Use of a bis-lithium amide base in asymmetric metallation of tricarbonyl(η6-1,3-dihydroisobenzothiophene)chromium(0)

Tetrahedron Asymmetry

Volumn 9, Issue 15, 1998, Pages 2563-2566

  Ariffin, Azhar ^a   Blake, Alexander J ^a   Ewin, Richard A ^a   Simpkins, Nigel S ^a  

^a UNIVERSITY OF NOTTINGHAM   (United Kingdom)

Author keywords

[No Author keywords available]

Indexed keywords

CHROMIUM DERIVATIVE; TRICARBONYL(ETA6 1,3 DIHYDROISOBENZOTHIOPHENE)CHROMIUM; UNCLASSIFIED DRUG;

ARTICLE; CHEMICAL ANALYSIS; CHEMICAL REACTION; DRUG SYNTHESIS; ENANTIOMER; PRIORITY JOURNAL; STEREOCHEMISTRY;

EID: 0032493668     PISSN: 09574166     EISSN: None     Source Type: Journal    
DOI: 10.1016/S0957-4166(98)00267-5     Document Type: Article

References (17)

1. For reviews, see (a) O'Brien, P. J. Chem. Soc., Perkin Trans. 1 1998, 1439. (b) Cox, P. J.; Simpkins, N. S. Tetrahedron: Asymmetry 1991, 2, 1. Simpkins, N. S. In Advances in Asymmetric Synthesis; Stephenson, G. R., Ed., Blackie Academic, 1996; pp. 111-125. Koga, K. Pure and Appl. Chem. 1994, 66, 1487.
2. For reviews, see (a) O'Brien, P. J. Chem. Soc., Perkin Trans. 1 1998, 1439. (b) Cox, P. J.; Simpkins, N. S. Tetrahedron: Asymmetry 1991, 2, 1. Simpkins, N. S. In Advances in Asymmetric Synthesis; Stephenson, G. R., Ed., Blackie Academic, 1996; pp. 111-125. Koga, K. Pure and Appl. Chem. 1994, 66, 1487.
3. For reviews, see (a) O'Brien, P. J. Chem. Soc., Perkin Trans. 1 1998, 1439. (b) Cox, P. J.; Simpkins, N. S. Tetrahedron: Asymmetry 1991, 2, 1. Simpkins, N. S. In Advances in Asymmetric Synthesis; Stephenson, G. R., Ed., Blackie Academic, 1996; pp. 111-125. Koga, K. Pure and Appl. Chem. 1994, 66, 1487.
4. For reviews, see (a) O'Brien, P. J. Chem. Soc., Perkin Trans. 1 1998, 1439. (b) Cox, P. J.; Simpkins, N. S. Tetrahedron: Asymmetry 1991, 2, 1. Simpkins, N. S. In Advances in Asymmetric Synthesis; Stephenson, G. R., Ed., Blackie Academic, 1996; pp. 111-125. Koga, K. Pure and Appl. Chem. 1994, 66, 1487.
5. (a) Ewin, R. A.; Price, D. A.; Simpkins, N. S.; MacLeod, A. M.; Watt, A. P. J. Chem. Soc., Perkin Trans. 1 1997, 401.
6. (b) For a more recent contribution, see Ariffin, A.; Blake, A. J.; Li, W.-S.; Simpkins, N. S. Synlett 1997, 1453.
7. For a recent application of this method, see Quattropani, A.; Anderson, G.; Bernardinelli, G.; Kündig, E. P. J. Am. Chem. Soc. 1997, 119, 4773.
8. Cowton, E. L. M.; Gibson, S. E. (née Thomas).; Schneider, M. J.; Smith, M. H. Chem. Commun. 1996, 839.
9. Gibson, S. E. (née Thomas); Ham, P.; Jefferson, G. R.; Smith, M. H. J. Chem. Soc., Perkin Trans. 1 1997, 2161.
10. Synthesis of diamine corresponding to 8, see Bambridge, K.; Begley, M. J.; Simpkins, N. S. Tetrahedron Lett. 1994, 35, 3391.
11. 3SCr requires M, 285.9756).
12. Reactions conducted using 8 in the absence of LiCl gave little or no product, indicating that the presence of salt greatly facilitates the rate of metallation. Small amounts of chiral products from such reactions did however show similar ee levels to those from 'added salt' reactions, indicating that LiCl does not seem to enhance the level of base enantioselectivity in these reactions. In some cases the use of more than ca. 0.5 equivalents of LiCl in combination with base 8 lead to substantial amounts of double alkylation.
13. Reaction with acetone also gave product in high enantiomeric excess (ca. 99%) but in a much reduced yield (20%), presumably due to enolisation problems.
14. The configuration shown is based on the collection of low temperature data, including Friedel equivalents, and by refinement of a Flack parameter [value -0.02(2)], see Flack, H. D. Acta Crystallogr., Sect. A 1983, 39, 876.
15. iPrOH (3-5%)-hexane as eluent.
16. For other examples of the use of chiral bis-lithium amides, see (a) Newcombe, N. J.; Simpkins, N. S. J. Chem. Soc., Chem. Commun., 1995, 831.
17. (b) Tierney, J. P.; Alexakis, A.; Mangeney, P. Tetrahedron: Asymmetry 1997, 8, 1019.