Sato Kazuyuki, Yuki Takashi, Yamaguchi Ryoji, Hamano Tetsuya, Tarui Atsushi, Omote Masaaki, Kumadaki Itsumaro, Ando Akira
Faculty of Pharmaceutical Sciences, Setsunan University, 45-1, Nagaotoge-cho, Hirakata, Osaka 573-0101, Japan.
J Org Chem. 2009 May 15;74(10):3815-9. doi: 10.1021/jo9004348.
Synthesis of alpha-CF(3) carbonyl compounds has been recognized to be difficult up to now because the polarization of CF(3)(delta-)-I(delta+) is opposite to that of CH(3)(delta+)-I(delta-), and this makes it difficult to introduce CF(3)(+) unit to enolates. We recently reported an effective alpha-trifluoromethylation of ketones by using Et(2)Zn with Rh catalyst, but the mechanism has not fully been cleared. Now, we carried out the detailed mechanistic studies and found the involvement of a highly reactive alkylrhodium complex which derived from Et(2)Zn and RhCl(PPh(3))(3) in this alpha-trifluoromethylation. Furthermore, this alpha-trifluoromethylation was applied to other types of carbonyl compounds in good yields.
迄今为止，α-三氟甲基羰基化合物的合成一直被认为是困难的，因为CF(3)(δ-)-I(δ+)的极化与CH(3)(δ+)-I(δ-)相反，这使得将CF(3)(+)单元引入烯醇盐变得困难。我们最近报道了使用Et(2)Zn与Rh催化剂对酮进行有效的α-三氟甲基化反应，但该反应机理尚未完全明确。现在，我们进行了详细的机理研究，发现在该α-三氟甲基化反应中涉及一种由Et(2)Zn和RhCl(PPh(3))(3)衍生的高活性烷基铑配合物。此外，这种α-三氟甲基化反应以良好的产率应用于其他类型的羰基化合物。
