Sequential α‐Ketoacid‐Hydroxylamine (KAHA) Ligations: Synthesis of C‐Terminal Variants of the Modifier Protein UFM1

3 for 3: Sequential α-ketoacid–hydroxylamine (KAHA) ligations with 5-oxaproline allow access to the modifier protein UFM1 (Ubiquitin-fold modifier 1) with a C-terminal amide, carboxylic acid, or a masked thioester. Fmoc protection of an N-terminal 5-oxaproline permits the assembly of proteins of >80 residues in good yield by a two-pot process from three readily prepared medium-sized protein segments. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.