884323-17-5Relevant articles and documents
Synthesis of a sterically crowded atropisomeric 1,8-diacridylnaphthalene for dual-mode enantioselective fluorosensing
Mei, Xuefeng,Martin, Rhia M.,Wolf, Christian
, p. 2854 - 2861 (2007/10/03)
An efficient synthetic route to a sterically crowded 1,8- diheteroarylnaphthalene-derived enantioselective fluorosensor that operates in two different detection modes utilizing fluorescence lifetime and intensity has been developed. Screening of palladium-catalyzed Negishi, Kumada, Suzuki, Hiyama, and Stille coupling methods showed that the latter affords highly congested 1,8-diarylnaphthalenes in superior yields. Despite severe steric hindrance, axially chiral 1,8-bis(3-(3′,5′-dimethylphenyl)-9- acridyl)naphthalene, 1, was obtained in 68% yield from 1,8-dibromonaphthalene, 14, and 3-(3′,5′-dimethylphenyl)-9-tributyl-stannylacridine, 13, via two consecutive Stille cross-coupling steps using tetrakis(triphenylphosphine)- palladium(0) as catalyst in the presence of copper(II) oxide. The preparation of 1 involved formation of 4-(3′,5′-dimethylphenyl)-2-chlorobenzoic acid, 7, through microwave-assisted Suzuki coupling of 4-bromo-2-chlorobenzoic acid, 10, and 3,5-dimethylphenylboronic acid, 11, followed by regioselective amination with aniline and acridine ring construction in phosphorus oxybromide. Lithiation, subsequent treatment with trimethylstannyl chloride, and Stille cross-coupling then completed the five-reaction sequence providing 1 in 57% overall yield. The enantiomers of 1 were separated by semipreparative HPLC on a (R,R)-Whelk-O 1 column and successfully employed in enantioselective fluorosensing of N-t-Boc-protected serine, 20, glutamine, 22, proline, 23, and 2-hydoxy-2-methylsuccinic acid, 21. Fluorescence titration experiments with 23 revealed that both static and dynamic quenching occur with distinctive enantioselectivity. Addition of (R)-23 to a solution of (+)-1 in acetonitrile resulted in stronger fluorescence quenching than titration with the (S)-enantiomer of 23. The fluorescence lifetime, τ, of 1 was determined as 18.8 ns and steadily decreased to 7.5 and 6.8 ns in the presence of 0.1 M of (S)-23 and (R)-23, respectively.
Determination of enantiomeric excess and concentration of unprotected amino acids, amines, amino alcohols, and carboxylic acids by competitive binding assays with a chiral scandium complex
Mei, Xuefeng,Wolf, Christian
, p. 13326 - 13327 (2007/10/03)
A practical UV-vis sensing method for enantioselective microanalysis of unprotected amino acids, amines, amino alcohols, and carboxylic acids in aqueous solution has been developed. Both concentration and enantiomeric composition of a wide range of chiral
