502445-19-4

Upstream product

• 23288-61-1 ^99mtechnetium pertechnetate 
• 163932-31-8 [⁽⁹⁹⁾technetium(I)(carbonyl)3(H₂O)3] 
• 7732-18-5 water 

Relevant academic research and scientific papers

Metal-mediated retro Diels-Alder of dicyclopentadiene derivatives: A convenient synthesis of [(Cp-R)M(CO)3] (M = 99mTc, Re) complexes

The synthesis of piano-stool type complexes [(Cp-R)99mTc(CO)3] from water and, if possible, directly from [99mTcO4]- is a persisting challenge. Such complexes are very convenient for labeling biomolecules since they are small in size and innocent with respect to noncovalent interactions in biological systems. We found that [(Cp-R)99mTc(CO)3] can be prepared directly from the dimerized Diels-Alder precursors and from [99mTcO4]-. Since the concentration of the respective monomers in the reaction solutions was undetectable, the formation of [(Cp-R)99mTc(CO)3] must be based on a metal-mediated retro Diels-Alder reaction with concerted Cp coordination. The authenticity of the formed 99mTc complexes was confirmed by comparing their HPLC retention times with those of the structurally characterized rhenium surrogates. Besides the principle access to piano-stool complexes for radiopharmaceutical studies, a metal-mediated retro Diels-Alder reaction under concomitant formation of the corresponding piano-stool complex has, to our knowledge, not been observed before and might apply to other metal cations as wel. Copyright

Aqueous synthesis of derivatized cyclopentadienyl complexes of technetium and rhenium directed toward radiopharmaceutical application

Half-sandwich complexes of the type [(RCOCp)M(CO)3] with M = Re and 99(m)Tc were synthesized from [M(OH2)3-(CO)3]+ in water. The R group can be an organic residue or a receptor binding biomolecule with a spacer to cyclopentadienyl (Cp). This provides a general route to Cp complexes of technetium without the need for starting from [TcBr(CO)5]. The X-ray structure of [{C6H5CH2COC5 H4}Tc(CO)3] has been elucidated. The compound crystallizes in the monoclinic space group P21/c with a = 16.1454(9), b = 7.6300(6), and c = 12.3922(7) A and β = 107,792(6)°, We have chosen a serotonergic receptor ligand (WAY) as an example for the derivatization of Cp with a bioactive molecule. WAY is linked to Cp by an aliphatic chain of variable length, The half-sandwich complexes were prepared from water and organic solvents. The structure of [(WAY4-Cp)Re(CO)3] could be elucidated. The compound crystallizes in the monoclinic space group P21/c with a = 15.7112(6), b = 6.8775(3), and c = 25,5217(12) A and β = 103.778(5)°. Quantification of inhibition constants gave a clear structure-activity relationship. A single methylene group between the receptor binding site and the half-sandwich complex gave an IC50 of 217 nM for HT1A, whereas a butylene linker resulted in retention of the inhibition constant with an IC50 of 6 nM with respect to underivatized WAY. For use as radiopharmaceuticals, the compounds have also been prepared with 99mTc in quantitative yield.