K. Bougrin et al., CONVERSION OF CIS-PYRAZOLINES AND TRANS-P YRAZOLINES INTO PYRAZOLES ON FERRIC NITRATE OR CUPRIC NITRATE IMPREGNATED MINERAL SUPPORT, Tetrahedron letters, 36(23), 1995, pp. 4065-4068
Pyrazoles are prepared from cis and trans-pyrazolines with good yield
in dichloromethane under mild reaction conditions using the inexpensiv
e clay-supported iron (III) nitrate ''Clayfen'' or copper (II) nitrate
''Claycop''.