Anticancer Agents, 15. Squaric Acid Diethyl Ester: A New Coupling Reagent for the Formation of Drug Biopolymer Conjugates. Synthesis of Squaric Acid Ester Amides and Diamides

Lutz F. Tietze, Michael Arlt, Matthias Beller, Karl‐Heinz ‐H Gl üsenkamp, Eckhard Jähde, Manfred F. Rajewsky

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203 Scopus citations

Abstract

Reaction of squaric acid diethyl ester (1) with a slight excess of a primary or secondary amine 2 in ethanol, dichloromethane or aqueous buffer (pH 7) at 20°C for 0.3–12 h gives the squaric acid amide esters 3 in mostly excellent yields. Treatment of 3 with amines 2 or 4 in organic solvents in the presence of triethylamine or in aqueous buffer (pH 9) leads to the corresponding symmetrical and unsymmetrical squaric acid diamides 5, respectively. The reaction can be followed by UV spectroscopy.

Original languageEnglish
Pages (from-to)1215-1221
Number of pages7
JournalChemische Berichte
Volume124
Issue number5
DOIs
StatePublished - 1991
Externally publishedYes

Keywords

  • Anticancer agents
  • Biopolymers
  • Conjugates
  • Coupling reagents
  • Squaric acid
  • diamides of
  • ester amides of

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