Tautomerism of hydroxychromenopyrazoles

► Annular tautomerism of hydroxychromenopyrazoles. ► Experimental NMR-spectroscopy of 4,4-dimethyl-7-pentyl-2,4-dihydrochromeno[4,3-c]pyrazol-9-ol. ► B3LYP/6-311++G(d,p) theoretical calculations of 4,4-dimethyl-7-pentyl-2,4-dihydrochromeno[4,3-c]pyrazol-9-ol. ► 4,4-dimethyl-7-pentyl-2,4-dihydrochromeno[4,3-c]pyrazol-9-ol exists mainly as an OH⋯N tautomer in solution.