The title compounds having different substituents on the heterocyclic framework were prepared by several methods from 2-acetamido-3-hydroxypyridine. The condensation of 2-protected-amino-3-hydroxypyridine with 2-chloroacrylonitrile or ethyl 2,3-dibromopropionate provided in several cases two isomeric pyrido-oxazines. Whereas the reaction of 2-acetamido-3-hydroxypyridine with methyl 2,3-dibromopropionate or with α-halocarbonyl compounds gave exclusively the 2-substituted pyrido-oxazine, in a one-step operation.

中文翻译：

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取代的3,4-二氢-2 H-吡啶并[3,2- b ] [1,4]恶嗪的合成作为潜在生物活性化合物的新支架

通过几种方法由2-乙酰氨基-3-羟基吡啶制备在杂环骨架上具有不同取代基的标题化合物。2-保护的氨基-3-羟基吡啶与2-氯丙烯腈或2,3-二溴丙酸乙酯的缩合在几种情况下提供了两种异构的吡啶并恶嗪。而2-乙酰氨基-3-羟基吡啶与2，3-二溴丙酸甲酯或与α-卤代羰基化合物的反应在一步操作中仅得到2-取代的吡啶并恶嗪。