Synthesis of (2<i>S</i>,3<i>R</i>,4<i>R</i>)‑Dihydroxyisoleucine\nfor Use in Amatoxin\nSynthesis

We\nreport a streamlined synthesis of (2<i>S</i>,3<i>R</i>,4<i>R</i>)-4,5-dihydroxy isoleucine (DHIle),\nan amino acid found in α-amanitin, which appears to be critical\nfor toxicity. This synthetic route is transition metal-free and enables\nthe production of significant quantities of DHIle with suitable protection\nfor use in peptide synthesis. Its incorporation into a cytotoxic amatoxin\nanalog is reported.