Synthesis of Benzofuryl Substituted Unsymmetrical Ureas Under Microwave Irradiation

Abstract

A series of 2-benzofuryl substituted unsymmetrical ureas were synthesized by reactions of benzofuroyl isocyanate, which was prepared from benzofuroyl azide by Curtius rearrangement, with various aromatic amines, 2-amino-5-(benzo-2-furyl)-1,3,4-thiadiazole, and 2-amino-5-aryloxymethylene-1,3, 4-thiadiazoles under microwave irradiation. Compared to conventional methods, this synthesis has the advantages of mild reaction conditions, easy handling, and high yields. The products have been characterized by analytical and spectral (IR and ¹ H NMR) data.

Keywords:

• 1,3,4-thiadiazoles
• curtius rearrangement
• isocyanate
• microwave irradiation (MWI)
• unsymmetrical urea

We are thankful for the financial support from the Foundation of Lanzhou Jiaotong University (No. 06-40611) and the Innovation and Technology Fund of Lanzhou Jiaotong University (No. DXS-2007-007).

Notes

^a Irradiated by microwave at less than 490 W;

^b Heated at 120°;