Synthesis and antiproliferative evaluation of thiophene-coupled azetidin-3-ylamino quinoline-3-carbonitrile derivatives

A novel series of (substituted)-1-methyl-2-oxo-4-(1-(thiophene-2-carbonyl)azetidin-3-ylamino)-1,2-dihydroquinoline-3-carbonitrile derivatives (5a–5m) was synthesized from substituted 2-aminobenzoic acids (1a–1g) via 1H-benzo[d][1,3]oxazine-2,4-diones (2a–2g). A straightforward route was established for the synthesis of structurally varied quinoline-3-carbonitrile derivatives linked to thiophene-bearing azetidinylamine units through halogenation, cyclization, displacement, SₙAr substitution, amide coupling, and Suzuki coupling. The structures of the final compounds were characterized by 1H NMR, mass spectrometry, and elemental analysis, and their purity was assessed by HPLC. All synthesized compounds were evaluated for antiproliferative activity against A-549, DU-145, HeLa, and MCF-7 cancer cell lines using the MTT assay, with doxorubicin as the positive control. The most active synthesized compounds showed IC50 values of 3.16–11.40 µM. Overall, compounds 5b, 5d, 5l, and 5m showed the most favorable activity profiles across the tested cell-line panel, although they were less potent than doxorubicin. Substitution at the 6- and 7-positions of the quinoline-3-carbonitrile scaffold influenced the observed antiproliferative activity.