Total synthesis of thaxtomin A and its stereoisomers and findings of their biological activities.

The first and facile total synthesis of thaxtomin A and its three stereoisomers has been achieved. The synthetic approach involves intramolecular nucleophilic cyclization of an amide toward a ketoamide group to produce a C-hydroxydiketopiperazine scaffold. The most amazing discovery was that each of the four stereoisomers of TA exhibits different phytotoxic, fungicidal, and antiviral activities.