RESUMO
Two derivatives of trans-2-naphthyloxycyclohexanol were synthesized, their enantiomers were separated by enzyme mediated kinetic resolution and their absolute configuration was established by synthesizing their diastereomers with esters of known chiral description. Chiral alcohols were then used as chiral auxiliaries for the preparation of esters by coupling with racemic α-halo acids. During the coupling reactions with DCC and a suitable base, an efficient dynamic thermodynamic resolution was observed and the products were isolated in high diastereomeric purity. The effect of several parameters on the reaction was studied and the absolute configuration of a newly created chiral centre was established by single crystal X-ray analysis; the correlation of the structure of chiral auxiliary and diastereoselectivity was investigated. The observed diastereoselectivity was in accordance with the relative energy profile of the products. The chirally pure α-halo acid could be separated from the auxiliary, without any loss of optical purity of both components.
RESUMO
Optically pure 2-(quinolin-8-yloxy)cyclohexan-1-ol 1, obtained via simple chemical and bio-catalytic steps, was used as a chiral solvating agent for molecular recognition of the enantiomers of acids. The discrimination of isomers was detected by NMR or fluorescence spectroscopy. Isomers of α-substituted carboxylic acids, phosphoric acids, unprotected amino acids and dipeptides were efficiently detected, while the method can be used for quantitative determination for practical applications. Analysis of the crystal of (R,R)-1 (R)-mandelic acid established a three point supramolecular interaction.
RESUMO
Two diastereomers of optically active N,O-containing new macrocycles with dual chirality of the ring and pendent group were synthesized and characterized. The difference in the accessibility of the cavity was explored to discriminate the enantiomers of the derivatives of organo-phosphoric and phosphonic acids by (31)P NMR and fluorescence spectroscopy.
