Synthesis and Biological Evaluation of Epidithio‑, Epitetrathio‑, and bis-(Methylthio)diketopiperazines: Synthetic Methodology, Enantioselective Total Synthesis of Epicoccin G, 8,8′-<i>epi</i>-<i>ent</i>-Rostratin B, Gliotoxin, Gliotoxin G, Emethallicin E, and Haematocin and Discovery of New Antivi

An improved sulfenylation method for the preparation of epidithio-, epitetrathio-, and bis-(methylthio)­diketopiperazines from diketopiperazines has been developed. Employing NaHMDS and related bases and elemental sulfur or bis­[bis­(trimethylsilyl)­amino]­trisulfide (23) in THF, the developed method was applied to the synthesis of a series of natural and designed molecules, including epicoccin G (1), 8,8′-epi-ent-rostratin B (2), gliotoxin (3), gliotoxin G (4), emethallicin E (5), and haematocin (6). Biological screening of selected synthesized compounds led to the discovery of a number of nanomolar antipoliovirus agents (i.e., 46, 2,2′-epi-46, and 61) and several low-micromolar anti-Plasmodium falciparum lead compounds (i.e., 46, 2,2′-epi-46, 58, 61, and 1).