Preparation of New Nitrogen-bridged Heterocycles. 11. A New Synthetic Method of Pyrazolo[1,5-<i>a</i>]pyridines from the Alkaline Treatment of 1-[(Acylmethylthio)methyleneamino]pyridinium Salts
作者:Akikazu Kakehi、Suketaka Ito、Masayoshi Ito、Toshiaki Yotsuya、Kenji Nagata
DOI:10.1246/bcsj.58.1432
日期:1985.5
Alkaline treatment of 1-[(acylmethylthio)methyleneamino]pyridinium halides gave unexpectedly 3-acyl- or 3-(acylthio)pyrazolo[1,5-a]pyridine derivatives in 35–87% yields. Some 4,4a-dihydropyrido[1,2-d][1,3,4]thiadiazine intermediates involved in these reactions could be detected by their nmr follows and three related 4a,8-dimethyl derivatives were isolated. Substituent effect and possible mechanisms
1-[(酰基甲硫基)亚甲基氨基]吡啶鎓卤化物的碱处理出人意料地以35-87%的产率得到3-酰基-或3-(酰基硫基)吡唑并[1,5-a]吡啶衍生物。一些参与这些反应的 4,4a-二氢吡啶并 [1,2-d][1,3,4] 噻二嗪中间体可以通过它们的核磁共振检测到,并分离出三种相关的 4a,8-二甲基衍生物。还讨论了替代效应和可能的机制。