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Keywords:

  • Mannich reactions;
  • Naphtho-aza-crown ethers;
  • Crown ethers;
  • Aza-crown ethers;
  • Calcium chloride;
  • ‘Lariat ethers’

Abstract

New naphtho-aza-crown ethers containing different phenolic side-arms attached through the ortho-position of the phenol have been prepared under solvent-free conditions. The starting macrocyclic naphtho-aza-crown ether 2 was obtained by treatment of naphthalene dicarboxylic acid diester 1 with diethylenetriamine in EtOH at room temperature for two days without stirring in 77% yield (Scheme 1). Phenolic ligands (314) were synthesized by the Mannich reaction of the secondary macrocyclic amine 2 with the substituted phenols using nontoxic and inexpensive CaCl2. This procedure was applied successfully for the synthesis of Mannich bases from simple secondary amines. The CaCl2 powder can be reused up to three times after simple washing with dry acetone.