- Studies on Pyrazines. Part 22. Lewis Acid-Mediated Cyanation of Pyrazine N-Oxides with Trimethylsilyl Cyanide: New Route to 2-Substituted 3-Cyanopyrazines
-
Reaction of 3-substituted pyrazine 1-oxides with trimethylsilyl cyanide in the presence of triethylamine in acetonitrile gave the corresponding cyanopyrazines, yields of which depended remarkably on the substituent.Electron-donating groups enhanced the cyanation with high regioselectivity to 2-substituted 3-cyanopyrazines, while a chloro substituent suppressed the conversion.Addition of zinc halide to the reaction mixture, in most cases, increased the reactivity and improved the regioselectivity.On the other hand, the N-oxides carrying an electron-withdrawing methoxycarbonyl or N-butylcarbamoyl group underwent the cyanation, without need for the Lewis acid, to provide a mixture of nearly equal amounts of 2-substituted 3- and 5-cyanopyrazines.The latter compound was exclusively obtained when 3-methoxycarbonyl- or 3-cyanopyrazine 1-oxide was treated with diethoxyphosphoryl cyanide.
- Sato, Nobuhiro,Shimomura, Yuji,Ohwaki, Yoshie,Takeuchi, Ryo
-
p. 2877 - 2882
(2007/10/02)
-
- Novel 1-(mono-o-substituted benzoyl)-3-(substituted pyrazinyl) ureas
-
Novel 1-(mono-o-substituted benzoyl)-3-(substituted pyrazinyl) ureas, active as insecticides, and methods for their use as insecticides.
- -
-
-