1H NMR (400 MHz, CD3OD) δ 7.35-7.32 (dd, J = 5.5 Hz, 5.2 Hz, 2H), 7.11-7.06
(dd, J = 8.7 Hz, 8.7 Hz, 2H), 3.78-3.75 (dd, J = 6.4 Hz, 6.1 Hz, 1H), 3.28-3.27 (d, J = 4.4 Hz,
1H), 3.06-3.00 (m, 1H).
13C NMR (150.8 MHz, CD3OD) δ 169.7, 163.7, 161.2, 131.1, 131.0,
130.8, 130.2, 123.5, 115.5, 115.3, 53.7, 35.0.
19F NMR (376.3 MHz, CD3OD) δ -70.27.
HRMS
(HESI) m/z: [M]+ calcd for C13H11F9NO3 400.05998, found 400.05897.
1H NMR predict
13 C NMR PREDICT
Synthesis of Perfluoro-tert-butyl Tyrosine, for Application in 19F NMR, via a Diazonium-Coupling Reaction
Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
Org. Lett., Article ASAP
DOI: 10.1021/acs.orglett.6b02858
Publication Date (Web): December 6, 2016
Copyright © 2016 American Chemical Society
*E-mail: zondlo@udel.edu.
Abstract
A practical synthesis of the novel highly fluorinated amino acid Fmoc-perfluoro-tert-butyl tyrosine was developed. The sequence proceeds in two steps from commercially available Fmoc-4-NH2-phenylalanine via diazotization followed by diazonium coupling reaction with perfluoro-tert-butanol. In peptides, perfluoro-tert-butyl tyrosine was detected in 30 s by NMR spectroscopy at 500 nM peptide concentration due to nine chemically equivalent fluorines that are a sharp singlet by 19F NMR. Perfluoro-tert-butyl ether has an estimated σp Hammett substituent constant of +0.30.
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