5B59:
reference: Transition Metal-Free Tryptophan-Selective Bioconjugation of Proteins., Seki Y, Ishiyama T, Sasaki D, Abe J, Sohma Y, Oisaki K, Kanai M, J Am Chem Soc. 2016 Aug 31;138(34):10798-801. doi: 10.1021/jacs.6b06692. Epub, 2016 Aug 17. PMID: 27534812

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