Protection of the hydroxyl function of hydroxyproline and serine in peptide synthesis by the 2-methoxyethoxymethyl (Mem) group

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.

Development of a mild and efficient protocol for the protection and O-alkylation of allyl alcohols

An efficient, pyridine-free protocol has been developed for the protection of 3°-allyl alcohol of oxindole using a mild base of potassium carbonate under microwave irradiation conditions. The methodology has been tested with a variety of substrates and protecting group reagents, which provides a clean and good yield of desired products within a short reaction time.