【摘要】 本文探索并发现了4H-1,2-噁嗪类化合物合成的新方法,在中性环境下,以溴代丙酮酸肟与Zn/Cu(OAc)2体系作用产生亚硝基乙烯类化合物,再进一步与带有给电子基团的乙烯类化合物进行杂DA环加成反应来合成4H-1,2-噁嗪类化合物,突破了4H-1,2-噁嗪类化合物的合成必须使用碱性环境下这一传统限制条件。首次合成了乙基4,4a,5,6,8a-五氢-苯[e]-1,2-噁嗪-3-羧酸酯(4a),并通过了1HNMR,13C-NMR,IR和元素分析等光谱学的结构表证,另外研究发现乙基4,4a,5,6,7,8a-六氢-1,2-噁嗪吡喃-3-羧酸酯(4c)的合成,采用Zn/Cu(OAc)2体系作为缚酸剂收率(60%)高于使用无水Na2CO3的传统方法(收率50%)。更多还原

【Abstract】 A new approach in neutral medium to synthesize 4H-1,2-oxazine ring was developed.The ethyl 2-nitrosoacrylate was generated by the reaction of ethyl bromopyruvate oxime with Zn/Cu(OAc)2 system,which could react in situ with cyclohexadienes to produce the bicyclic 1,2-oxazines 3-ethoxycarbonyl-4,4a,5,6,8a-pantahydro-1,2-benzoxazine(4a) and known compounds 4b,4c respectively.The structure of the compound 4a was determined by1HNMR,13C-NMR,IR and elemental analysis.The reaction yield of the product 4c could reach 60% when the Zn/Cu(OAc)2 system was used to take the place of the traditional alkali(50% yield only) as dehydrobromination reagent.更多还原