Table 4 Alkene epoxidation catalysed by complex (R)-2 using PhIO
e.e.a (%)
Benzene
25 ЊC b
Toluene
25b
Substrate
Product
0c
Ϫ20 ЊC d
Styrene
4-Chlorostyrene
cis-β-Methylstyrene
Styrene oxidee, f
38 (82)
38 (91)
64 (70)
34 (68)
36 (65)
63 (59)
42 (62)
43 (63)
71 (67)
46 (68)
46 (64)
76 (63)
4-Chlorostyrene oxidee,g
cis-β-Methylstyrene oxideh
a
Based on amount of PhI formed; yields (%) in parentheses. b Reaction for 0.5–1 h. c Reaction for 1–1.5 h. d Reaction for 3 h. e R configuration.
f Benzaldehyde (2%) was detected after each run. g 4-Chlorobenzaldehyde (trace, except toluene, 25 ЊC: 4%) was detected after each run. h 1R, 2S
Configuration. trans-β-Methylstyrene oxide (benzene: 6%; toluene, 25 ЊC: 7%; 0 ЊC and Ϫ20 ЊC: trace) was detected after each run.
3 C. Rosini, L. Franzini, A. Raffaelli and P. Salvadori, Synthesis, 1992,
504; R. Noyori, Chem. Soc. Rev., 1989, 18, 187; R. Noyori and
H. Takaya, Acc. Chem. Res., 1990, 23, 345 and refs. therein.
4 C. W. Ho, W. C. Cheng, M. C. Cheng, S. M. Peng, K. F. Cheng and
C. M. Che, J. Chem. Soc., Dalton Trans., 1996, 405.
5 K. Bernardo, S. Lippard, A. Robert, G. Commenges, F. Dahan and
B. Meunier, Inorg. Chem., 1996, 35, 387.
isolation has so far been unsuccessful, the active species in this
system remains a point of contention.
Unlike the manganese() catalysts, epoxidation of alkenes
was not observed using the iron() complex (R)-4. Addition of
PhIO to a solution of (R)-4 led to rapid decomposition of the
metal species.
6 M. N. Bhattacharjee, M. K. Chaudhuri and D. T. Khathing,
J. Chem. Soc., Dalton Trans., 1982, 669.
Conclusion
7 D. D. Perrin, W. L. F. Armarego and D. R. Perrin, Purification of
Laboratory Chemicals, 2nd, edn., Pergamon, Oxford, 1980.
8 H. Lindler and R. Dubuis, Org. Synth., 1973, Coll. Vol. V, 880.
9 L. F. Fieser and M. Fieser, Reagents for Organic Synthesis, Wiley,
New York, 1967, vol. 1, p. 137.
10 PATTY and DIRDIF 92, P. T. Beurskens, G. Admiraal,
G. Beurskens, W. P. Bosman, S. Garcia-Granda, R. O. Gould,
J. M. M. Smits and C. Smykalla, The DIRDIF program system,
Technical Report of the Crystallography Laboratory, University of
Nijmegen, 1992.
11 NRCVAX, E. J. Cabe, Y. Le Page, J. P. Charland, F. L. Lee and
P. S. White, J. Appl. Crystallogr., 1989, 22, 384.
12 SIR 92, A. Altomare, M. Cascarano, C. Giacovazzo, A. Guagliardi,
M. C. Burla, G. Polidori and M. Camalli, J. Appl. Crystallogr., 1994,
27, 435.
New monomeric chiral binaphthyl Schiff-base complexes of
manganese and iron have been prepared using acetonitrile as
solvent. The manganese() derivatives (R)-1 to 3 mediate the
catalytic asymmetric epoxidation of alkenes by PhIO and the
highest e.e. in this system so far has been achieved at Ϫ20 ЊC in
low-polarity toluene. In contrast to the planar structures
observed for Jacobsen-type catalysts,18 the crystal structures of
the racemic complexes 3ؒCH2Cl2 and 4ؒ2H2O depict non-planar
molecules. This fundamental difference may be responsible for
the higher e.e. obtained by Jacobsen, since in our system the
environment for metal–alkene interaction is evidently more
open, and this may ultimately lead to different reaction
patterns.
13 TEXSAN, Crystal Structure Analysis Package, Molecular
Corporation, Houston, TX, 1985 and 1992.
14 J. H. Lin, C. M. Che, T. F. Lai, C. K. Poon and Y. X. Cui, J. Chem.
Soc., Chem. Commun., 1991, 468.
15 Z. Gross, S. Ini, M. Kapon and S. Cohen, Tetrahedron Lett., 1996,
37, 7325.
16 J. A. Smegal, B. C. Schardt and C. L. Hill, J. Am. Chem. Soc., 1983,
105, 3510; J. A. Smegal and C. L. Hill, J. Am. Chem. Soc., 1983, 105,
3515.
Acknowledgements
We acknowledge support from The University of Hong Kong
and the Hong Kong Research Grants Council.
17 R. B. Van Atta, C. C. Franklin and J. S. Valentine, Inorg. Chem.,
1984, 23, 4121.
18 W. Zhang, J. L. Loebach, S. R. Wilson and E. N. Jacobsen, J. Am.
Chem. Soc., 1990, 112, 2801; P. J. Pospisil, D. H. Carsten and
E. N. Jacobsen, Chem. Eur. J., 1996, 2, 974.
References
1 T. Katsuki and K. B. Sharpless, J. Am. Chem. Soc., 1980, 102, 5974;
M. G. Finn and K. B. Sharpless, Asymmetric Synthesis, ed.
J. D. Morrison, Academic Press, New York, 1985, vol. 5, p. 247;
H. C. Kolb, M. S. Van Nieuwenhze and K. B. Sharpless, Chem.
Rev., 1995, 94, 2483 and refs. therein.
2 E. N. Jacobsen, Catalytic Asymmetric Synthesis, ed. I. Ojima, VCH,
New York, 1993, p. 159; T. Katsuki, Coord. Chem. Rev., 1995, 140,
189.
Received 30th January 1997; Paper 7/00712D
3482
J. Chem. Soc., Dalton Trans., 1997, Pages 3479–3482