The present invention relates to macrocyclic compounds of formula (Ia) that are useful as inhibitors of the hepatitis C virus (HCV) NS3 protease, their synthesis, and their use for treating or preventing HCV infections.
Synthesis of α-CF3 carbonylcompounds has been recognized to be difficult up to now because the polarization of CF3δ−-Iδ+ is opposite to that of CH3δ+-Iδ−, and this makes it difficult to introduce CF3+ unit to enolates. We recently reported an effective α-trifluoromethylation of ketones by using Et2Zn with Rh catalyst, but the mechanism has not fully been cleared. Now, we carried out the detailed mechanistic
The treatment of silylenolethers of ketones with CF3–I and Et2Zn in the presence of RhCl(PPh3)3 in DME gave α-trifluoromethyl ketones in good yields. The reaction can be widely applicable to silylenolethers derived from aliphatic or aromatic ketones. In the absence of the rhodium catalyst, the reaction was very slow and the yields were quite poor.
[reaction: see text] The radical trifluoromethylation of ketonesilylenolethers gave alpha-CF(3) ketones in good yields with wide scope of the ketonic substrates including acyclic ketones and cyclopentanone. The use of dialkylzinc to activate the silylenolethers is the key to the efficient radical trifluoromethylation.
Radical Trifluoromethylation of Titanium Ate Enolate
作者:Yoshimitsu Itoh、Koichi Mikami
DOI:10.1021/ol047565a
日期:2005.2.1
The radical trifluoromethylation of ketone titaniumateenolates gave alpha-CF3 ketones in good yields. The use of excess amount of LDA and Ti(OiPr)4 in the preparation of titaniumateenolates is the key to the efficient radical trifluoromethylation. [reaction: see text]