Scope and limitations in the regioselective synthesis of 1,3,5-trisubstituted pyrazoles from beta-amino enones and hydrazine derivatives. (13)c-chemical shift prediction rules for 1,3,5-trtsubstituted pyrazoles.

beta -amino enones react with hydrazine derivatives to give regioselectivel y 1,3,5-trisubstituted pyrazoles. The synthetic method only presents limita tions when the beta -substituent of the enone and the hydrazine substituent are bulky or possess an electron withdrawing character. Comparison of the C-13-NMR spectra of the seventy pyrazoles allowed us to estimate a C-13-che mical shift prediction rule for 1,3,5-trisubstituted pyrazoles, with deviat ions of less than +/- 1 ppm.