Expedient Access to Alkyne‐Tethered <i>N</i> ‐Acyl Pyrazolines and Pyrazoles From Hydrazides and Skipped Diynones

ABSTRACT A convenient, catalyst‐free protocol for the synthesis of hitherto unknown alkyne‐tethered N ‐acyl pyrazolines from readily available hydrazides and skipped diynones has been developed. The subsequent acid‐catalyzed dehydration of the synthesized hydroxy derivatives opened a shortcut toward a representative set of 5‐alkynyl‐1‐acylpyrazoles. The elaborated approaches possess competitive advantages such as complete chemo‐ and regioselectivity, availability of starting materials and excellent yields (up to quantitative) of target products having rich functionality patterns for further derivatization.