Quinoxalines. Part 12: Synthesis and structural study of 1-(thiazol-2-yl)-1H-pyrazolo[3,4-b]quinoxalines—the dehydrogenative cyclization with hydroxylamine hydrochloride
作者:Gerhard Sarodnick、Matthias Heydenreich、Torsten Linker、Erich Kleinpeter
DOI:10.1016/s0040-4020(03)01024-x
日期:2003.8
Starting with 2-acetylquinoxaline a novel class of heterocyclic compounds, the 1-(thiazol-2-yl)-1H-pyrazolo[3,4-b]quinoxalines 4, were prepared by following two different synthetic procedures: 2-acetylquinoxaline reacted with thiosemicarbazide to the thiosemicarbazones 1a which was (i) cyclized with α-halogeno ketones to the thiazoles 3. These compounds were dehydrogenated in acidic medium to the title
以2-乙酰基喹喔啉为原料,通过以下两种不同的合成方法制备了一类新型的杂环化合物:1-(噻唑-2-基)-1 H-吡唑并[3,4- b ]喹喔啉4:2-乙酰基喹喔啉反应用硫代氨基脲将硫代氨基甲酮1a(a)用α-卤代酮环化成噻唑3。这些化合物在酸性介质中脱氢为标题化合物4。(ii)也可以使用NH 2 OH·HCl将硫代半脲1a脱氢成硫代酰胺5a,最后将它们用α-卤代酮环化成标题化合物4。一锅法仅分离出噻唑3a,将其他噻唑3脱氢。从硫代酰胺5a还获得了化合物9,通过与二溴二乙酰基反应,以及化合物10,通过用乙炔基二羧酸二甲酯处理。两者的分析1 H和13 C NMR谱是不直接的,但可以通过采用一维和二维NMR光谱的整个库终于实现。