ChemInform Abstract In order to develop reagents which are more efficient than MTPA (α-methoxy-α-trifluoromethylphenylacetic acid) for the determination of enantiomeric excess, several fluoroacetic esters such as (I) are prepared and the 1H and 19F chemical shift differences of their s-butyl ester, α-phenylethyl ester and α-phenylethylamide diastereomeric pairs measured. The presence of both a bulky group and a single fluorine atom, and also a heteroatom group in some cases, on the chiral carbon atom are shown to be an important structural requirement in designing improved reagents for the e.e. determination.
carboxylic acid esterscarboxylic acid esters (benzene compounds) Q 0530
-120Chemistry of Novel Compounds with Multifunctional Carbon Structure. Part 6. Synthetic Studies and 19F NMR Investigation of Novel α,. alpha.-Disubstituted Fluoroacetates.-The title compounds (VI) are transesterified with optically active alcohols or converted to chiral amides. The diastereomers thus obtained are subjected to 19F NMR analysis. The differences between the chemical shifts observed indicate that the carboxylic acid derived from (VI) can be employed in the determination of optical purities. -(TAKEUCHI, Y.; OGURA, H.; ISHII, Y.; KOIZUMI, T.; Chem.
In order to develop reagents which are more efficient than MTPA (α‐methoxy‐α‐trifluoromethylphenylacetic acid) for the determination of enantiomeric excess, several fluoroacetic esters such as (I) are prepared and the 1H and 19F chemical shift differences of their s‐butyl ester, α‐phenylethyl ester and α‐phenylethylamide diastereomeric pairs measured.
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