The structure of indazolinone and derivatives in the solid state and in solution: an X-ray and nuclear magnetic resonance study

Trifluoro‐3‐hydroxy‐1H‐indazolecarboxylic Acids and Esters from Perfluorinated Benzenedicarboxylic Acids

“…15 N NMR spectroscopic data (Table 1, data for 2 , 5 and 8 have not been recorded), obtained by 1 H– 15 N 2D inverse proton heteronuclear shift correlation experiments in [D 8 ]THF at 207 K (no correlations were detected at room temperature), again indicate that these derivatives exist as 3‐hydroxy‐1 H ‐indazoles 1b,20,21. The abnormally high N‐1 chemical shift value for 4,5,6‐trifluoro‐3‐hydroxy‐1 H ‐indazole‐7‐carboxylic acid ( 10 ) and its two esters ( 11 and 12 ) is explained by the presence of the intramolecular hydrogen bond shown above in Figure 1.…”

Five‐Membered Heterocycles: 1,2‐Azoles. Part 1. Pyrazoles

“…Pyrazolin-4-ones exist as 4-hydroxypyrazoles and are much less common [4][5][6]8], although deserving attention for their biological potentialities. Indazolones exist as such and not as 3-hydroxyindazoles [343]. The chemistry of pyrazolidinones has been reviewed [344].…”

The Structures of Indazolin‐3‐one (=1,2‐Dihydro‐3H‐indazol‐3‐one) and 7‐Nitroindazolin‐3‐one

“…In Table 2, the experimental results concerning indazolinone 1 are given. The chemical shifts of 1 were reported previously [1]. In the solid state, they correspond to tautomer 1a whose structure was determined by X-ray crystallography.…”

“…Using two solvents, we succeeded in obtaining pure polymorph I (in EtOH) and polymorph II (in AcOEt). The NMR chemical shifts of the solid compound we described in our 1986 paper (see Table 2) correspond to polymorph I (it was obtained from a MeOH solution) [1].…”

“…The square correlation coefficients R 2 for calculated 1b and 1c are 0.975 and 0.952 (the same for both polymorphs). In (D 6 )DMSO solution, we estimated that 85% of 1b and 15% of 1a are present using model compounds as fixed tautomers (replacing NH and OH by MeN and MeO) [1]. Now with the calculated values of Table 1, the best fit was obtained for 80% of 1b and 20% of 1a (n ¼ 10,…”