Divergent Assembly of Functionalized Pyrazolo[1, 5-a]pyridine Derivatives via [3+2] Cyclization of N-Aminopyridinium Salts with Various Unsaturated Hydrocarbons
Xiang Liu , Shaohong Ma , Shi Yan , Xiaotian Shi , Shuting Li , Yanlong Ma , Hua Cao
Chinese Journal of Chemistry ›› 2024, Vol. 42 ›› Issue (24) : 3355 -3361.
Divergent Assembly of Functionalized Pyrazolo[1, 5-a]pyridine Derivatives via [3+2] Cyclization of N-Aminopyridinium Salts with Various Unsaturated Hydrocarbons
Comprehensive Summary:Two reaction modes for metal-free [3 + 2] cyclization of N-aminopyridinium derivatives with β-alkoxyvinyl trifluoromethylketones have been described through selective C—O or C—O/C—C bond cleavage. This strategy can also be extended to the [3 + 2] cyclization of N-aminopyridinium derivatives with enaminones and bromoalkynes. A broad range of N-aminopyridinium, N-aminoquinolinium, and N-aminoisoquinolinium salts are well tolerated, enabling the divergent synthesis of trifluoroacylated, non-substituted, acylated, and brominated pyrazolo[1, 5- a]pyridine derivatives (62 examples).
Synthetic methods / Alkenes / Cyclization / [3+2] Annulation / N-Heterocycles
2024 SIOC, CAS, Shanghai, & WILEY-VCH GmbH
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