Carbon-11 carboxylation of trialkoxysilane and trimethylsilane derivatives using [¹¹C]CO₂

Abstract

A simple and rapid carbon-11 carboxylation radiosynthesis method.

Radiosynthesis, Preclinical, and Clinical Positron Emission Tomography Studies of Carbon-11 Labeled Endogenous and Natural Exogenous Compounds

“… ,, The product was obtained within 10–20 min with a RCY of 60–80% at EOB. ,, The simplicity made [ 11 C]­benzoic acid the substrate of choice for carboxylation and carbonylation studies. Several methods have been developed in the past year using [ 11 C]­benzoic acid and [ 11 C]­benzoate as pilot compounds, such as fluoride-mediated desilylative methods, , copper-catalyzed labeling of arylstannanes, palladium-catalyzed 11 C-carbonylation with [ 11 C]­CO, and 11 C-carboxylation of arylboronic esters via copper catalysis …”

Silicon compounds in carbon-11 radiochemistry: present use and future perspectives

“…20,[46][47][48][49] Trialkylsilyl and trialkoxysilyl arenes showed high reactivity towards copper-catalysed desilylative carboxylation reactions. 50 With the aid of a fluoride source, the precursor was initially converted into a pentavalent silyl fluoride anion which then undergoes oxidative addition onto the Cu catalyst and react with the cyclotron-produced [ 11 C]CO 2 . The highest reactivity was achieved when using DMF as solvent, KF/Kryptofix® 222 (crypt-222, 0.25 equiv.)…”

“…This method resulted equally efficient in the radiolabelling of alkynyl, aryl and heteroaryl precursors in short times (12 min) and with RCYs ranging between 19% and 93% (estimated by radioHPLC). 50 A similar methodology that did not require copper catalysis was developed, as well. Besides the production of 11 C-carboxylic acids, the interaction between alkylsilyl precursors and [ 11 C]CO 2 showed to effectively yield other moieties, such as 11 C-N-methylamines.…”

“…This method resulted equally efficient in the radiolabelling of alkynyl, aryl and heteroaryl precursors in short times (12 min) and with RCYs ranging between 19% and 93% (estimated by radioHPLC). 50 …”

“…The radiolabelling on heteroatoms (O, N, S), aryl and alkyl precursors was readily accomplished by either copper-catalysed or fluoride-activated desilylative reactions and two biologically-active molecules such as [ 11 C]propiophenone and [ 11 C]ibuprofen were also produced (isolated decay-corrected RCYs = 68% and 27%, respectively, Scheme 12 ). 50,51 …”