A multinuclear NMR study (H-1, C-13, N-15) OF 1-monosubstituted pyrazoles

Abstract

The chemical shifts and coupling constants of twenty-three pyrazoles bearing different substituents at position 1 have been studied by H-1, C-13 and N-15 NMR spectroscopy in solution. Three new pyrazoles (N'-pyrazolyl-P,P,P-triphenylphospha-lambda(5)-azene, sodium 1-hydroxypyrazolate and 1-trifluoromethanesulfonylpyrazole) have been prepared; moreover, to assign the signals of some compounds, two other pyrazoles have been synthesized labelled in both nitrogen atoms with N-15 (l-benzyl and 1-hydroxypyrazole). The tautomerism of 1-hydroxypyrazole has been reexamined.