Total Synthesis of Alloviroidin.

Alloviroidin is a cyclic heptapeptide, produced by several species of Amanita mushrooms, that demonstrates high affinity for F-actin as is characteristic of virotoxins and phallotoxins. Alloviroidin was synthesized via a [3 + 4] fragment condensation of Fmoc-d-Thr(OTBS)-d-Ser(OTBS)-(2 S,3 R,4 R)-DHPro(OTBS)2-OH and H-Ala-Trp(2-SO2Me)-(2 S,4 S)-DHLeu(5-OTBS)-Val-OMe to form bond A. The linear heptapeptide favored a turn conformation, facilitating cyclization between Val1 and d-Thr2 (position B). Global deprotection and HPLC purification afforded alloviroidin with NMR spectra in excellent agreement with the natural product.