Facile Synthesis of Novel 3-(4-phenylisothiazol-5-yl)-2H-chromen-2-one Derivatives as Potential Anticancer Agents

A series of 3-(4-phenylisothiazol-5-yl)-2H-chromen-2-one (6a-l) derivatives has been efficiently synthesized by straightforward sequential reactions. Tandem Vilsmeier Hack reaction/cyclization/bromination/Suzuki cross-coupling reactions were successfully applied to the preparation of title compounds in good-to-high yields. In the synthetic sequences, 3-chloro-3-(2-oxo-2H-chromen-3-yl)acrylaldehydes (2) were found to react with ammonium thiocyanate to yield the corresponding 3-(isothiazol-5-yl)-2H-chromen-2-ones (3). These derivatives were brominated with N-bromo succinamide to yield the corresponding regioselective 3-(4-bromoisothiazol-5-yl)-2H-chromen-2-one (4). Finally, compound 4 was treated with various phenyl/pyrazole/7H-pyrrolo[2,3-d]pyrimidinyl boronic acids 5a-l in the presence of K2CO3 and Pd catalyst in dimethylformamide to yield the corresponding title derivatives 6a-l. All the synthesized compounds were characterized by analytical and spectral studies. All the final compounds were screened against different cancer cell lines (A549, PC3, SKOV3, and B16F10), and among these compounds, 6b, 6g, 6h, and 6l displayed moderate cytotoxic activity against the tested cell lines.