A New Approach to the Synthesis of Heteroannulated 3,1-Oxazin-4-ones from β-Enamino Esters and Phosgeneiminium Salts
作者:Zhijun Wang、Richard Neidlein、Claus Krieger
DOI:10.1055/s-2000-6249
日期:——
The heterocyclic β-enamino ester, ethyl 3,4-diamino-6-(dimethylamino)thieno[2,3-d]pyrimidine-2-carboxylate (3) was reacted with phosgeneiminium salts 6a,b to yield 4H-pyrimido[5′,4′:4,5]thieno[3,2-d][1,3]oxazin-4-ones 7a,b, respectively. Similarly, the reaction of dichloromethylene dimethylammonium chloride 6a with o-aminothiophenecarboxylates 8 and 10 afforded the thienoxazinones 9 and 11. In the case of the o-aminopyrazolecarboxylate 12, the pyrazoloxazinone 13a was formed in low yield, while the ureidopyrazole 13b was the main product. Reaction of 6a with o-aminopyrazinecarboxylate 14 or o-aminoisoxazolecarboxylate 16 did not afford any bicyclic oxazinones were produced with 6a. Instead, the monocyclic products 15 and 17 were obtained.
杂环β-烯氨基酯,乙基3,4-二氨基-6-(二甲氨基)噻吩并[2,3-d]嘧啶-2-羧酸酯(3) 与光气亚胺盐6a,b 反应生成4H-嘧啶基[5 ',4':4,5]噻吩并[3,2-d][1,3]恶嗪-4-酮分别为7a、b。类似地,二氯亚甲基二甲基氯化铵6a与邻氨基噻吩甲酸酯8和10反应得到噻吩嗪酮9和11。在邻氨基吡唑甲酸酯12的情况下,以低产率形成吡唑并恶嗪酮13a,而脲基吡唑13b是主要产物。 6a与邻氨基吡嗪羧酸酯14或邻氨基异恶唑羧酸酯16的反应没有产生由6a产生的任何双环恶嗪酮。相反,得到单环产物15和17。