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Updated: Jun 17, 2026

Protease- and Acid-catalyzed Labeling Workflows Employing 18O-enriched Water
Published on: February 20, 2013
Multiple-turnover isotopic labeling of Fmoc- and Boc-protected amino acids with oxygen isotopes
Martin S Seyfried1, Birgit S Lauber, Nathan W Luedtke
1Institute of Organic Chemistry, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland.
Abstract:
An efficient method for the selective isotopic labeling of carboxylic acids is reported. By reacting an amino acid with excess carbodiimide and (18)OH(2), a kinetically enhanced multiple turnover reaction provides the (18)O-labeled product in high yield and excellent isotopic enrichment. This reaction is fully compatible with standard Fmoc, Boc, Trt, and OtBu protecting groups and provides a means to selectively label the alpha-carboxylic acids of functionalized amino acids with stable oxygen isotopes.
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