Novel urea-linked cinchona-calixarene hybrid-type receptors for efficient chromatographic enantiomer separation of carbamate-protected cyclic amino acids was written by Krawinkler, Karl Heinz;Maier, Norbert M.;Sajovic, Elisabeth;Lindner, Wolfgang. And the article was included in Journal of Chromatography A in 2004.Safety of (S)-1-(((9H-Fluoren-9-yl)methoxy)carbonyl)piperidine-2-carboxylic acid The following contents are mentioned in the article:
Two novel diastereomeric cinchona-calixarene hybrid-type receptors (SOs) were synthesized by inter-linking 9-amino(9-deoxy)-quinine (AQN)/9-amino(9-deoxy)-epiquinine (eAQN) and a calix[4]arene scaffold via an urea functional unit. Silica-supported chiral stationary phases (CSPs) derived from these SOs revealed, for N-protected amino acids, complementary chiral recognition profiles in terms of elution order and substrate specificity. The AQN-derived CSP showed narrow-scoped enantioselectivity for open-chained amino acids bearing π-acidic aromatic protecting groups, preferentially binding the (S)-enantiomers. In contrast, the eAQN congener exhibited broad chiral recognition capacity for open-chained as well as cyclic amino acids, and preferential binding of the (R)-enantiomers. Exceedingly strong retention due to nonenantioselective hydrophobic analyte-calixarene interactions observed with hydro-organic mobile phases could be largely suppressed with organic mobile phases containing small amounts of acetic acid as acidic modifier. With the eAQN-calixarene hybrid-type CSP particularly high levels of enantioselectivity could be achieved for tert-butoxycarbonyl (Boc)-, benzyloxycarbonyl (Z)- and fluorenylmethoxycarbonyl (Fmoc)-protected cyclic amino acids using chloroform as mobile phase, e.g. an enantioselectivty factor α > 5.0 for Boc-proline. Increasing amounts of acetic acid compromised enantioselectivity, indicating the crucial contributions of hydrogen bonding to chiral recognition. Comparison of the performance characteristics of the urea-linked eAQN-calixarene hybrid-type CSP with those of structurally closely related mutants provided evidence for the active involvement of the urea and calixarene units in the chiral recognition process. The urea linker motif was shown to contribute to analyte binding via multiple hydrogen bonding interactions, while the calixarene module is believed to support stereodiscrimination by enhancing the shape complementarity of the SO binding site. This study involved multiple reactions and reactants, such as (S)-1-(((9H-Fluoren-9-yl)methoxy)carbonyl)piperidine-2-carboxylic acid (cas: 86069-86-5Safety of (S)-1-(((9H-Fluoren-9-yl)methoxy)carbonyl)piperidine-2-carboxylic acid).
(S)-1-(((9H-Fluoren-9-yl)methoxy)carbonyl)piperidine-2-carboxylic acid (cas: 86069-86-5) belongs to piperidine derivatives.Piperidine is a key saturated heterocyclic scaffold found in several of the top-selling small molecule pharmaceuticals and natural alkaloids, with a diverse range of biological activities. Industrially, piperidine is produced by the hydrogenation of pyridine, usually over a molybdenum disulfide catalyst. Pyridine can also be reduced to piperidine via a modified Birch reduction using sodium in ethanol.Safety of (S)-1-(((9H-Fluoren-9-yl)methoxy)carbonyl)piperidine-2-carboxylic acid
Referemce:
Piperidine – Wikipedia,
Piperidine | C5H11N – PubChem