Synthesis, antimicrobial and anti-cancer activities of some new N-ethyl, N-benzyl and N-benzoyl-3-indolyl heterocycles.

A series of 1-(N-substituted-1H-indol-3-yl)-3-arylprop-2-ene-1-ones (2a, b-4a, b) were prepared and allowed to react with urea, thiourea or guanidine to give pyrimidine derivatives 5a, b-13a, b. Reaction of 2a, b-4a, b with ethyl acetoacetate in the presence of a base gave cyclohexanone derivatives 14a, b-16a, b. Reaction of the latter compounds with hydrazine hydrate afforded indazole derivatives 17a, b-19a, b. On the other hand, reaction of 2a, b-4a, b with some hydrazine derivatives, namely hydrazine hydrate, acetyl hydrazine, phenylhydrazine and benzylhydrazine hydrochloride, led to the formation of pyrazole derivatives 20a, b-31a, b. Moreover, reaction of 2a, b-4a, b with hydroxylamine hydrochloride gave isoxazole derivatives 32a, b-34a, b. The newly synthesized compounds were tested for their antimicrobial activity and showed that 4-(N-ethyl-1H-indol-3-yl)-6-(p-chlorophenyl)-pyrimidine-2-amine (11b) was the most active of all the test compounds towards Candida albicans compared to the reference drug cycloheximide. Eighteen new compounds, namely pyrimidin-2(1H)-ones 5a, b-7a, b, pyrimidin-2(1H)-thiones 8a, b-10a, b and pyrimidin-2-amines 11a, b-13a, b derivatives, were tested for their in vitro antiproliferative activity against HEPG2, MCF7 and HCT-116 cancer cell lines. 4-(N-ethyl-1H-indol-3-yl)-6-(p-methoxyphenyl)-pyrimidin-2-amine (11a) was found to be highly active with IC(50) of 0.7 μmol L⁻¹.