Enantiomeric Separation of Chiral Alpha-(1-Naphthyl)Ethyl Ammonium Perchlorate by Silica Gel-Bound Chiral Pyridino-18-Crown-6 Ligands
BRIGHAM YOUNG UNIV PROVO UT DEPT OF CHEMISTRY
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The separation of alpha-L-NAPHTHYLETHYL ammonium perchlorate NapEt into its R and S forms using silica gel-bound dimethylpyridino-18- crown-6 ligand S,S-l with methanol as an element is reported. We also report the synthesis of a new silica gel-bound diphenyl-substituted pyridino-18-crown-6 ligand R,R-2 by the following reactions. Dimethyl chelidamate 7 was first alkylated with 11-iodoundec-l-ene 6 on the phenolic oxygen and the resulting ether diester was reduced to form 4-undecenyloxy-2,6-pyridinedimethanol 8. Tosylation of 8 gave ditosylate 9 which was cyclized with R,R-diphenyl- substituted tetraethylene glycol R,R-10 to form crown R,R-II. Ligand R,R- II was treated with triethoxysilane using a platinum catalyst. The resulting chiral crown-substituted triethoxysilane, R,R-12, was reacted with silica gel in toluene at 90 deg to attach the ligand to silica gel. The results of the separation of R- and S-NapEt using new silica gel-bound crown R,R-2 with methanol as the eluent are also presented.
- Inorganic Chemistry
- Organic Chemistry
- Physical Chemistry