Regioselective Reduction of 3-Substituted <i>N</i>-Acylpyrazinium Salts toward the Synthesis of 1,2-Dihydropyrazines
作者:Alfred L. Williams、Valentine R. St. Hilaire、Tina Lee
DOI:10.1021/jo202498r
日期:2012.4.20
The regioselective reduction of 3-substituted N-acylpyrazinium salts with n-Bu3SnH 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
的3-取代的区域选择性还原Ñ -acylpyrazinium盐与Ñ -Bu 3 SNH已经开发了的3-取代的1,2- dihydropyrazines在56-94%的收率的合成。吡嗪鎓盐被供电子基团取代有利于1,2-异构体的形成,因为它们比1,6-异构体具有更好的稳定性。在温和酸性条件下,3-甲氧基取代的1,2-二氢吡嗪很容易在良好的收率水解为Δ 5 -2-氧代哌嗪。