In 2022,Jia, Kai; Ma, Wenchao; Yan, Yintao; Zhang, Chenming; Jiang, Chao published an article in Synlett. The title of the article was 《A Mild and Efficient Synthesis of Pyrazolo[1,5-a]pyridines Mediated by Triphenylphosphine/Diiodine》.Application In Synthesis of 2-Bromo-5-methylpyridine The author mentioned the following in the article:
A synthesis of 2,3-diaryl-substituted pyrazolo[1,5-a]pyridines in moderate to good yields under metal-free and mild conditions was described. The intramol. cyclization of the oxime substrates was mediated by PPh3/I2, which led directly to pyrazolo[1,5-a]pyridines without the formation of a 2H-azirine intermediate. Various substituents on the aryl rings were compatible with the method.2-Bromo-5-methylpyridine(cas: 3510-66-5Application In Synthesis of 2-Bromo-5-methylpyridine) was used in this study.
2-Bromo-5-methylpyridine(cas: 3510-66-5) belongs to pyridine. Pyridine is very deactivated towards electrophilic substitution with respect to benzene. For this reason classical formylation, using methods such as the Gattermann or Vilsmeier reactions, are not generally successful. Application In Synthesis of 2-Bromo-5-methylpyridine