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Abstract
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A green electrochemical method was developed for the synthesis of new types of spiro and dispiro pyrimidine derivatives. The electrochemical generation of reactive intermediates from para-nitrophenol (PNP) and their reactions with barbituric acids (BA1-BA3) is a key step in the formation of target products (P1-P3). Our data show that the reactivity of the nucleophile (barbituric acids) plays an important role in the type of product. Accordingly, when barbituric acid (BA1) or thiobarbituric acid (BA2) is used as a nucleophile, dispiro product (P1 or P2) is formed in a convergent paired electrochemical reaction. However, when 1,3-dimethylbarbituric acid (BA3) is used as a nucleophile, due to its higher reactivity than BA1, the final product is an spiro compound that results from the reaction of BA3 with cathodically generated para-nitrosophenol. The highly symmetric dispiro and spiro compounds (P1-P3) have been successfully synthesized in a water/ethanol mixture at the carbon electrode in an undivided cell using the constant current electrolysis method. Also, the antibacterial tests indicated that the products P1-P3 showed good antibacterial performance against gram-positive bacteria (Bacillus cereus and Staphylococcus aureus). In this work, we synthesized a number of new spiro and dispiro pyrimidine compounds (P1-P3) using a convergent paired electrochemical method, by electrolysis of PNP in the presence of barbituric acids (BA1-BA3), under mild and green conditions for the first time.
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