Applications of 4-alkynylated pyrazol-3-ones: Synthesis of pyrazol-4-yl furan- and/or thiophene-2-carboxylates

Chemical reactivity and applications of 4-alkynylated pyrazol-3-ones are described. A facile access to the synthesis of novel pyrazol-4-yl furan- and/or thiophene-2-carboxylates through the ring transformation and subsequent acylation of 4-alkynylated pyrazol-3-ones as the key intermediates, which were prepared from pyrazole-4,5-dione and terminal alkynes, in moderate to good yields is achieved. All the synthesized compounds were characterized by spectroscopic analysis.