E. Krawczyk et al. / Tetrahedron: Asymmetry 15 (2004) 2599–2602
2601
Chem. 1992, 57, 4320; (c) Brandes, B. D.; Jacobsen, E. N.
Tetrahedron Lett. 1995, 36, 5123; (d) Brandes, B. D.;
Jacobsen, E. N. J. Org. Chem. 1994, 59, 4378; (e) Fukuda,
T.; Irie, R.; Katsuki, T. Synlett 1995, 197; (f) Sakaki, H.;
Irie, R.; Katsuki, T. Synlett 1993, 300; (g) Hosoya, N.;
Hatayama, A.; Ianai, K.; Fujii, H.; Irie, R.; Katsuki, T.
Synlett 1993, 641.
O
O
OP(OPh)2
OP(OEt)2
Ph
Ph
O
O
R1
R1
Mn
Mn
7. (a) Fukuda, T.; Katsuki, T. Tetrahedron Lett. 1996, 37,
4389; (b) Adam, W.; Fell, R. T.; Mock-Knoblauch, C.;
Saha-Moller, C. R. Tetrahedron Lett. 1996, 37, 6531.
(R,R)-cat.
(R,R)-cat.
´
8. Koprowski, M.; Krawczyk, E.; Skowronska, A.; McPart-
lin, M.; Choi, N.; Radojevic, S. Tetrahedron 2001, 57,
O
O
(S)
Ph
(R)
Ph
R1
R1
1105.
9. Adam, W.; Hadjiarapoglou, L.; Jager, V.; Klicic, J.;
OH
´
OH
Seidel, B.; Wang, X. Chem. Ber. 1991, 124, 2361.
´
Figure 2.
10. Skowronska, A.; Koprowski, M.; Krawczyk, E. Phospho-
rus, Sulfur Silicon 2002, 177, 1877.
11. Zhang, W.; Loebach, J. L.; Wilson, S. R.; Jacobsen, E. N.
J. Am. Chem. Soc. 1990, 112, 2801.
In summary, we have shown that really easily available
(E)-enol phosphates can be stereoselectively epoxidized
and than converted into a-hydroxy ketones with high
enantioselectivity up to 96% by (salen) Mn(III) Jacob-
senÕs complex. Our results demonstrate that absolute
configuration of a-hydroxy ketones was controlled by
the steric bulk and electronic factors of the phosphate
group in enol phosphates. The synthetic scope of (salen)
Mn(III)-catalyzed asymmetric epoxidation is extended
by conversion of (E)-enol phosphates into the pool of
successful substrates.
12. Enol phosphates 2a–h were prepared from the corre-
sponding ketones by the action of dialkylphosphoro-
chloridate, according to reported procedure: Hayashi, T.;
Fujiwa, T.; Okamoto, Y.; Katsuro, Y.; Kumada, M.
Synthesis 1981, 1001.
13. (a) Deng, L.; Jacobsen, E. N. J. Org. Chem. 1992, 57,
4320; (b) Pospisil, P. J.; Carsten, D. H.; Jacobsen, E. N.
Chem. Eur. J. 1996, 2, 974; (c) Finney, N. S.; Pospisil, P.
J.; Chang, S.; Palucki, M.; Konsler, R. G.; Hansen, K. B.;
Jacobsen, E. N. Angew. Chem., Int. Ed. 1997, 36, 1720.
14. General procedure for epoxidation: To a stirred solution
of NaOCl (4mL, 7equiv) and phosphate buffer (4mL,
pH = 11) the mixture of appropriate enol phosphate
(1.1mmol, 1equiv), 4-phenylpyridine N-oxide (PPNO)
(30mol%), and (salen) Mn(III) complex 1 (7mol%) in
4mL CH2Cl2 was added at 10°C temperature. The stirring
of the reaction mixture was continued at 0°C for 18h (the
reaction was monitored by TLC), n-hexane (40mL) was
added, organic layer was separated, washed with distilled
water and dried (MgSO4). Evaporation of solvent afforded
crude epoxide, which was diluted with Et2O and treated
with CF3COOH in H2O (10mL) at 0°C. Stirring was
continued until TLC analysis revealed the complete
consumption of epoxide. Then the mixture was washed
with NaHCO3, CHCl3 was added, the organic layer was
separated, washed with water, and dried. After removal of
the solvent, the residue was subjected to silica gel column
chromatography with hexane–ethyl acetate (3:1 v/v) as
the eluent, to afford pure, optically active a-hydroxy
ketones 4.
Acknowledgements
This work was supported by the State Committee for
Scientific Research, Poland (No 7T09A 148 21).
References
1. (a) Hanessian, S. Total Synthesis of Natural products: The
Chiron Approach; Pergamon: New York, 1983; Chapter 2;
(b) Whitesell, J. K.; Buchanan, C. M. J. Org. Chem. 1986,
51, 5443; (c) Du Bois, J.; Tomooka, C. S.; Hong, J.;
Carreira, E. M. Acc. Chem. Res. 1997, 30, 364.
2. Coppola, G. M.; Schuster, H. F. a-Hydroxy Acids in
Enantioselective Synthesis; Wiley-VCH: Weinheim, 1997.
3. (a) Davis, F. A.; Chen, B.-C. Chem. Rev. 1992, 92, 919; (b)
Hashiyama, T.; Morikawa, K.; Sharpless, K. B. J. Org.
Chem. 1992, 57, 5067; (c) Knight, R. L.; Leeper, F. J. J.
Chem. Soc., Perkin Trans. 1 1998, 1891; (d) Enders, D.;
Breuer, K.; Teles, J. Helv. Chim. Acta 1996, 79, 1217; (e)
Enders, D.; Breuer, K. In Comprehensive Asymmetric
Catalysis; Jacobsen, E. N., Pfaltz, A., Yamamoto, H.,
Eds.; Springer: Berlin, 1999; Vol. 2, pp 1093–1102; (f)
Koike, T.; Murata, K.; Ikariya, T. Org. Lett. 2000, 2,
3833; (g) Lee, J. C.; Jin, Y. S.; Choi, J. H. Chem. Commun.
2001, 956.
4. (a) Adam, W.; Diaz, M. T.; Fell, R. T.; Saha-Moller, C. R.
Tetrahedron: Asymmetry 1996, 7, 2207; (b) Kawai, Y.;
Hida, K.; Tsujimoto, M.; Kondo, S.; Kitano, K.; Naka-
mura, K.; Ohno, A. Bull. Chem. Soc. Jpn. 1999, 72, 99.
5. (a) Adam, W.; Fell, R. T.; Stegmann, V. R.; Saha-Moller,
C. R. J. Am. Chem. Soc. 1998, 120, 708; (b) Zhu, Y.; Tu,
Y.; Yu, H.; Shi, Y. Tetrahedron Lett. 1998, 39, 7819; (c)
Adam, W.; Fell, R. T.; Saha-Moller, C. R.; Zhao, C.-G.
Tetrahedron: Asymmetry 1998, 9, 4117.
15. a-Hydroxy ketones 4a–g gave satisfactory spectroscopic
characterization. 4h (3-Hydroxy-2,3-dihydro-1H-phenan-
thren-4-one): Yellow oil; Rf = 0.58 (petrol-EtOAc, 1:1
20
v/v); ½a ¼ þ17:5 (c 0.4, CHCl3); mmax/cmꢁ1 (film): 3454
D
(br w, OH), 2962 (s, C–H), 1663 (s, C@O), 1602 (m, C@C),
1460 (m, C@C); dH (200MHz, CDCl3): 2.16 (ddd, J = 4.8,
12.8, 17.5Hz, 1H, CH2), 2.61 (dd, J = 5.8, 6.1Hz, 1H,
CH2), 3.20 (dd, J = 4.0, 17.5Hz, 1H, CH2), 3.99 (ddd,
J = 4.3, 13, 17.3Hz, 1H, CH2), 4.48 (dd, J = 5.0, 13.6Hz,
1H, CH–OH), 4.31 (br s, 1H, OH), 7.31 (d, J = 8.4Hz, 1H,
ArH), 7.53 (t, J = 7.4Hz, 1H, ArH), 7.66 (dd, J = 7.4,
8.1Hz, 1H, ArH), 7.83 (d, J = 8.1Hz, 1H, ArH), 7.97 (d,
J = 8.4Hz, 1H, ArH), 9.35 (d, J = 8.6Hz, 1H, ArH); dC
(50.33MHz, CDCl3): 22.084(CH ), 32.240 (CH2), 73.781
2
(CHOH), 124.805 (ArC), 125.842 (ArC), 126.241 (ArC),
126.744 (ArC), 128.365 (ArC), 129.120 (ArC), 132.491
(ArCIV), 135.038 (ArCIV), 146.444 (ArCIV), 148.321
(ArCIV), 201.571 (C@O); m/z (CI, isobutene): 213
([M++H], 100%); HRMS: Calcd for C14H13O2
(C14H12O2 + H+) 213.09155. Found 213.09102.
6. (a) Lee, N. H.; Muci, A. R.; Jacobsen, E. N. Tetrahedron
Lett. 1991, 32, 5055; (b) Deng, L.; Jacobsen, E. N. J. Org.