木质素磺酸催化4H-吡啶[1,2-a]嘧啶-4-酮的合成

Lignosulfonic Acid-Catalyzed Synthesis of 4H-pyrido[1,2-a]pyrimidin-4-one derivatives

摘要:

在乙醇作溶剂100 °C条件下反应24 h，木质素磺酸能催化β-酮酯与2-氨基吡啶类化合物通过环化反应合成一系列4H-吡啶[1,2-a]嘧啶-4-酮衍生物，产物经1H NMR 和13C NMR 表征，最高产率可达84%。木质素磺酸催化剂由造纸工业副产物木质素磺酸盐通过酸化得到，在重复使用4次之后，产率能达到75%，催化活性无明显下降，扩大反应的规模到克级，催化效果保持不变。

Abstract:

A series of 4H-pyrido[1,2-a]pyrimidin-4-one derivatives were obtained by lignosulfonic acid-catalyzed annulation of 2-aminopyridines with β-oxo esters under the condition of ethanol as solvent at 100 °C for 24 hours. The structures of products were elucidated by 1H NMR and 13C NMR, and the maximum yield can reach 84%. The lignosulfonic acid catalyst is obtained by acidification of lignosulfonate, a byproduct of the paper-making industry. After 4 repeated uses, the yield can reach 75%, and the catalytic activity does not significantly decrease. The reaction scale is expanded to the gram level, and the catalytic effect remains unchanged.