Self immolation of prodrug1 to yield the chemotherapeutic drug doxorubicin. The doxorubicin prodrug (1) is cleaved by carboxypeptidase G2 (CPG2), releasing the glutamic acid (3) and an unstable intermediate (2). The latter undergoes a spontaneous 1,6 elimination, extruding doxorubicin (4), a quinone imine (5), and carbon dioxide. This scheme can be readily modified to allow the production of structurally similar drugs, such as daunorubicin.