Synthesis of malformin‐A1, C, a glycan, and an aglycon analog: Potential scaffolds for targeted cancer therapy

Improvement in therapeutic efficacy while reducing chemotherapeutic side effects remains a vital objective in synthetic design for cancer treatment. In keeping with the ethos of therapeutic development and inspired by the Warburg effect for augmenting biological activities of the malformin family of cyclic‐peptide natural products, specifically anti‐tumor activity, a β‐glucoside of malformin C has been designed and synthesized utilizing precise glycosylation and solution phase peptide synthesis. We optimized several glycosylation procedures utilizing different donors and acceptors. The overarching goal of this study was to ensure a targeted delivery of a glyco‐malformin C analog through the coupling of D‐glucose moiety; selective transport via glucose transporters (GLUTs) into tumor cells, followed by hydrolysis in the tumor microenvironment releasing the active malformin C a glycon analog. Furthermore, total synthesis of malformin C was carried out with overall improved strategies avoiding unwanted side reactions thus increasing easier purification. We also report on an improved solid phase peptide synthesis protocol for malformin A1.