Solvent-Free Synthesis of 2-Amino-5-Aryloxymenthyl1-1,3,4-Thiadiazoles and Their Coumarin or Benzofuran Bis-Heterocyclic Dericatives

2-amino-5-aryloxymethyl-1,3,4-thiadiazoles were synthesized rapidly by a microwave-accelerated solvent-free procedure in high yield via the condensation of thiosemicarbazide with aryloxyacetic acids using poly(ethylene glycol) supported dichlorophosphate as a dehydration reagent. The solvent-free N-acylation of 2-amino-5-aryloxymethyl-1,3,4-thiadiazoles with coumarin-3-carboxylic acid chloride or benzofuran-2-carboxylic acid chloride efficiently afforded corresponding bis-heterocyclic derivatives, 2-(coumarin-3-carboxamido)-5-aryloxymethyl-1,3,4-thiadiazoles, and 2-(benzofuran-2-carboxamido)-5-aryloxymethyl-1,3,4-thiadiazoles. The strategy has advantages of no organic solvent pollution, an elevated reaction rate, an improved yield, and a simple work-up procedure.

Keywords:

• 1,3,4-thiadiazoles
• polymer-supported reagent
• microwave irradiation
• solvent-free
• room temperature grinding

The authors thank the Scientific and Technological Innovation Engineering of Northwest Normal University (NWNU-KJCXGC-02-08) for financial support of this work.

Notes

^a Yields refer to the isolated products.