title: Gold-catalyzed direct alkynylation of tryptophan in peptides using TIPS-EBX.
abstract: The selective functionalization of peptides containing only natural amino acids is important for the modification of biomolecules. In particular, the installation of an alkyne as a useful handle for bioconjugation is highly attractive, but the use of a carbon linker is usually required. Herein, we report the gold-catalyzed direct alkynylation of tryptophan in peptides using the hypervalent iodine reagent TIPS-EBX (1-[(triisopropylsilyl)ethynyl]-1,2-benziodoxol-3(1H)-one). The reaction proceeded in 50-78% yield under mild conditions and could be applied to peptides containing other nucleophilic and aromatic amino acids, such as serine, phenylalanine or tyrosine.
authors.affiliation: Laboratory of Catalysis and Organic Synthesis, Ecole Polytechnique Fédérale de Lausanne, EPFL SB ISIC LCSO, BCH 4306, 1015 Lausanne, Switzerland; Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden.
authors.forename: Gergely L
authors.initials: GL
authors.lastname: Tolnai
authors.affiliation: Laboratory of Catalysis and Organic Synthesis, Ecole Polytechnique Fédérale de Lausanne, EPFL SB ISIC LCSO, BCH 4306, 1015 Lausanne, Switzerland; Givaudan, Chemin de la parfumerie 5, 1214 Vernier, Switzerland.
authors.forename: Jonathan P
authors.initials: JP
authors.lastname: Brand
authors.affiliation: Laboratory of Catalysis and Organic Synthesis, Ecole Polytechnique Fédérale de Lausanne, EPFL SB ISIC LCSO, BCH 4306, 1015 Lausanne, Switzerland.
authors.forename: Jerome
authors.initials: J
authors.lastname: Waser
keywords: C–H functionalization; alkynes; gold catalysis; hypervalent iodine; peptides