New antimicrobial 9-[p-heterocyclo-substituted anilino]-tetrahydroacridines

ABSTRACT

The chemistry of tetrahydroacridines is of continuous interest, as they are associated with pharmacological activities[1-9]. Some members of this class of compounds are used as memory-enhancing agents for treating Alzheimer disease [1, 2] acetylcholine esterase inhibitors[3-5], DNA-binding agents[6], antimicrobial agents[7] and as amoebicides[7-9]. The present work deals with the synthesis of a new series of 9-[p-[4-aryl- 3-cyano-2-iminopyridin-6-yl] anilino]-1, 2, 3, 4-tetrahydroacridines [3] and their 2-oxo-[or thioxo]-pyridinylanilino derivatives 4 and 5, besides other related products 7-12 to be evaluated against bacteria and fungi. Synthesis was achieved by allowing 9-chloro-1, 2, 3, 4-tetrahydroacridine [1][10] to react with p-aminoacetophenone to give the 9-[p-acetylanilino] derivative 2. The one pot reaction of 2 with malononitrile, ammonium acetate and the appropriate aromatic aldehyde afforded the corresponding 9-[p-[4-aryl-3-cyano-2-iminopyridin-6-yl]-anilino]-1, 2, 3, 4-tetrahydroacridines [3a-e], respectively [Route a]. Similarly, reaction of 2 with ethyl cyanoacetate, ammonium acetate and the appropriate aromatic aldehyde in n-butanol afforded the corresponding 9-[p-[4-aryl-3-cyano-2[1H]-oxo-pyridin-6-yl] anilino]-1, 2, 3, 4-tetrahydroacridines [4a-d], respectively. On the other hand, the reaction of an ethanolic mixture of 2 with substituted arylmethylene cyanothioacetanilides [5][11, 12] in the presence of ammonium acetate gave the corresponding 3-cyano-4-arylpyridin-2[1H]-thiones [6a-d], respectively [Route a]. Also reaction of 1 with ethyl-p-aminobenzoate gave the corresponding ethyl-p-[1, 2, 3, 4-tetra-hydroacridin-9-yl] aminobenzoate [7] which upon reaction with hydrazine hydrate afforded the corresponding acid hydrazide 8. [Route b]. In addition, acetylation of 2 was accomplished by heating it with ethyl acetate in the presence of sodium metal to give p-[[1, 2, 3, 4-tetrahydroacridin-9-yl]amino]acetylacetophenone [9]. Bromination of 2 afforded 9-[p-bromo-acetyl anilino]-1, 2, 3, 4-tetrahydroacridine [10] which upon reaction with thiourea gave the corresponding 9-[p-[2-aminothiazol-4-yl]aniline-1, 2, 3, 4-tetrahydroacridine [11] was hydrobromide salt, while reaction of 10 with malononitrile afforded p-[1, 2, 3, 4-tetrahydroacridin-9-yl]amino-benzoylmethyl malononitrile [12] [Route c]