Five-Membered Ring Systems: With More than One N Atom

Divergent Reactivity of Nitrocyclopropanes with Huisgen Zwitterions and Facile Syntheses of 3-Alkoxy Pyrazolines and Pyrazoles

“…Among numerous bioactive pyrazolines and pyrazoles, it is noteworthy that a group of 3-oxy­(oxo) analogues possess important and diverse properties including antipyretic, analgesic, fungicidal, and anti-inflammatory activities (Figure ). , Under this circumstance, the development of effective synthetic methods for pyrazolines and pyrazoles has therefore stimulated much interest from chemists. − Traditional approaches such as the condensation of 1,3-dicarbonyl compounds with hydrazines and the [3 + 2] cycloaddition of 1,3-dipoles have proven to be effective; however, alternative and efficient synthetic strategies for structurally diverse pyrazolines and pyrazoles remain highly desirable. Over the past decade, great progress in this aspect has been witnessed. , …”