title: Multiple-turnover isotopic labeling of Fmoc- and Boc-protected amino acids with oxygen isotopes.
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.
authors.affiliation: Institute of Organic Chemistry, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland.
authors.forename: Martin S
authors.initials: MS
authors.lastname: Seyfried
authors.forename: Birgit S
authors.initials: BS
authors.lastname: Lauber
authors.forename: Nathan W
authors.initials: NW
authors.lastname: Luedtke
mesh_terms: D000596:Amino Acids / Q000737:chemistry*; D002264:Carboxylic Acids / Q000737:chemistry*; D007553:Isotope Labeling; D015394:Molecular Structure; D010103:Oxygen Isotopes / Q000737:chemistry*
chemical_list: D000596:Amino Acids; D002264:Carboxylic Acids; D010103:Oxygen Isotopes