Total Synthesis of Nocarterphenyl A, 2‑Dehydroxymethylnocarterphenyl A and Nocarterphenyl D Produced by Marine <i>Nocardiopsis</i> spp.

We report the divergent total synthesis of marine natural products nocarterphenyl A (1), 2-dehydroxymethylnocarterphenyl A (2), and nocarterphenyl D (3). The thiazole-fused p-terphenyl core was synthesized via Suzuki–Miyaura coupling, and dibrominated precursor 6 was obtained by dibromination of a multisubstituted benzothiazole 7 using NBS/morpholine/HFIP. Nocarterphenyl D (3) was synthesized through palladium-catalyzed dehydrogenation cross-coupling. Biological evaluation revealed that nocarterphenyl A (1) inhibited HCT116 cell proliferation by 71% at 10 μM. Preliminary structure–activity relationships are discussed.