Rhenium(v) oxocomplexes with novel pyrazolyl-based N₄- and N₃S-donor chelators

Abstract

The novel pyrazolyl-based ligands 3,5-Me2pz(CH2)2NH(CH2)2NH(CH2)2NH2 and pz*(CH2)2NH-Gly-CH2STrit (pz*=pz, 3,5-Me2pz, 4-(EtOOC)CH(2)-3,5-Me2pz) were synthesized, and their suitability to stabilize Re(V) oxocomplexes was evaluated using different starting materials, namely (NBu4)[ReOCl4], [ReOCl3(PPh3)2] and trans-[ReO2(py)4]Cl. Compound reacts with trans-[ReO2(py)4]Cl yielding the cationic compound [ReO(OMe){3,5-Me2pz(CH2)2N(CH2)2NH(CH2)2NH2}](BPh4) in a low isolated yield. In contrast, the neutral complexes [ReO{pz*(CH2)2NH-Gly-CH2S}] (pz*=pz, 3,5-Me2pz, 4-(EtOOCCH2)-3,5-Me2pz) were synthesized almost quantitatively by reacting [ReOCl3(PPh3)2] or (NBu4)[ReOCl4] with the trityl-protected chelators. The X-ray diffraction analysis of and confirmed the tetradentate coordination mode of the respective ancillary ligands. In the monoanionic chelator coordinates to the metal through four nitrogen atoms, while in the chelator is trianionic, coordinating to the metal through three nitrogens and one sulfur atom. Solution NMR studies of , including two-dimensional NMR techniques (1H COSY and 1H/13C HSQC), confirmed that the N3S coordination mode of the chelators is retained in solution. Unlike , complexes may be considered relevant in the development of radiopharmaceuticals, as further corroborated by the synthesis of the congener [99mTcO{pz(CH2)2-NH-Gly-CH2S}]. This radioactive compound was obtained from 99mTcO4- in aqueous medium, in almost quantitative yield and with high specific activity and radiochemical purity.

A new proton sponge polymer synthesized by RAFT polymerization for intracellular delivery of biotherapeutics

“…Materials N-Hydroxyethylethylenediamine (99% purity) and di-tert-butyl dicarbonate were purchased from Aldrich to use in the synthesis of tert-butyl(2-((tert-butoxycarbonyl)amino)ethyl)(2-hydroxyethyl)carbamate according to the procedure reported by Moura et al 41 Methacryloyl chloride was purchased from Aldrich. tert-Butyl(2-((tert-butoxycarbonyl)amino)ethyl)(2-hydroxyethyl)carbamate was methacrylated according to the procedure reported previously.…”

“…The amine containing monomer was synthesized according to the procedure shown in Scheme 1. The primary and secondary amine groups of N-(2-hydroxyethyl)ethylenediamine were rst protected using di-tert-butyl dicarbonate according to the procedure reported by Moura et al 41 Briey, N-(2-hydroxyethyl)ethylenediamine (0.024 mol, 2.43 ml) was dissolved in dry DCM (40 ml) at À10…”

“…The rst step was to protect the primary and secondary amine groups of N-hydroxyethylethylenediamine in order to prevent any possible unwanted side reactions. The amine groups were protected using di-tert-butyl dicarbonate (Boc) based on a method reported by Moura et al 41 The Boc group has been widely used in peptide synthesis for protection of a-and side chain-amine groups of amino acids. In the second step, the amine-protected product, tertbutyl (2-((tert-butoxycarbonyl)amino)ethyl)(2-hydroxyethyl)-carbamate, was reacted with methacryloyl chloride to prepare the nal methacrylate monomer following a method reported elsewhere.…”

Synthesis, characterization and cytotoxic activity of gallium(III) complexes anchored by tridentate pyrazole-based ligands

“…The compounds N-(2-aminoethyl)pyrazole, N-(2-hydroxybenzyl-2-pyrazolethyl)imine (HL 1 ) and N-(2-hydroxybenzyl-2-pyrazolethyl)amine (HL 4 ) were prepared according to the procedures described in the literature [10,11]. 1 H and 13 C NMR spectra were recorded in a Varian Unity 300 MHz spectrometer and 71 Ga NMR spectra in a Bruker Avance-500 MHz NMR spectrometer.…”

Bifunctional chelators for radiorhenium: past, present and future outlook

“…Fig.11Structure of the mono-oxorhenium(V) complex with the trans-[ReO(OMe)] 2+ core synthesised by Moura et al100 …”