Expeditious synthesis and single crystal structure of new pyrazole-fused 1,4-oxazine

Article abstract of DOI:10.1002/jhet.833

A series of 2,6-diphenyl-4H-pyrazolo[5,1-c][1,4]oxazin-4-ones has been synthesized via a lactonization of 1-(2-oxo-2-phenylethyl)-3-phenyl-1H-pyrazole- 5-carboxylic acids in the presence of Ac₂O at reflux temperature. The products were isolated by simple filtration in excellent yields and were characterized by IR, ¹H-NMR, and HRMS. The molecular structure was confirmed by the X-ray crystal analysis of one compound that was prone to crystallization.