J. Uenishi, J.-M. Beau, R. W. Armstrong and Y. Kishi, “Dramatic Rate Enhancement of Suzuki Diene Synthesis. Its Application to Palytoxin Synthesis,” Journal of the American Chemical Society, Vol. 109, No. 15, 1987, 109, pp. 4756-4758. The magnitude of acceleration is roughly estimated to be the following order: KOH (relative rate = 1), TlOEt (5), Ag2O (30), and TlOH (1000). TlOH conditions are effective in water. For the review, see: S. R. Chemler, D. Trauner and S. J. Danishefsky, “The B-Alkyl Suzuki-Miyaura Cross-Coupling Reaction: Development, Mechanistic Study, and Applications in Natural Product Synthesis,” Angewandte Chemie International Edition, Vol. 40, No. 24, 2001, pp. 4544-4568.

has been cited by the following article:

• TITLE: Evaluation of TlOH Effect for Pd0-Mediated Cross-Coupling of Methyl Iodide and Excess Boronic Acid Ester toward Fabrication of [11C]CH3-Incorporated PET Tracer

  AUTHORS: Hiroko Koyama, Hisashi Doi, Masaaki Suzuki

  KEYWORDS: Synthesis of Short-Lived Positron Emission Tomography Probes; Suzuki-Miyaura-Type Rapid Cross-Coupling; Rapid C-Methylation; TlOH

  JOURNAL NAME: International Journal of Organic Chemistry, Vol.3 No.3, September 25, 2013

  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, K2CO3, and CsF for Pd0-mediated rapid cross-coupling reactions between CH3I and organoborane reagents, such as phenyl-, (Z)-4-benzyloxy-2-butenyl-, and benzylboronic acid pinacol esters under the conditions CH3I/borane/Pd0/base (1:40:1:3) in THF/H2O or DMF/H2O 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 K2CO3 or CsF so far developed by our group were most appropriate for the rapid C-methylations.