TY - JOUR
T1 - Acidity and alkylation of 4‐phenyl‐3,5‐dihydroxypyrazole and its derivatives. C versus O and N alkylation
AU - Zvilichovsky, Gury
AU - David, Mordechai
PY - 1988
Y1 - 1988
N2 - 4‐Phenyl‐3,5‐dihydroxypyrazole is a relatively strong acid, with a pKa of 3.70. The effect of substitution, both in the phenyl ring and on the heterocyclic ring, on the acidity was studied. Electron attracting groups on the phenyl group enhance the acidity. Selective replacement by an alkyl group of one or two of the heterocyclic hydrogens lowers the acidity. Meerwein reagent, as well as methyl iodide bring about alkylation on carbon, whereas diazomethane and diethyl sulfate do not. Michael addition proceeds through both carbon and nitrogen.
AB - 4‐Phenyl‐3,5‐dihydroxypyrazole is a relatively strong acid, with a pKa of 3.70. The effect of substitution, both in the phenyl ring and on the heterocyclic ring, on the acidity was studied. Electron attracting groups on the phenyl group enhance the acidity. Selective replacement by an alkyl group of one or two of the heterocyclic hydrogens lowers the acidity. Meerwein reagent, as well as methyl iodide bring about alkylation on carbon, whereas diazomethane and diethyl sulfate do not. Michael addition proceeds through both carbon and nitrogen.
UR - http://www.scopus.com/inward/record.url?scp=84986472105&partnerID=8YFLogxK
U2 - 10.1002/jhet.5570250507
DO - 10.1002/jhet.5570250507
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AN - SCOPUS:84986472105
SN - 0022-152X
VL - 25
SP - 1307
EP - 1310
JO - Journal of Heterocyclic Chemistry
JF - Journal of Heterocyclic Chemistry
IS - 5
ER -