DOI: 10.3987/COM-01-9407

Synthesis, 1H and 13C NMR study of pyrazoles derived from chiral cyclohexanones (3-methylcyclohexanone, menthone, pulegone, dihydrocarvone and carvone)

The ¹H and ¹³C chemical shifts of four tetrahydroindazoles (two of them existing as diastereomeric mixtures) and one aldazine were measured and assigned. These compounds were obtained from monoterpenic ketones (R)-(+)-3-methylcyclohexanone, (2S,5R)-(-)-menthone, (R)-(+)-pulegone, (5R)-(+)-dihydrocarvone, and (R)-(-)-carvone in a two-step procedure. The annular tautomerism in CDCl₃solution was calculated and compared with ab initio calculations (B3LYP/6-31G*).