Abstract
Multifunctional cyclopentadiene (Cp) ligands and their rhenium and 99mTc complexes were prepared by a versatile synthetic route. The properties of these Cp ligands can be tuned on demand, either during their synthesis (variation of R1) or through post-synthetic functionalization with two equal or different vectors (V1 and V2). Variation of these groups enables a combinatorial approach in the synthesis of bioorganometallic complexes. This is demonstrated by the preparation of Cp ligands containing both electron-donating and electron-withdrawing groups at the R1 position and their subsequent homo- or heterofunctionalization with biovector models (benzylamine and phenylalanine) under standard amide bond-formation conditions. All ligands can be coordinated to the fac-[Re(CO)3]+ and fac-[99mTc(CO)3]+ cores to give tetrafunctional complexes in straightforward and functional-group-tolerant procedures. The 99mTc complexes were prepared in one step, in 30 min, and under aqueous conditions from generator-eluted [99mTcO4]-.
Frei, Angelo