Total Synthesis and Stereochemical Assignment of Streptide. Author Nicholas Isley, Yusuke Endo, Zhi-Chen Wu, Brett Covington, Leah Bushin, Mohammad Seyedsayamdost, Dale Boger Publication Year 2019 Type Journal Article Abstract Streptide () is a peptide-derived macrocyclic natural product that has attracted considerable attention since its discovery in 2015. It contains an unprecedented post-translational modification that intramolecularly links the β-carbon (C3) of a residue 2 lysine with the C7 of a residue 6 tryptophan, thereby forming a 20-membered cyclic peptide. Herein, we report the first total synthesis of streptide that confirms the regiochemistry of the lysine-tryptophan cross-link and provides an unambiguous assignment of the stereochemistry (3 vs 3) of the lysine-2 C3 center. Both the 3 and the originally assigned 3 lysine diastereomers were independently prepared by total synthesis, and it is the former, not the latter, that was found to correlate with the natural product. The approach enlists a powerful Pd(0)-mediated indole annulation for the key macrocyclization of the complex core peptide, utilizes an underdeveloped class of hypervalent iodine(III) aryl substrates in a palladium-catalyzed C-H activation/β-arylation reaction conducted on a lysine derivative, and provides access to material with which the role of streptide and related natural products may be examined. Keywords Models, Molecular, Magnetic Resonance Spectroscopy, Catalysis, Chromatography, High Pressure Liquid, Tryptophan, Peptides, Cyclic, Lysine, Cyclization, Iodine, Palladium, Stereoisomerism Journal J Am Chem Soc Volume 141 Issue 43 Pages 17361-17369 Date Published 2019 Oct 30 ISSN Number 1520-5126 DOI 10.1021/jacs.9b09067 Alternate Journal J Am Chem Soc PMCID PMC6821584 PMID 31577142 PubMedPubMed CentralGoogle ScholarBibTeXEndNote X3 XML