Synthesis, reactions and structure of Cp′Tc(CO)3 derivatives

Castro, Hhk; Meetsma, Auke; Teuben, Jan H.; Vaalburg, W; Panek, K.; Ensing, G.

doi:10.1016/0022-328x(91)83025-y

Cited by 30 publications

(18 citation statements)

References 19 publications

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“…The Tc(I) low-spin d 6 configuration was first exploited by Abrams et al with the development of the first successful 99m Tc myocardial perfusion agent, 99m Tc(MIBI) 6 + . − More recently, the chemistry of Tc(I) has been more extensively explored since Alberto and co-workers developed a one-pot kit to prepare fac -[ 99m Tc(CO) 3 (H 2 O) 3 ] + . , The aquo ligands are labile and can be readily exchanged for mono-, di-, or tridentate ligands. Since the introduction of this kit, a wide range of ligands have been explored ranging from nido-carboranes to cyclopentadienyl, triazacyclononane, various single amino acids, or isothiocyanates. To date, however, this has not resulted in the development of any commercially available radiopharmaceuticals.…”

Section: Technetiummentioning

confidence: 99%

“…This can be explained by (i) the greater availability of PET cameras thanks to the widespread success of [ 18 F]FDG as an oncological, neurological, and inflammation tracer; (ii) improved availability of biomedical cyclotrons, which has greatly increased the number of radionuclide production sites around the globe; and (iii) an increase in the number of metal-based radiopharmaceuticals either recently approved by the FDA or in late-stage clinical trials. These include 68 Ga-and 64 Cu-labeled peptides for imaging somatostatin-receptor-positive tumors and metastatic prostate cancer as well as a 177 Lu-labeled octreotide derivative for treating somatostatin-receptor-positive gastroenteropancreatic neuroendocrine tumors. These developments have led to a surge in interest in exploring previously unavailable radionuclides with highly attractive properties for nuclear imaging and therapy, and the improved availability of these radionuclides has, in turn, provided close to limitless possibilities for tracer development.…”

Section: Introductionmentioning

confidence: 99%

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Radioactive Transition Metals for Imaging and Therapy

2018

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Nuclear medicine is composed of two complementary areas, imaging and therapy. Positron emission tomography (PET) and single-photon imaging, including single-photon emission computed tomography (SPECT), comprise the imaging component of nuclear medicine. These areas are distinct in that they exploit different nuclear decay processes and also different imaging technologies. In PET, images are created from the 511 keV photons produced when the positron emitted by a radionuclide encounters an electron and is annihilated. In contrast, in single-photon imaging, images are created from the γ rays (and occasionally X-rays) directly emitted by the nucleus. Therapeutic nuclear medicine uses particulate radiation such as Auger or conversion electrons or β − or α particles. All three of these technologies are linked by the requirement that the radionuclide must be attached to a suitable vector that can deliver it to its target. It is imperative that the radionuclide remain attached to the vector before it is delivered to its target as well as after it reaches its target or else the resulting image (or therapeutic outcome) will not reflect the biological process of interest. Radiochemistry is at the core of this process, and radiometals offer radiopharmaceutical chemists a tremendous range of options with which to accomplish these goals. They also offer a wide range of options in terms of radionuclide half-lives and emission properties, providing the ability to carefully match the decay properties with the desired outcome. This Review provides an overview of some of the ways this can be accomplished as well as several historical examples of some of the limitations of earlier metalloradiopharmaceuticals and the ways that new technologies, primarily related to radionuclide production, have provided solutions to these problems.

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Section: Technetiummentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Radioactive Transition Metals for Imaging and Therapy

2018

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“…The other medium CO pressure synthesis by Knight et al. to Tc 2 (CO) 10 was also not appropriate for the same reasons . Challenged by the fundamental question to prepare fac ‐[ 99 Tc(CO) 3 ] + ‐type complexes at ambient CO pressure, we bypassed 99 Tc 2 (CO) 10 and found a direct path to [ 99 TcCl 3 (CO) 3 ] 2− directly from [ 99 TcO 4 ] − or [ 99 TcOCl 4 ] − .…”

Section: Methodsmentioning

confidence: 99%

The “Carbonyl Story” and Beyond; Experiences, Lessons and Implications

Alberto

2020

ChemBioChem

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The complex [ 99m Tc(OH 2) 3 (CO) 3 ] + has become a versatile building block in radiopharmaceutical chemistry, applied by many groups worldwide. However, despite widespread efforts, only one compound has made it right the way through clinical trials. Along the way from its discovery to its development into an eventual product, the author experienced issues that he would handle differently in retrospect. In this article, these experiences are turned into "lessons" that might be helpful for young researchers finding themselves in similar situations. Beside issues with patenting and company strategies, the carbonyl story has provided scientific implications beyond its own story, and insights from which any future 99m Tc-based chemistry for radiopharmacy or molecular imaging might benefit. Carbon monoxide complexes are not a class of compounds one would immediately relate to imaging agents with short-lived radionuclides such as 99m Tc (t 1/2 = 6 h). As they are typically prepared under high pressure/high temperature conditions and in organic solvents, their syntheses seem to contradict any preparative requirements for routine application in hospitals. Indeed, such CO complexes were not supposed to find any application in the beginning, when the main question was about how to prepare complexes with the fac-[ 99 Tc(CO) 3 ] + core at ambient CO pressure. The question arose from the chase to the still elusive complex [Cp* 99 TcO 3 ], a homologue of the wellknown [Cp*ReO 3 ] (Cp* = [C 5 Me 5 ] À). [1] [ 99 Tc 2 (CO) 10 ] was prepared by an adapted rhenium synthesis [2] under medium-high pressure conditions at Los Alamos National Laboratory in Sattelberger's group. This method could though not be pursued in our labs since reactions in autoclaves with radioactive materials were not allowed. The other medium CO pressure synthesis by Knight et al. to Tc 2 (CO) 10 was also not appropriate for the same reasons. [3] Challenged by the fundamental question to prepare fac-[ 99 Tc(CO) 3 ] +-type complexes at ambient CO pressure, we bypassed 99 Tc 2 (CO) 10 and found a direct path to [ 99 TcCl 3 (CO) 3 ] 2À directly from [ 99 TcO 4 ] À or [ 99 TcOCl 4 ] À. [4] Subjecting many reductants to the reaction of [ 99 TcO 4 ] À to carbonyls, borane H 3 B•THF turned out to be the reductant of choice. This purely fundamental 99 Tc chemistry did not imply its use in radioimaging agents at all. This vista turned when we stated excellent water solubility and stability of [ 99 TcCl 3 (CO) 3 ] 2À or whatever formed from it in solution. We identified this compound as [ 99 Tc(OH 2) 3 (CO) 3 ] + , an organometallic semi-aquaion, as we termed it. Educated in the spirit of "no water/no air" in organometallic chemistry we learned in lesson 1 that [a

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“…Reduction of Na[TcO 4 ] with Zn/HCl or Al/AlCl 3 /ultrasound in the presence of a wide variety o f arenes in cyclohexane gives [Tc(r|-Ar) 2 ] + cations (29) in high yield. I f A 1 / A 1 C 1 3 was used as the reductant in the absence of ultrasound, partially substituted arenes underwent transalkylation, leading to product mixtures.…”

Section: Arene and Other N Complexesmentioning

confidence: 99%

“…I f A 1 / A 1 C 1 3 was used as the reductant in the absence of ultrasound, partially substituted arenes underwent transalkylation, leading to product mixtures. The bis(arene) cations (29) were also evaluated as potential heart-imaging agents. The reaction o f the cubane cluster Na[Tc 3 (OMe) 4 (CO) 9 ] (6) with H C 1 and benzene yields the benzenetricarbonyl complex [Tc(CO) 3 (T!-C 6 H 6 )]Cf (30).…”

Section: Arene and Other N Complexesmentioning

confidence: 99%