Angewandte
Chemie
[15] The lower limit of the selectivity factor s for the epoxides was
[1] R. A. Johnson, K. B. Sharpless in Catalytic Asymmetric Synthesis
(Ed.: I. Ojima), VCH, New York, 1993, Chap. 4.1.
estimated by using the equation s = ln[1Àc(1 + ee)]/
ln[1Àc(1Àee)] in the reaction with 2-methylindole (ee is the
percentage enantiomeric excess of the ring-opened products;
yields of ring-opened products were used for conversion c.
[16] The amount of 2-methylindole was adjusted to obtain the
maximum yield possible with the highest enantiomeric excess for
the unconverted epoxides. As we use 0.6–0.7 equiv of 2-
methylindole, the maximum theoretical yield is 30–40%.
[2] K. B. Sharpless, Angew. Chem. 2002, 114, 2126 – 2135; Angew.
Chem. Int. Ed. 2002, 41, 2024 – 2032. For important method-
ologies for the preparation of optically active aromatic epoxides,
see T. Katsuki, Coord. Chem. Rev. 1995, 140, 189 – 214; b) Y. Tu,
Z.-X. Wang, Y. Shi, J. Am. Chem. Soc. 1996, 118, 9806 – 9807.
[3] J. M. Keith, J. F. Larrow, E. N. Jacobsen, Adv. Synth. Catal. 2001,
343, 5 – 2 6.
[4] a) M. Tokunaga, J. F. Larrow, F. Kakiuchi E. N. Jacobsen, Science
1997, 277, 937 – 938; b) J. F. Larrow, S. E. Schaus, E. N. Jacobsen,
J. Am. Chem. Soc. 1996, 118, 7420 – 7421; d) D. A. Annis, E. N.
Jacobsen, J. Am. Chem. Soc. 1999, 121, 4147 – 4154; e) R.
Breinbauer, E. N. Jacobsen, Angew. Chem. 2000, 112, 3750 –
3753; Angew. Chem. Int. Ed. 2000, 39, 3604 – 3607; f) J. M.
Ready, E. N. Jacobsen, J. Am. Chem. Soc. 2001, 123, 2687 – 2688;
g) J. M. Ready, E. N. Jacobsen, Angew. Chem. 2002, 114, 1432–
1435; Angew. Chem. Int. Ed. 2002, 41, 1374 – 1377.
À
[17] Methylidene cyclohexene oxide could be resolved with a C C
bond-forming reaction: a) F. Baldassi, P. Crotti, F. Macchia, M.
Pineschi, A. Arnold, B. L. Feringa, Tetrahedron Lett. 1998, 39,
7795 – 7798; b) F. Bertozzi, P. Crotti, F. Macchia, M. Pineschi, A.
Arnold, B. L. Feringa, Org. Lett. 2000, 2, 933 – 936.
[5] Kinetic resolution of 2,2-disubstituted epoxides catalyzed by
[Cr(salen)]: H. Lebel, E. N. Jacobsen, Tetrahedron Lett. 1999, 40,
7303 – 7306.
[6] Kinetic resolution of 1,2-disubstituted epoxides with enzymes:
K. Faber, Biotransformations in Organic Chemistry, Springer,
Berlin, 2000, pp. 135 – 136.
[7] Kinetic resolution of epoxides via C–heteroatom bond-forming
reactions: a) S. E. Schaus, E. N. Jacobsen, Tetrahedron Lett.
1996, 37, 7937 – 7940; b) S. E. Schaus, J. F. Larrow, E. N. Jacob-
sen, J. Org. Chem. 1997, 62, 4197 – 4199; c) L. E. Martinez, J. L.
Leighton, D. H. Carsten, E. N. Jacobsen, J. Am. Chem. Soc. 1995,
117, 5897 – 5898; d) M. H. Wu, E. N. Jacobsen, Tetrahedron Lett.
1997, 38, 1693 – 1696; e) E. N. Jacobsen, Acc. Chem. Res. 2000,
33, 421 – 431; f) J. Gu, M. J. Dirr, Y. Wang, D. L. Soper, B. De,
J. A. Wos, C. R. Johnson, Org. Lett. 2001, 3, 791 – 794.
[8] Important examples of ARO reactions of meso epoxides with
carbon nucleophiles: a) M. B. Cole, K. D. Shimizu, C. A.
Krueger, J. P. A. Harrity, M. L. Snapper, A. H. Hoveyda,
Angew. Chem. 1996, 108, 1776 – 1779; Angew. Chem. Int. Ed.
Engl. 1996, 35, 1668 – 1671; b) S. E. Schaus, E. N. Jacobsen, Org.
Lett. 2000, 2, 1001 – 1004; c) M. Lautens, J.-L. Renaud, S.
Hiebert, J. Am. Chem. Soc. 2000, 122, 1804 – 1805; d) M.
Lautens, C. Dockendorff, K. Fagnou, A. Malicki, Org. Lett.
2002, 4, 1311 – 1314; e) M. Lautens, K. Fagnou, S. Hiebert, Acc.
Chem. Res. 2003, 36, 48 – 58.
[9] M. Bandini, P. G. Cozzi, P. Melchiorre, A. Umani-Ronchi, J. Org.
Chem. 2002, 67, 5386 – 5389.
[10] a) E. N. Jacobsen, Acc. Chem. Res. 2000, 33, 421 – 431; b) M.
Bandini, P. G. Cozzi, A. Umani-Ronchi, Chem. Commun. 2002,
919 – 927.
[11] Other indoles (indole; 1-methyl-, 5-methoxy-, 5-bromo-, 5-
benzyloxy-, and 5-nitroindole) were less reactive than 2-
methyindole.
[12] Interestingly, the absolute configuration of isolated 1a was the
opposite of that in other kinetic resolutions carried out with
[Cr(salen)] and [Co(salen)] complexes, and this indicates that a
different mechanism is probably operative in this case. For
[Co(salen)]-catalyzed kinetic resolution, see S. E. Schaus, B. D.
Brandes, J. F. Larrow, M. Tokunaga, K. B. Hansen, A. E. Gould,
M. E. Furrow, E. N. Jacobsen, J. Am. Chem. Soc. 2002, 124,
1307 – 1315. For kinetic resolution employing [Cr(salen)], see
ref. [7e].
[13] S. E. Schaus, J. Brånalt, E. N. Jacobsen, J. Org. Chem. 1998, 63,
403 – 405.
[14] Absolute configurations of products 2a, 2 f, and 2i were
established by HPLC analysis by comparing the retention
times with those of authentic samples; for all other products
the absolute configuration was assigned by analogy.
Angew. Chem. Int. Ed. 2004, 43, 84 –87
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