An isomerization reaction of 7-aryl-3-formylpyrazolo[1,5- a ]pyrimidines to 5-aroyl-NH-pyrazolo[3,4- b ]pyridines proceeding with high yields in aqueous NaOH under microwave conditions is reported. This unprecedented transformation occurs by adding and eliminating a water molecule via an ANRORC mechanism (adding the nucleophile, ring-opening, and ring-closing) studied using DFT calculations. The product's utility was proved as they have aroyl and NH groups that simple methods and readily available reagents easily modified; likewise, their optical properties were studied, highlighting their high potential as highly emissive modular dyes ( φ F up to 99%). NMR, HRMS, and X-ray diffraction analysis resolved the products' structures., Competing Interests: The authors declare no competing financial interest., (This journal is © The Royal Society of Chemistry.)