Salen as a chiral activator: Anti versus syn switchable diastereoselection in the enantio-selective addition of crotyl bromide to aromatic aldehydes

Angewandte Chemie - International Edition

Volumn 39, Issue 13, 2000, Pages 2327-2330

  Bandini, Marco ^a   Cozzi, Pier Giorgio ^a   Umani Ronchi, Achille ^a  

^a UNIVERSITY OF BOLOGNA   (Italy)

Author keywords

Asymmetric catalysis; Chromium; Diastereoselective synthesis; Molecular recognition; Schiff bases

Indexed keywords

ALDEHYDE; BROMINE DERIVATIVE;

ARTICLE; CHEMICAL REACTION; CHIRALITY; STEREOCHEMISTRY;

EID: 0034600784     PISSN: 14337851     EISSN: None     Source Type: Journal    
DOI: 10.1002/1521-3773(20000703)39:13<2327::AID-ANIE2327>3.0.CO;2-9     Document Type: Article

References (25)

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7. Commercially available crotyl bromide (85% tech.) was used.
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11. For the role of nonchiral additives and cocatalysis in catalytic asymmetric processes, see: E. M. Vogl, H. Gröger, M. Shibasaki, Angew. Chem. 1999, 111, 1671-1680; Angew. Chem. Int. Ed. 1999, 38, 1570-1577; for other interesting applications concerning the use of chiral activators in asymmetric catalysis, see: K. Mikami, S. Matsukuwa, Tetrahedron: Asymmetry 1995, 6, 2571-2574; K. Mikami, S. Matsukawa, Enantiomer 1996, 1, 69-73; K. Mikami, S. Matsukawa, Nature 1997, 385, 613-615.
12. For the role of nonchiral additives and cocatalysis in catalytic asymmetric processes, see: E. M. Vogl, H. Gröger, M. Shibasaki, Angew. Chem. 1999, 111, 1671-1680; Angew. Chem. Int. Ed. 1999, 38, 1570-1577; for other interesting applications concerning the use of chiral activators in asymmetric catalysis, see: K. Mikami, S. Matsukuwa, Tetrahedron: Asymmetry 1995, 6, 2571-2574; K. Mikami, S. Matsukawa, Enantiomer 1996, 1, 69-73; K. Mikami, S. Matsukawa, Nature 1997, 385, 613-615.
13. For the role of nonchiral additives and cocatalysis in catalytic asymmetric processes, see: E. M. Vogl, H. Gröger, M. Shibasaki, Angew. Chem. 1999, 111, 1671-1680; Angew. Chem. Int. Ed. 1999, 38, 1570-1577; for other interesting applications concerning the use of chiral activators in asymmetric catalysis, see: K. Mikami, S. Matsukuwa, Tetrahedron: Asymmetry 1995, 6, 2571-2574; K. Mikami, S. Matsukawa, Enantiomer 1996, 1, 69-73; K. Mikami, S. Matsukawa, Nature 1997, 385, 613-615.
14. For the role of nonchiral additives and cocatalysis in catalytic asymmetric processes, see: E. M. Vogl, H. Gröger, M. Shibasaki, Angew. Chem. 1999, 111, 1671-1680; Angew. Chem. Int. Ed. 1999, 38, 1570-1577; for other interesting applications concerning the use of chiral activators in asymmetric catalysis, see: K. Mikami, S. Matsukuwa, Tetrahedron: Asymmetry 1995, 6, 2571-2574; K. Mikami, S. Matsukawa, Enantiomer 1996, 1, 69-73; K. Mikami, S. Matsukawa, Nature 1997, 385, 613-615.
15. For the role of nonchiral additives and cocatalysis in catalytic asymmetric processes, see: E. M. Vogl, H. Gröger, M. Shibasaki, Angew. Chem. 1999, 111, 1671-1680; Angew. Chem. Int. Ed. 1999, 38, 1570-1577; for other interesting applications concerning the use of chiral activators in asymmetric catalysis, see: K. Mikami, S. Matsukuwa, Tetrahedron: Asymmetry 1995, 6, 2571-2574; K. Mikami, S. Matsukawa, Enantiomer 1996, 1, 69-73; K. Mikami, S. Matsukawa, Nature 1997, 385, 613-615.
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19. It is well accepted that oxo(salen)manganese(v) and azide(salen)-chromium(III) complexes exist in an equilibrium mixture of two enantio- or diastereomeric conformers: Y. N. Ito, T. Katsuki, Bull. Chem. Soc. Jpn. 1999, 72, 603-619, and references therein.
20. On the basis of the similar stepped structures of the oxo(salen)chromium complexes reported, we assumed that an analogous conformational equilibrium could involve the crotyl(salen)chromium(III) adduct 10, see: E. G. Samsel, K. Srinivasan, J. K. Kochi, J. Am. Chem. Soc. 1985, 107, 7606-7617; K. B. Hansen, J. L. Leighton, E. N. Jacobsen, J. Am. Chem. Soc. 1996, 118, 10924-10925.
21. On the basis of the similar stepped structures of the oxo(salen)chromium complexes reported, we assumed that an analogous conformational equilibrium could involve the crotyl(salen)chromium(III) adduct 10, see: E. G. Samsel, K. Srinivasan, J. K. Kochi, J. Am. Chem. Soc. 1985, 107, 7606-7617; K. B. Hansen, J. L. Leighton, E. N. Jacobsen, J. Am. Chem. Soc. 1996, 118, 10924-10925.
22. For studies concerning the influence of additives on the geometry and reactivity of [Mn(salen)] and [Cr(salen)] complexes, see: a) T. Hashihayata, T. Punniyamurthy, R. Irie, T. Katsuki, M. Akita, Y. Moro-oka, Tetrahedron 1999, 55, 14599-14610; b) K. M. Ryan, C. Bousquet, D. G. Gilheany, Tetrahedron Lett. 1999, 40, 3611-3616; c) A. M. Daly, C. T. Dalton, M. F. Renehan, D. G. Gilheany, Tetrahedron Lett. 1999, 40, 3617-3620.
23. For studies concerning the influence of additives on the geometry and reactivity of [Mn(salen)] and [Cr(salen)] complexes, see: a) T. Hashihayata, T. Punniyamurthy, R. Irie, T. Katsuki, M. Akita, Y. Moro-oka, Tetrahedron 1999, 55, 14599-14610; b) K. M. Ryan, C. Bousquet, D. G. Gilheany, Tetrahedron Lett. 1999, 40, 3611-3616; c) A. M. Daly, C. T. Dalton, M. F. Renehan, D. G. Gilheany, Tetrahedron Lett. 1999, 40, 3617-3620.
24. For studies concerning the influence of additives on the geometry and reactivity of [Mn(salen)] and [Cr(salen)] complexes, see: a) T. Hashihayata, T. Punniyamurthy, R. Irie, T. Katsuki, M. Akita, Y. Moro-oka, Tetrahedron 1999, 55, 14599-14610; b) K. M. Ryan, C. Bousquet, D. G. Gilheany, Tetrahedron Lett. 1999, 40, 3611-3616; c) A. M. Daly, C. T. Dalton, M. F. Renehan, D. G. Gilheany, Tetrahedron Lett. 1999, 40, 3617-3620.
25. syn = 87%).