A Convenient Synthesis of 7-Aryl-2,4-dimethoxy-5-oxo-5<i>H</i>-pyrano[4,3-<i>d</i>]pyrimidines
作者:Akimori Wada、Takeshi Nakagawa、Shōichi Kanatomo
DOI:10.1055/s-1989-27240
日期:——
A convenient synthesis of 7-aryl-2,4-dimethoxy-5-oxo-5H-pyrano[4,3-d]pyrimidines 6 is described. The lithium salt of methyl 2,4-dimethoxy-6-methyl-5-pyrimidinecarboxylate (2) reacts smoothly with aromatic aldehydes to afford cycloaddition products 4 in good yields. When 4 is treated with N-bromosuccinimide, aromatization occurs to give 5-oxo-5H-pyrano[4,3-d]pyrimidines 6 via dehydrobromination from the 8-bromo derivatives 5 in satisfactory yields.
本文介绍了一种简便的 7-芳基-2,4-二甲氧基-5-氧代-5H-吡喃并[4,3-d]嘧啶 6 的合成方法。2,4-二甲氧基-6-甲基-5-嘧啶羧酸甲酯(2)的锂盐与芳香醛顺利反应,生成环化产物 4,收率良好。当 4 与 N-溴代琥珀酰亚胺一起处理时,会发生芳香化反应,通过 8-溴衍生物 5 的脱氢溴化得到 5-氧代-5H-吡喃并[4,3-d]嘧啶 6,收率令人满意。