Complexation with barium(II) allows the inference of the absolute configuration of primary amines by NMR [2]

Journal of the American Chemical Society

Volumn 121, Issue 41, 1999, Pages 9724-9725

  López, Blanca ^a   Quiñoá, Emilio ^a   Riguera, Ricardo ^a  

^a UNIVERSITY OF SANTIAGO DE COMPOSTELA   (Spain)

Author keywords

[No Author keywords available]

Indexed keywords

ALCOHOL; AMINE; BARIUM; METAL;

CHEMICAL ANALYSIS; CHEMICAL STRUCTURE; COMPLEX FORMATION; CONFORMATION; LETTER; NUCLEAR MAGNETIC RESONANCE; PROTON NUCLEAR MAGNETIC RESONANCE; STEREOCHEMISTRY; STRUCTURE ANALYSIS;

EID: 0041800510     PISSN: 00027863     EISSN: None     Source Type: Journal    
DOI: 10.1021/ja990597m     Document Type: Letter

References (21)

1. For a review on the use of NMR for the assignment of absolute configuration and ee measurements see: Uray, G. Houben-Weyl: Methods in Organic Chemistry; Helmchen, G., Hoffmann, R. W., Mulzer, J., Schaumann, E., Eds.; Thieme: Stuttgart/New York, 1996; Vol. 1, p 253.
2. (a) Seco, J. M.; Latypov, Sh. K.; Quiñoá, E.; Riguera, R. Tetrahedron: Asymmetry 1995, 6, 107-110.
3. (b) Seco, J. M.; Latypov, Sh. K.; Quiñoá, E.; Riguera, R. Tetrahedron 1997, 53, 8541-8564.
4. Latypov, Sh. K.; Seco, J. M.; Quiñoá, E.; Riguera, R. J. Am. Chem. Soc. 1998, 120, 877-882.
5. Sullivan, G. R.; Dale, J. A.; Mosher, H. S. J. Org. Chem. 1973, 38, 2143-2147.
6. Trost, B. M.; Bunt, R. C.; Pulley, Sh. R. J. Org. Chem. 1994, 59, 4202-4205.
7. (a) Latypov, Sh. K.; Seco, J. M.; Quiñoá, E.; Riguera, R. J. Org. Chem. 1995, 60, 1538-1545.
8. (b) Seco, J. M.; Latypov, Sh. K.; Quiñoá, E.; Riguera, R. J. Org. Chem. 1997, 62, 7569-7574.
9. (c) Seco, J. M.; Quiñoá, E.; Riguera, R. J. Org. Chem. 1999, 64, 4669-4675.
10. (d) Hoye, T. R.; Renner, M. K. J. Org. Chem. 1996, 61, 8489-8495.
11. (e) García-Martínez, C.; Taguchi, Y.; Oishi, A.; Hayamizu, K. Magn. Res. Chem. 1998, 36, 429-435.
12. 2+ perchlorates induced downfield shifts of 0.03, 0.08, and 0.11 ppm, respectively, for 2-Me.
13. 2).
14. All compounds were synthesized and purified according to standard procedures (see ref 6a for amides, ref 2b for esters) from commercial compounds of known absolute configuration. All compounds gave satisfactory analytical and spectral data.
15. 1H NMR spectrum was recorded. Caution! Although no problems were encountered during the course of this work (the barium salt is employed only in minute amounts), attention is drawn to the potentially explosive nature of perchlorates.
16. 2+, can be found in the Supporting Information.
17. In the case of esters, the composition of the conformational equilibrium is known to be shifted in the opposite way to amides: i.e., the sp conformer is the most populated one. For more information see: (a) Latypov, Sh. K.; Seco, J. M.; Quiñoá, E.; Riguera, R. J. Org. Chem. 1995, 60, 504-515. (b) Latypov, Sh. K.; Seco, J. M.; Quiñoá, E.; Riguera, R. J. Org. Chem. 1996, 61, 8569-8577.
18. In the case of esters, the composition of the conformational equilibrium is known to be shifted in the opposite way to amides: i.e., the sp conformer is the most populated one. For more information see: (a) Latypov, Sh. K.; Seco, J. M.; Quiñoá, E.; Riguera, R. J. Org. Chem. 1995, 60, 504-515. (b) Latypov, Sh. K.; Seco, J. M.; Quiñoá, E.; Riguera, R. J. Org. Chem. 1996, 61, 8569-8577.
19. For a MPA ester, the population of the already dominant sp conformer becomes even larger, thus generating selective shielding/deshielding on both sides of the chiral center. The overall result implies a pattern for the Δδ signs that is the same as those of amides.
20. 2O.
21. Experiments carried out with 0.5 mg of substrate gave satisfactory results.