- 1-(1)-dehydroabietylimidazolium salts as enantiomer discriminators for NMR spectroscopy
-
Nine new (+)-dehydroabietylimidazolium salts were synthesised and studied as chiral solvating agents for several different racemic aromatic and non-aromatic carboxylate salts. These cationic chiral solvating agents resolve racemic ionic analytes better than non-ionic ones. Bis(dehydroabietylimidazolium) bis(trifluoromethanesulfonimide) gave the best discrimination for the enantiomers of carboxylate salts. Its resolution behaviour was studied by an NMR titration experiment, which indicated 1 : 1 complexation with the racemic analyte. The dehydroabietylimidazolium salts were also useful in enantiomeric excess (ee) determinations, and for the recognition of chirality of racemic aromatic and nonaromatic a-substituted carboxylic acids.
- Gunaratne, H.Q. Nimal,Laaksonen, Tiina,Seddon, Kenneth R.,W?h?l?, Kristiina
-
p. 845 - 856
(2017/07/07)
-
- Synthesis and applications of secondary amine derivatives of (+)-dehydroabietylamine in chiral molecular recognition
-
(+)-Dehydroabietylamine (1a), the novel derivatives (2a-6a) and their NTf2 salts (1b-6b) were tested as chiral NMR solvating agents for the resolution of enantiomers of the model compound Mosher's acid (7) and its n-Bu4N salt (8). Best enantiomeric discrimination of 7 was obtained using bisdehydroabietylamino-N1,N2-ethane-1,2-diamine (6a), and of 8 using N-(dehydroabietyl)-2-(dehydroabietylamino)ethanaminium bis((trifluoromethyl)-sulfonyl)-amide (6b). For the maximal resolution of enantiomers of 8, 1.0 eq. of 6b were needed. However, 0.5 eq. of 6a sufficed for the maximal resolution of enantiomers of 7. Enantiomeric excess studies were successfully conducted using 6a and 6b. The capability of 6a and 6b to recognize the enantiomers of various α-substituted carboxylic acids and their n-Bu4N salts were examined. Best resolutions were observed for aliphatic and aromatic carboxylic acids bearing an electronegative α-substituent. Now the ee studies on such non-aromatic carboxylic acids are also feasible.
- Laaksonen, Tiina,Heikkinen, Sami,W?h?l?, Kristiina
-
p. 10548 - 10555
(2015/11/10)
-