作者:Alenka Tomažič、John B. Hynes
DOI:10.1002/jhet.5570290440
日期:1992.7
Three new 2,4-diaminoquinazolines, the 5,6-difluoro, 6,7-difluoro and 7,8-difluoro isomers were prepared by the reaction of the requisite trifluorobenzonitrile and guanidine carbonate. Surprisingly, 2,3,6-trifluorobenzonitriles gave 2,4-diamino-5,6-difluoroquinazoline exclusively as determined by high resolution nuclear magnetic resonance spectroscopy. On the other hand, 3-amino-2,6-difluorobenzonitrile
通过必要的三氟苄腈和碳酸胍的反应,制备了三种新的2,4-二氨基喹唑啉,即5,6-二氟,6,7-二氟和7,8-二氟异构体。出乎意料的是,由高分辨率核磁共振光谱法测定,仅2,3,6-三氟苄腈给出了2,4-二氨基-5,6-二氟喹唑啉。另一方面,3-氨基-2,6-二氟苄腈与碳酸胍反应仅生成5-氟-2,4,8-三氨基喹唑啉。随后使用Sandmeyer方法将该化合物转化为8-氯-2,4-二氨基-5-氟喹唑啉。2,4-二氨基-8-氟喹唑啉的硝化仅发生在第六位,产生2,4-二氨基-8-氟-6-硝基喹唑啉,将其用氯化亚锡还原后得到8-氟-2,4,6-三氨基喹唑啉。以类似的方式,在6-位对7-氟-2,4-二氨基喹唑啉进行硝化,然后还原得到7-氟-2,4,6-三氨基喹唑啉。最后,将这些三氨基喹唑啉在桑德梅尔条件下均转化为6-氯衍生物,分别得到6-氯-2,4-二氨基-8-氟喹唑啉和6-氯-2,4-二氨基-7-氟喹唑啉。