Propargyl‐Substituted Thiocarbamoylbenzamidines of Technetium and Rhenium: Steps towards Bioconjugation with Use of Click Chemistry

Abstract

A new propargyl-substituted thiocarbamoylbenzamidine has been synthesized. The compound acts as a tetradentate ligand and forms stable complexes with {Re V O} 3+ and {Tc V O} 3+ cores. Click couplings of the resulting complexes with benzylazide lead to prototype triazole derivatives, which were analyzed by NMR and IR spectroscopy and mass spectrometry, [a]

Reactivity of [ReOCl3(PPh3)2] Towards Substituted Anilines

“…The elemental analyses are in good agreement with the proposed structures (see experimental section). 1 H, 13 C, 31 P, and 19 F NMR spectra in solution (Figures S7-S29 in SI) and high-resolution mass spectrometry (Figures S30-S43 in SI) were also helpful in the determination of the coordination environment around the rhenium(V) metal center.…”

“…The incorporation of a functional group (i. e. amine or carboxylic group) in the organic moiety of the imido NR 2 À ligand in the [Re=NÀ R] 3 + core may provide an anchor for coupling reactions of the resulting rhenium(V) complex to biologically relevant molecules and may help to control the biodistribution of the radiopharmaceutical. [13] In 1962, Chatt and Rowe reported the first synthesis, isolation, and characterization of rhenium arylimido complexes. [14] Since then, a few analogous complexes [Re-(NAr)X 3 (EPh 3 ) 2 ] (X = Cl, Br; E = P, As) were reported.…”

“…[38,39] Therefore, it is not surprising that many rhenium(V) imido compounds were applied as catalysts in different organic transformations like amination of diazo esters, [33] oxidation of alkanes and hydrocarbons with peroxides, [34] or oxidation of alkanes and alcohols with tert-butyl hydroperoxide (TBHP). [35,36] In the context of the considerations mentioned above, a series of rhenium(V) imido complexes [Re(NR)Cl 3 (PPh 3 ) 2 ] were synthesized and characterized by elemental analysis, electrospray ionization high-resolution mass spectrometry, 1 H, 13 C{ 1 H}, 19…”

Advances in Development of Radiometal Labeled Amino Acid-Based Compounds for Cancer Imaging and Diagnostics

“…New clickable chelators have been designed for 99m Tc-labeled peptides to obtain an increased hydrophilicity and decreased hepatobiliary retention of ([ 99m Tc]Tc(CO) 3 )-complexes. Novel dipicolylamine derivatives, substituted with carboxylates on the pyridyl rings, were synthesized and evaluated for fac -[Tc/Re I (CO) 3 ] + complexation with α-MSH peptide analogue [ 98 ]; a propargyl-substituted thiocarbamoylbenzamidine acting as a tetradentate ligand for a conjugation with [Re/Tc V O] 3+ cores [ 99 ]; or 1,4-substituted pyridyl-1,2,3-triazole derivatives with pendent phenyl isothiocyanate groups [ 100 ].…”

Copper-free click bioconjugation of technetium-99m complexes using strained cyclononyne derivatives

“…25 Several approaches with the 99m Tc-tricarbonyl core and click chemistry are known using the tetrazine click reaction, 26,27 the click-to-chelate approach 28 or the Cu-catalysed click version. [29][30][31] One example is known to the best of our knowledge using SPAAC for 99m Tc-radiolabelling. 32 Here, our aim is to synthesise a new and convenient click system with DACN as the alkyne basis connected with the DPA chelator for 99m Tc-tricarbonyl for an easy and Cu-free click-labelling procedure.…”