Department of Pharmaceutical Sciences, North Carolina Central University, Durham, North Carolina 27707, USA.
J Org Chem. 2012 Apr 20;77(8):4097-102. doi: 10.1021/jo202498r. Epub 2012 Apr 2.
The regioselective reduction of 3-substituted N-acylpyrazinium salts with n-Bu(3)SnH has been developed for the synthesis of 3-substituted 1,2-dihydropyrazines in yields of 56-94%. Substitution of the pyrazinium salts with electron-donating groups favors the formation of the 1,2-isomers as a result of their better stability over the 1,6-isomers. Under mild acidic conditions, 3-methoxy substituted 1,2-dihydropyrazine was easily hydrolyzed in excellent yield to Δ(5)-2-oxopiperazine.
已开发出用正丁基锡氢（n-Bu(3)SnH）对 3-取代 N-酰基吡嗪鎓盐进行区域选择性还原的方法，用于合成产率为 56-94%的 3-取代 1,2-二氢吡嗪。由于电子供体取代的吡嗪鎓盐比 1,6-异构体更稳定，因此有利于形成 1,2-异构体。在温和的酸性条件下，3-甲氧基取代的 1,2-二氢吡嗪很容易以优异的收率水解得到 Δ(5)-2-氧代哌嗪。
