"Mix and shake" method for configurational assignment by NMR: Application to chiral amines and alcohols

Organic Letters

Volumn 5, Issue 17, 2003, Pages 2979-2982

  Porto, Silvia ^a   Durán, Juan ^a   Seco, José Manuel ^a   Quiñoá, Emilio ^a   Riguera, Ricardo ^a  

^a UNIVERSITY OF SANTIAGO DE COMPOSTELA   (Spain)

Author keywords

[No Author keywords available]

Indexed keywords

ALCOHOL DERIVATIVE; AMINE;

ARTICLE; CHIRALITY; METHODOLOGY; NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY;

EID: 0141632619     PISSN: 15237060     EISSN: None     Source Type: Journal    
DOI: 10.1021/ol034853i     Document Type: Article

References (25)

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10. Seco, J. M.; Tseng, L.; Godejohann, M.; Quiñoá, E.; Riguera, R. Tetrahedron: Asymmetry 2002, 13, 2149.
11. It is worth noting the complete selectivity obtained in the case of L-norephedrine (15) when using the conditions developed for amines (absence of DMAP): only the amino group was derivatized, leaving the alcohol group free.
12. -1; 87% calculated yield). Analogous procedures were employed with the other auxiliary reagents.
13. Carboxypolystyrene HL resin (100-200 mesh; loading = 1.4 mmol/ g) was employed. The polymer matrix was copoly(styrene-1% DVB).
14. 3 using toluene as an internal control).
15. In a typical experiment, 9.8 mg (13.7 μmol) of resin 1 were reacted with 0.7 μL (6.8 μmol) of amine 5.
16. 3; (2) MPA resin is added and the solution shaken; (3) the spectrum is recorded. In this way the evolution of the reaction can be monitored by observing the disappearance of the amine signals and the appearance of those corresponding to the amide [See in Supporting Information the monitoring of the transformation of 12 when reacted with 1:2 (R)/(S)-MPA resin].
17. 1H NMR spectra.
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21. 3, due to the different swelling properties of the resin in both solvents.
22. DMAP is added into the NMR tube with the other reagents. The procedures of the experiments are analogous to those with amines. A relationship alcohol/resin/DMAP 1/5/2 (equiv) was usually maintained. Longer reaction times than those of amines were necessary (5 h) for complete consumption of the starting alcohol. Strictly dry conditions are required. One or two beads of molecular sieves (4 Å) can be added into the NMR tube without causing any interference with the recording of the spectrum.
23. (a) Latypov, S. K.; Seco, J. M.; Quiñoá, E.; Riguera, R. J. Org. Chem. 1995, 60, 504.
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