Synthesis of Five Membered Heterocycles  Using Microwaves Technique

Moayed S. AL. Gawady

doi:10.33899/rjs.2010.36830

Abstract

A series of N-(5-substituted 1,3,4–thiadiazol-2-yl maleimides (14-18) were prepared by cyclization of corresponding maleamic acids (7-12).These acids were prepared by the reaction of 2-amino-5-aryloxymethyl–1,3,4–thiadiazoles (1-6) with maleic anhydride. The starting amines (1-6) were prepared from different aryloxyacetic acids and thiosemicarbazide . The structure of the prepared compounds was suggested in the light of IR and UV Spectroscopy.

Highlights

Several procedures were reported for the synthesis of 2-amino-1,3,4-thiadiazoles, in many of these methods a thiosemicarbazide was the starting material which first acylated to 1acylthiosemicarbazide (Saied, 1983) which cyclized with a suitable dehydrating agents such as phosphorus pentachloride (Rabjohn et al, 1973 and Kulchitskaya et al, 1956), phosphorous oxychloride and thionyl chloride (Rabjohn et al, 1973 and Kretov et al, 1956)
Acylation and cyclization could be achieved in a one step reaction by heating an acyl halide, or even a carboxylic acid with a thiosemicarbazide in the presence of phosphorous acid or concentrated sulfuric acid (Saied, 1983)
These heterocyclic amines were used as synthon in synthesis of cyclic amides by their reaction with cyclic anhydrides via intermediate maleamic acid (Rabjohn et al, 1973 )

Summary

Introduction

Several procedures were reported for the synthesis of 2-amino-1,3,4-thiadiazoles, in many of these methods a thiosemicarbazide was the starting material which first acylated to 1acylthiosemicarbazide (Saied, 1983) which cyclized with a suitable dehydrating agents such as phosphorus pentachloride (Rabjohn et al, 1973 and Kulchitskaya et al, 1956), phosphorous oxychloride and thionyl chloride (Rabjohn et al, 1973 and Kretov et al, 1956). ‫ تم إقتراح‬.‫فقد حضرت من تفاعل عدد من مركبات الاريلوكسى حامض الخليك مع الثايوسيمى كاربازيد‬ 2-Amino-5-aryloxymethyl – 1,3,4 –thiadiazoles (1-6 ): Method (a) (conventional procedure): (Saied, 1983)

Results

Conclusion