SYNTHESIS OF SOME 3(4)-BROMO AND 3, 4-DIALKOXY-5-NITROFURAN AZOMETHINE DERIVATIVES AND THEIR ANTIBACTERIAL ACTIVITIES

Thirty two new compounds of 3(4)-bromo-5-nitrofuran azomethine derivatives were synthesized and their antimicrobial activities investigated.3(4)-Bromo-2-furaldehyde was prepared from 2-furoic acid or furfural respectively by known method, followed by nitration and condensation to afford compounds Ⅰ₂～Ⅰ₈, Ⅱ₂～Ⅱ₈.Condensation of diethyl diglycolate with diethyl oxalate in the presence of sodium methoxide afforded dimethyl 3,4-dihydroxy-2,5-furandicarboxyiate, from which 3,4-dialkoxy-2-furaldehydes were prepared via subsequent O-alkylation, hydrolysis, decarboxylation and Vilsmeier reaction. Nitration of the above aldehydes led to tile corresponding 5-nitrated aldehyde diacetates which were converted to the lille compounds Ⅲ₂～Ⅲ8, Ⅳ₂～Ⅳ₈.Compouds Ⅰ₂～Ⅰ₃, Ⅰ₆～Ⅰ₇, Ⅱ₂～Ⅱ₈ and Ⅲ₁～Ⅲ₈ showed bacterial activities in preliminary pharmacological tests and the 4-bromo compounds are more active than the corresponding 3-bromo-isomers and their parent compounds. Most of 3-brominated, 3,4-dimethoxylated compounds showed less activities than their respective parent drugs. All of 3,4-diethoxylated compounds did not possess antibacterial activities.