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

Abstract

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.