A closer look on various synthetic routes to Callystatin A: a cytotoxic marine sponge polyketide

Callystatin A, a polyketide marine natural product, has been known since 1997 after its isolation from the sponge Callyspongia truncata by Kobayashi et al. It belongs to the leptomcyin family of natural products with a highly conjugated and stereodefined skeleton. The challenging structural topographies and remarkable anti-proliferative properties of (?)-Callystatin A stimulated many researchers to pursue the total synthesis of this marine polyketide. This review is exclusively focused on the research undertaken towards the concise, asymmetric total synthesis of Callystatin A over the last two decades. The various target oriented synthetic pathways are discussed in a chronological order to give a comprehensive overview.