A simple procedure for the preparation of enantiopure ethyl α-hydroxyalkyl ketones

Tetrahedron Letters

Volumn 38, Issue 9, 1997, Pages 1633-1636

  Martín, Ricardo ^a   Pascual, Oscar ^a   Romea, Pedro ^a   Rovira, Roser ^a   Urpí, Fèlix ^a   Vilarrasa, Jaume ^a  

^a UNIVERSITY OF BARCELONA   (Spain)

Author keywords

[No Author keywords available]

Indexed keywords

KETONE DERIVATIVE;

ARTICLE; COMPLEX FORMATION; DRUG SYNTHESIS; ENANTIOMER; NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY; REACTION ANALYSIS;

EID: 0031550825     PISSN: 00404039     EISSN: None     Source Type: Journal    
DOI: 10.1016/S0040-4039(97)00107-X     Document Type: Article

References (25)

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6. 3. For a recent review on asymmetric aldol reactions, see: Franklin, A. S.; Paterson, I. Contemporary Organic Synthesis 1994, 1, 317.
7. 4. For representative examples, from amides and related derivatives: (a) Nahm, S.; Weinreb, S. M. Tetrahedron Lett. 1981, 22, 3815 [RCON(OMe)Me + R'M].
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9. 2=C(OEt)Li].
10. 2 + PhMgBr].
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13. 5. For an example of formation of N-acylpyrrolidines in this way, see: Ito, Y.; Kobayashi, Y.; Kawabata, T.; Takase, M.; Terashima, S. Tetrahedron 1989, 45, 5767. One carboxamide (4ay) was then reduced to the corresponding aldehyde with Red-Al.
14. 6. On heating, partial racemisation takes place, as expected. For instance, heating of 3b and pyrrolidine excess at 70 °C overnight gave a 15% of racemisation.
15. 7. For reviews, see: Greene, T. W.; Wuts, P. G. M. Protective Groups in Organic Synthesis, Wiley: New York, 1991. Kocienski, P. J. Protecting Groups; Thieme: Stuttgart, 1994.
16. 7. For reviews, see: Greene, T. W.; Wuts, P. G. M. Protective Groups in Organic Synthesis, Wiley: New York, 1991. Kocienski, P. J. Protecting Groups; Thieme: Stuttgart, 1994.
17. 8. Ether solutions (ca. 1 M) of ethyl-lithium were readily prepared from EtBr and Li. See: Brandsma, L.; Verkruijsse, H. Preparative Polar Organometallic Chemistry. 1; Springer-Verlag: Berlin, 1987. Commercially available 2 M THF solutions of EtMgCl, purchased from Aldrich, were utilised as received.
18. 9. For a review, see: Sibi, M. P. Org. Prep. & Proc. Int. 1993, 25, 15.
19. 2O complex.
20. 11. This ratio did not change along the time nor after ultrasound irradiation of the NMR sample (the equilibrium between the two species is immediately reached). The methylene protons of the major species under-went a downfield shift of 0.20 ppm; the N-Me protons also moved, Δδ = 0.22, but the OMe protons not at all. The methylene protons of the minor species did not change, while the N-Me protons were shifted 0.18 ppm and the N-OMe protons 0.36 ppm (!) at lower field as well.
21. 12. For reviews on complexation of α-& β-alkoxy carbonyls with Lewis acids, see: Reetz, M. T. Acc. Chem. Res. 1993, 26, 462. Shambayati, S.; Schreiber, S. L. In Comprehensive Organic Synthesis, Vol. 1; Pergamon Press: Oxford, 1991, p. 283. For a pioneering work, on β-alkoxy carbonyls, see: Keck, G. E.; Castellino, S. J. Am. Chem. Soc. 1986, 108, 3847 & Tetrahedron Lett. 1987, 28, 281. Also see: Mori, S.; Nakamura, M.; Nakamura, E.; Koga, N.; Morokuma, K. J. Am. Chem. Soc. 1995, 117, 5055.
22. 12. For reviews on complexation of α-& β-alkoxy carbonyls with Lewis acids, see: Reetz, M. T. Acc. Chem. Res. 1993, 26, 462. Shambayati, S.; Schreiber, S. L. In Comprehensive Organic Synthesis, Vol. 1; Pergamon Press: Oxford, 1991, p. 283. For a pioneering work, on β-alkoxy carbonyls, see: Keck, G. E.; Castellino, S. J. Am. Chem. Soc. 1986, 108, 3847 & Tetrahedron Lett. 1987, 28, 281. Also see: Mori, S.; Nakamura, M.; Nakamura, E.; Koga, N.; Morokuma, K. J. Am. Chem. Soc. 1995, 117, 5055.
23. 12. For reviews on complexation of α-& β-alkoxy carbonyls with Lewis acids, see: Reetz, M. T. Acc. Chem. Res. 1993, 26, 462. Shambayati, S.; Schreiber, S. L. In Comprehensive Organic Synthesis, Vol. 1; Pergamon Press: Oxford, 1991, p. 283. For a pioneering work, on β-alkoxy carbonyls, see: Keck, G. E.; Castellino, S. J. Am. Chem. Soc. 1986, 108, 3847 & Tetrahedron Lett. 1987, 28, 281. Also see: Mori, S.; Nakamura, M.; Nakamura, E.; Koga, N.; Morokuma, K. J. Am. Chem. Soc. 1995, 117, 5055.
24. 12. For reviews on complexation of α-& β-alkoxy carbonyls with Lewis acids, see: Reetz, M. T. Acc. Chem. Res. 1993, 26, 462. Shambayati, S.; Schreiber, S. L. In Comprehensive Organic Synthesis, Vol. 1; Pergamon Press: Oxford, 1991, p. 283. For a pioneering work, on β-alkoxy carbonyls, see: Keck, G. E.; Castellino, S. J. Am. Chem. Soc. 1986, 108, 3847 & Tetrahedron Lett. 1987, 28, 281. Also see: Mori, S.; Nakamura, M.; Nakamura, E.; Koga, N.; Morokuma, K. J. Am. Chem. Soc. 1995, 117, 5055.
25. 12. For reviews on complexation of α-& β-alkoxy carbonyls with Lewis acids, see: Reetz, M. T. Acc. Chem. Res. 1993, 26, 462. Shambayati, S.; Schreiber, S. L. In Comprehensive Organic Synthesis, Vol. 1; Pergamon Press: Oxford, 1991, p. 283. For a pioneering work, on β-alkoxy carbonyls, see: Keck, G. E.; Castellino, S. J. Am. Chem. Soc. 1986, 108, 3847 & Tetrahedron Lett. 1987, 28, 281. Also see: Mori, S.; Nakamura, M.; Nakamura, E.; Koga, N.; Morokuma, K. J. Am. Chem. Soc. 1995, 117, 5055.