Reaction of 4-hydroxy-5-oximino-3-thiophenecarboxylates with hydrazines. Formation of pyrazolylthiohydroxamic acids
作者:R. L. Robey、C. A. Alt、E. E. Van Meter
DOI:10.1002/jhet.5570340210
日期:1997.3
The reactions of 4-hydroxy-5-oximino-3-thiophenecarboxylates with hydrazine and substituted hydrazines have been investigated. The products of the reactions have been shown to be pyrazole-3- or 5-thiohydroxamic acids rather than the hydrazones previously described by Benary and Silberstrom. Two alternate mechanisms are proposed which account for the regiochemical outcome. The structures of the pyrazole-3-
Carbon-13 NMR chemical shifts of 1-alkyl-3(5)-cyano-1H-pyrazole-4-carboxylic acid esters
作者:George E. Babbitt、Michael P. Lynch、James R. Beck
DOI:10.1002/mrc.1260280117
日期:1990.1
A compilation of 13C NMR chemical shifts for 13 pairs of 3‐ and 5‐cyano‐substituted pyrazole regioisomers is reported. All of the ring carbon and cyano carbon 13C chemical shifts show a regular, predictable correlation with the particular isomer, whether 3‐cyano or 5‐cyano. These shifts occurred in very narrow ranges, precluding any confusion of assignment within the group of compounds studied. x‐ray