{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,8]],"date-time":"2026-06-08T02:59:44Z","timestamp":1780887584365,"version":"3.54.1"},"reference-count":39,"publisher":"MDPI AG","issue":"12","license":[{"start":{"date-parts":[[2026,6,6]],"date-time":"2026-06-06T00:00:00Z","timestamp":1780704000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>The Gram-negative bacterium Pseudomonas aeruginosa produces a family of peptide siderophores called pyoverdines that play a vital role in the mechanisms by which it acquires iron from the environment. A key component of various pyoverdines is the presence of one or more copies of L-\u03b4-N-formyl-\u03b4-N-hydroxyornithine (fOHOrn) as an iron-binding residue. In this study, we have developed an improved preparation of a derivative of fOHOrn that is suitable for use in solid-phase peptide synthesis, incorporating a novel N-oxidation protocol and a mild final deprotection with HCl\/hexafluoroisopropanol (HFIP) that circumvents the unexpected deformylation of the fOHOrn side chain under acidic conditions. We have also devised a synthesis of the cyclic peptide component of pyoverdine D exploiting a selective side-chain deprotection strategy with HCl\/HFIP that allows the application of readily available amino acids with standard tert-butyl side-chain protection and which facilitates the cyclisation step. These innovations open the way towards the convergent preparation of various pyoverdines and also other natural products that contain fOHOrn residues.<\/jats:p>","DOI":"10.3390\/molecules31121988","type":"journal-article","created":{"date-parts":[[2026,6,8]],"date-time":"2026-06-08T02:32:46Z","timestamp":1780885966000},"page":"1988","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Towards the Synthesis of Pyoverdines: Preparation and Reactivity of the N-Formylhydroxyornithine Residue"],"prefix":"10.3390","volume":"31","author":[{"given":"Tianzhu","family":"Zhang","sequence":"first","affiliation":[{"name":"Department of Life Sciences, University of Bath, Bath BA2 7AY, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9307-0515","authenticated-orcid":false,"given":"Albert","family":"Bolhuis","sequence":"additional","affiliation":[{"name":"Department of Life Sciences, University of Bath, Bath BA2 7AY, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0569-0082","authenticated-orcid":false,"given":"Ian M.","family":"Eggleston","sequence":"additional","affiliation":[{"name":"Department of Life Sciences, University of Bath, Bath BA2 7AY, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,6,6]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1199","DOI":"10.1016\/S0140-6736(24)01867-1","article-title":"Global burden of bacterial antimicrobial resistance 1990\u20132021: A systematic analysis with forecasts to 2050","volume":"404","author":"Murray","year":"2024","journal-title":"Lancet"},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Venkateswaran, P., Vasudevan, S., David, H., Shaktivel, A., Shanmugam, K., Neelakantan, P., and Solomon, A.P. 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