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Evaluation of TlOH Effect for Pd<sup>0</sup>-Mediated Cross-Coupling of Methyl Iodide and Excess Boronic Acid Ester toward Fabrication of [<sup>11</sup>C]CH<sub>3</sub>-Incorporated PET Tracer
Division of Regeneration and Advanced Medical Science, Gifu University Graduated School of Medicine, Gifu University, Gifu, Japan
Division of Bio-function Dynamics Imaging, Riken Center for Life Science Technologies (CLST), 6-7-3 Minatojima Minamimachi, Kobe, Japan
Department of Clinical and Experimental Neuroimaging, Center for Development of Advanced Medicine for Dementia, National Center for Geriatrics and Gerontology, Obu-shi, Japan
- 1 Division of Regeneration and Advanced Medical Science, Gifu University Graduated School of Medicine, Gifu University, Gifu, Japan
- 2 Division of Bio-function Dynamics Imaging, Riken Center for Life Science Technologies (CLST), 6-7-3 Minatojima Minamimachi, Kobe, Japan
- 3 Department of Clinical and Experimental Neuroimaging, Center for Development of Advanced Medicine for Dementia, National Center for Geriatrics and Gerontology, Obu-shi, Japan
International Journal of Organic Chemistry·Volume 03 (2013)·Pages 220–223·Published 27 August 2013·DOI10.4236/ijoc.2013.33030
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Abstract
The use of thallium(I) hydroxide (TlOH) as a base is known to extremely accelerate the Suzuki-Miyaura cross-coupling reaction using organoboronic acid or organoboronic acid ester as a substrate. Here, we investigated the effects of TlOH by comparing with other conventional bases such as KOH, K 2 CO 3 , and CsF for Pd 0 -mediated rapid cross-coupling reactions between CH 3 I and organoborane reagents, such as phenyl-, ( Z )-4-benzyloxy-2-butenyl-, and benzylboronic acid pinacol esters under the conditions CH 3 I/borane/Pd 0 /base (1:40:1:3) in THF/H 2 O or DMF/H 2 O for 5 min with an aim to fabricate a PET tracer efficiently. Consequently, however, the use of TlOH was much less efficient than the other bases for the acceleration of cross-coupling reactions. Thus, it was reconfirmed that the milder and non-toxic conditions using K 2 CO 3 or CsF so far developed by our group were most appropriate for the rapid C -methylations.
KeywordsSynthesis of Short-Lived Positron Emission Tomography ProbesSuzuki-Miyaura-Type Rapid Cross-CouplingRapid C-MethylationTlOH
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