Synthesis and biological activity of some new furan quaternary salts

A series of new N-(5-substituted 2-furfuryl)-N,N-dimethyl-N-aryloxyalkyl quaternary ammonium salts relating to general structure IV has been synthesized by reacting 5-substituted 2-(N,N-dimethylaminomethyl)furans IIa-d with appropriate aryloxyalkyl bromides III. The resulting compounds are tested for in vitro antimicrobial activity. A simpler synthesis of 5-nitro-2-(N,N-dimethylaminomethyl)furan (IId) involving the reduction of N,N-dimethyl-5-nitro-2-furamide (Ib) with diborane is described. A new compound, 5-bromo-2-(N,N-dimethylaminomethyl)furnan (IIc), is prepared in a similar way. Many of these compounds (22, 28, 34, 37-42, 44, and 45) indicate high activity against Staphylococcus aureus, Streptococcus faecalis, Klebsiella pneumoniae, and Pseudomonas aeruginosa and are more active than nitrofurantoin, Compounds 22, 34 and 41 exhibit the highest in vitro antibacterial activity in the series. Some of these quaternary salts (22, 25, 37, 37-41, and 60) possess appreciable activity against Mycobacterium tuberculosis H37Rv. None of these compounds show significant antifungal activity. Eight compounds (18, 21, 22, 26-28, 32, and 34) have high in vitro antibacterial activity were inactive when tested for anthelmintic activity in rats against Nippostrongylus brasiliensis and Hymenolepis nana.