New and Efficient Routes to Biomolecules Substituted with Cyclopentadienyltricarbonylrhenium and ‐Technetium Derivatives

The small, compact, robust, and nonpolar units of [CpM(CO)3] (M=Re, Tc) coupled with biomolecules may be considered as bioorganometallic entities of potential interest in the field of medicinal chemistry. However, the short half‐life of useful radionuclides (186Re t1/2=3.7 d, 188Re t1/2=16.8 h, 99mTc t1/2=6 h), the risks inherent in their use, and their cost have led chemists to search for novel synthetic strategies that allow the rapid introduction of the [CpM(CO)3] moiety as a late step in the course of synthesizing the target molecule. The present paper describes different strategies recently reported in the literature to tackle this problem.