Acidity and alkylation of 4‐phenyl‐3,5‐dihydroxypyrazole and its derivatives. C versus O and N alkylation

Gury Zvilichovsky*, Mordechai David

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

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.

Original languageEnglish
Pages (from-to)1307-1310
Number of pages4
JournalJournal of Heterocyclic Chemistry
Volume25
Issue number5
DOIs
StatePublished - 1988

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