An update on new methods to synthesize cyclotetrapeptides.

Cyclotetrapeptides are important bioactive lead drug molecules that display a wide spectrum of pharmacological activities. However, the synthesis of cyclotetrapeptides from their linear precursors is challenging due to the highly constrained conformation required for cyclisation, thus hampering their progress to a clinical setting. This review provides an account of the reported methods used for the synthesis of cyclotetrapeptides.