Letter
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.
Supporting Information
The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.orglett.6b02858.
- Synthetic procedures, 1H, 13C, and 19F NMR spectra for small molecules, synthesis and characterization data for peptides, and additional NMR data for peptides (PDF)
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