One‐Pot Synthesis of Pyrazoles from Sulfonyl Hydrazides and Alkynyl Ketones Using Environmentally Benign Sulfonium Iodate (I) Reagent

Abstract Pyrazole is an omnipresent moiety in many natural products and pharmaceutically active compounds. Here, we have developed a simple and dynamic method for one‐pot synthesis of substituted pyrazoles through the intramolecular cyclization of hydrazides and alkynyl ketones, using a novel sulfonium saltbased iodate (І) reagent system. This method has the advantage that it proceeds in a one‐pot, without isolating a less stable hydrazone intermediate. Hypervalent iodine‐based reagents are an environmentally benign and greener option to toxic metal oxidants; they have an extensive application in metal‐catalyst‐free reactions, and this reaction proceeds in less time with high yields.