Hydrazinolysis of ethyl 2,5-dioxo-1,5-dihydro-2H-chromeno[2,3-b]- pyridine-3-carboxylate (2) afforded chromeno[2,3-b]pyridine-3-carbohydrazide 3 which utilized as a precursor for building a diversity of heterocyclic compounds at position 3. Condensation of carbohydrazide 3 with 3-formylchromone produced the condensation product 4, while addition of carbohydrazide 3 to phenyl isothiocyanate gave hydrazinecarbothioamide derivative 5 which upon cyclization afforded 3-thiadiazolylchromeno[2,3-b]pyridine-2,5(1H)-dione 6. Condensation of carbohydrazide 3 with some monoelectrophilic reagents namely ethyl chloroformate, carbon disulfide, acetyl chloride and benzoyl chloride and chromone-3-carboxylic acid gave a variety of novel 3-oxadiazolylchromeno-[2,3-b]pyridines 7-10 and 12. Treatment of carbohydrazide 3 with a variety of 1,3-bielectrophiles such as acetylacetone, ethyl acetoacetate and diethyl malonate yielded 3-(pyrazolyl)carbonylchromeno[2,3-b]pyridines 13-15. Finally, reaction of carbohydrazide 3 with ethyl cyanoacetate and (ethoxymethylene)malononitrile afforded heteroannulated chromeno[2``,3``:6`,5`]pyrido[2`,3`-d]pyrazolo[1,5-a]-pyrimidines 17 and 18. Structures of the synthesized products were confirmed based on their analytical and spectral data.

中文翻译：

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新型3-杂芳基色基[2,3-]的合成方法

2,5-dioxo-1,5-dihydro-2 H - chromeno[2,3 - b ]-pyridine-3-carboxylate ( 2 )的肼解得到 chromeno[2,3 - b ]pyridine-3-carbohydrazide 3其用作在3位构建多种杂环化合物的前体。碳酰肼3与3-甲酰基色酮的缩合产生缩合产物4 ，而碳酰肼3与异硫氰酸苯酯的加成得到肼碳硫酰胺衍生物5 ，其在环化后得到3-噻二唑基色酮[ 2,3- b ]吡啶-2,5(1 H )-二酮 6 . 碳酰肼3与一些单亲电试剂，即氯甲酸乙酯、二硫化碳、乙酰氯和苯甲酰氯以及色酮-3-羧酸缩合得到多种新型 3-恶二唑基色基-[2,3- b ] 吡啶7-10和12 。碳酰肼的处理3与各种1,3- bielectrophiles如乙酰丙酮，乙酰乙酸乙酯和丙二酸二乙酯，得到3-（吡唑基）carbonylchromeno [2,3- b ]吡啶化合物13 - 15 。最后，碳酰肼3反应 用氰乙酸乙酯和（乙氧基亚甲基）丙二腈生成杂环化的色诺[2`,3`:6`,5`]吡啶并[2`,3`- d ]吡唑并[1,5- a ]-嘧啶17和18 。基于它们的分析和光谱数据确认合成产物的结构。