Microwave Assisted Synthesis and Unusual Coupling of Some Novel Pyrido[3,2-f][1,4]thiazepines
作者:Rasha M. Faty、Mohamed M. Youssef、Ayman M.S. Youssef
DOI:10.3390/molecules16064549
日期:——
3-Amino-3-thioxopropanamide (1) reacted with ethyl acetoacetate to form 6-hydroxy-4-methyl-2-thioxo-2,3-dihydropyridine-3-carboxamide (2), which reacted with α-haloketones 3 to produce 2,3-disubstituted-8-hydroxy-6-methyl-2H,5H-pyrido[3,2-f]-[1,4]thiazepin-5-ones 4a-c. Benzoylation of 4c led to the formation of the dibenzoate derivative 9. Compounds 4a-c could be prepared stepwise through the formation of S-alkylated derivatives 10a-c. Compounds 2, 4a-c, 9 and 10a-c were prepared using microwave as a source of heat, and gave better yields in shorter times than those achieved by traditional methods. Coupling of 4a-c with arenediazonium chlorides proceeded unusually to give the 6-hydroxy-4-methyl-2-(arylazo)thieno[2,3-b]pyridin-3(2H)-one ring contraction products 14. Structures of the newly synthesized compounds were proven by spectral and chemical methods.
3-氨基-3-硫代丙酰胺(1)与乙酰乙酸乙酯反应,生成6-羟基-4-甲基-2-硫代-2,3-二氢吡啶-3-羧酰胺(2),该化合物又与α-卤酮3反应,产生2,3-二取代-8-羟基-6-甲基-2H,5H-吡啶[3,2-f]-[1,4]噻嗪-5-酮类化合物4a-c。4c的苯甲酰化反应生成二苯甲酸酯衍生物9。化合物4a-c可以通过S-烷基化衍生物10a-c的逐步合成制备。化合物2、4a-c、9和10a-c均采用微波加热的方法制备,与传统方法相比,产率更高、时间更短。化合物4a-c与芳基重氮盐氯化物的偶联反应不寻常地生成了6-羟基-4-甲基-2-(芳基偶氮)噻吩[2,3-b]吡啶-3(2H)-酮的环缩合产物14。新合成化合物的结构通过光谱和化学方法得到了验证。