Highly Enhanced Enantioselectivity in the Memory of Chirality via Acyliminium Ions

Organic Letters

Volumn 4, Issue 11, 2002, Pages 1875-1877

  Wanyoike, G Ng'ang'a ^a   Onomura, Osamu ^a   Maki, Toshihide ^a   Matsumura, Yoshihiro ^a  

^a NAGASAKI UNIVERSITY   (Japan)

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EID: 0037575968     PISSN: 15237060     EISSN: None     Source Type: Journal    
DOI: 10.1021/ol025865r     Document Type: Article

References (17)

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3. (b) Sauer, S.; Schumacher, A.; Barbosa, F.; Giese, B. Tetrahedron Lett 1998, 39, 3685-3688.
4. (c) Giese, B.; Wettstein, P.; Stahelin, C.; Barbosa, F.; Neuburger, M.; Zehnder, M.; Wessig, P. Angew. Chem., Int. Ed. 1999, 38, 2586-2587.
5. Griesbeck, A. G.; Kramer, W.; Lex, J. Angew. Chem., Int. Ed. 2001, 40, 577-579.
6. (a) Matsumura, Y.; Shirakawa, Y.; Satoh, Y.; Umino, M.; Tanaka, T.; Maki, T.; Onomura, O. Org. Lett. 2000, 2, 1689-1691.
7. (b) Matsumura, Y.; Tanaka, T.; Wanyoike, G. N.; Maki, T.; Onomura, O. J. Electroanal. Chem. 2001, 507, 71-74.
8. (c) Davies, S. G.; Donohoe, T. J. Synlett 1993, 323-332.
9. The original chirality is conformationally memorized in those reactive intermediates. Thus, the well-known retention of configuration caused by neighboring effects in carbocation chemistry is excluded from the definition.
10. Greene, T. W.; Wuts, P. G. M. Protective Groups in Organic Synthesis, 2nd ed.; John Wiley and Sons: New York, 1991; pp 315-403, 41-452.
11. Shibasaki M.; Takamura, M.; Funabashi, K.; Kanai, M. J. Am. Chem. Soc. 2000, 122, 6327-6328; 2001, 123, 6801-6088.
12. Shibasaki M.; Takamura, M.; Funabashi, K.; Kanai, M. J. Am. Chem. Soc. 2000, 122, 6327-6328; 2001, 123, 6801-6088.
13. The ee of 2b was determined by HPLC analysis employing a Daicel Chiralpak OD.
14. 4a
15. 11
16. The de for the methoxylated product of threonine and allo-threonine derivatives 3 and 5, respectively, were determined using both Daicel Chiralpak OD and YMC-Pac SIL HPLC columns.
17. Electrolysis of 1b at room temperature afforded 2b (57% ee). The fact that this ee of 2b was lower than that obtained when the reaction was performed at -30 °C (80% ee) indicated that the facial selectivity was dependent on the temperature.