwards J . O. J . Org. Chem. 1981, 46, 1684. (d) Cicala, G.; Curci,
R.; Fiorentino, M.; Laricchiuta, O. J . Org. Chem. 1982, 47, 2670. (e)
Corey, P. F.; Ward, F. E. J . Org. Chem. 1986, 51, 1925. (f) Adam, W.;
Hadjiarapoglou, L.; Smerz, A. Chem. Ber. 1991, 124, 227. (g) Kurihara,
M.; Ito, S.; Tsutsumi, N.; Miyata, N. Tetrahedron Lett. 1994, 35, 1577.
(h) Denmark, S. E.; Forbes, D. C.; Hays, D. S.; DePue, J . S.; Wilde, R.
G. J . Org. Chem. 1995, 60, 1391 (i) Yang, D.; Wong, M. K.; Yip, Y. C.
J . Org. Chem. 1995, 60, 3887. (j) Denmark, S. E.; Wu, Z.; Crudden, C.
M.; Matsuhashi, H. J . Org. Chem. 1997, 62, 8288. (k) Denmark, S. E.;
Wu, Z. J . Org. Chem. 1997, 62, 8964. (l) Boehlow, T. R.; Buxton, P. C.;
Grocock, E. L.; Marples, B. A.; Waddington, V. L. Tetrahedron Lett.
1998, 39, 1839. (m) Denmark, S. E.; Wu, Z. J . Org. Chem. 1998, 63,
2810. (n) Frohn, M.; Wang, Z.-X.; Shi, Y. J . Org. Chem. 1998, 63, 6425.
(o) Yang, D.; Yip, Y.-C.; J iao, G.-S.; Wong, M.-K. J . Org. Chem. 1998,
63, 8952. (p) Yang, D.; Yip, Y.-C.; Tang, M.-W.; Wong, M.-K.; Cheung,
K.-K. J . Org. Chem. 1998, 63, 9888.
(5) For leading references on asymmetric epoxidation mediated in
situ by chiral ketones, see: (a) Curci, R.; Fiorentino, M.; Serio, M. R.
J . Chem. Soc., Chem. Commun. 1984, 155. (b) Curci, R.; D’Accolti, L.;
Fiorentino, M.; Rosa, A. Tetrahedron Lett. 1995, 36, 5831. (c) Reference
4h. (d) Brown, D. S.; Marples, B. A.; Smith, P.; Walton, L Tetrahedron
1995, 51, 3587. (e) Yang, D.; Yip, Y. C.; Tang, M. W.; Wong, M. K.;
Zheng, J . H.; Cheung, K. K. J . Am. Chem. Soc. 1996, 118, 491. (f) Yang,
D.; Wang, X.-C.; Wong, M.-K.; Yip, Y.-C.; Tang, M.-W. J . Am. Chem.
Soc. 1996, 118, 11311. (g) Song, C. E.; Kim, Y. H.; Lee, K. C.; Lee, S.
G.; J in, B. W. Tetrahedron: Asymmetry 1997, 8, 2921. (h) Adam, W.;
Zhao, C.-G. Tetrahedron: Asymmetry 1997, 8, 3995. (i) Denmark, S.
E.; Wu, Z.; Crudden, C. M.; Matsuhashi, H. J . Org. Chem. 1997, 62,
8288. (j) Wang, Z.-X.; Shi, Y. J . Org. Chem. 1997, 62, 8622. (k)
Armstrong, A.; Hayter, B. R. Chem. Commun. 1998, 621. (l) Yang, D.;
Wong, M.-K.; Yip, Y.-C.; Wang, X-C.; Tang, M.-W.; Zheng, J .-H.;
Cheung, K.-K. J . Am. Chem. Soc. 1998, 120, 5943. (m) Yang, D.; Yip,
Y.-C.; Chen, J .; Cheung, K.-K. J . Am. Chem. Soc. 1998, 120, 7659. (n)
Adam, W.; Saha-Moller, C. R.; Zhao, C.-G. Tetrahedron: Asymmetry
1999, 10, 2749. (o) Wang, Z.-X.; Miller, S. M.; Anderson, O. P.; Shi, Y.
J . Org. Chem. 1999, 64, 6443. (p) Carnell, A. J .; J ohnstone, R. A. W.;
Parsy, C. C.; Sanderson, W. R. Tetrahedron Lett. 1999, 40, 8029. (q)
Armstrong, A.; Hayter, B. R. Tetrahedron 1999, 55, 11119.
olefins. In this epoxidation, peroxyimidic acid 2 is likely
to be the active oxidant for the formation of the dioxirane
(eq 2).9,10 The epoxidation requires substantially less
solvent and salts compared to the procedure using Oxone,
along with being operationally simple. To further extend
this oxidant system (H2O2-CH3CN) to the dioxirane-
mediated epoxidation, we have tested a variety of achiral
ketones as possible catalysts. Among those tested, tri-
fluoroacetone (CF3COCH3) was found to be a particularly
active catalyst. Herein we wish to report our recent
studies in this area.
In our previous studies of the asymmetric epoxidations
with Oxone as oxidant, it has been found that the pH of
reaction mixture is a very important factor to the
* To whom correspondence should be addressed. Phone: 970-491-
7424. Fax: 970-491-1801.
(1) For reviews, see: (a) Gorzynski Smith, J . Synthesis 1984, 629.
(b) Besse, P.; Veschambre, H. Tetrahedron 1994, 50, 8885.
(2) For general leading references on dioxiranes, see: (a) Murray,
R. W. Chem. Rev. 1989, 89, 1187. (b) Adam, W.; Curci, R.; Edwards, J .
O. Acc. Chem. Res. 1989, 22, 205. (c) Curci, R.; Dinoi, A.; Rubino, M.
F. Pure & Appl. Chem. 1995, 67, 811. (d) Clennan, E. L. Trends Org.
Chem. 1995, 5, 231. (e) Adam, W.; Smerz, A. K. Bull. Soc. Chim. Belg.
1996, 105, 581. (f) Denmark, S. E.; Wu, Z. Synlett 1999, 847.
(3) Murray, R. W.; Singh, S. Org. Synth. 1996, 74, 91.
10.1021/jo001180y CCC: $19.00 © 2000 American Chemical Society
Published on Web 11/14/2000