Construction of the Pentacyclic Core and Formal Total Synthesis of (rac)-Renieramycin T.

Invited for this month's cover picture is the group of Professor Naoki Saito at the Graduate School of Pharmaceutical Sciences, Meiji Pharmaceutical University (Japan). They achieved the first total synthesis of renieramycin T in 2016, and they have been following an alternative route to supply a large amount of it in order to promote research of the next stage, such as structure-activity relationship studies. This paper reports a formal total synthesis in 21 steps from a known piperazine-2,5-dione derivative. The key step of this synthesis is the modified Pictet-Spengler cyclization of a primary amine with an oxomalonic acid ester derivative followed by decarboxylation, and stereo-controlled protonation at C-1 position of the enol intermediate from the less-hindered face. Read the full text of their Full Paper at https://doi.org/10.1002/open.201800112.