Synthetic Studies toward Bazzanin K: Regioselective and Chemoselective Three-Component Suzuki Coupling.

The terphenyl substructure of the chiral cyclophane natural product bazzanin K was constructed. The key step involved sequential Suzuki couplings of a nonsymmetric dibromobenzene, which can be performed as a two-step process or as a one-pot three-component coupling. The key step represented a regioselective coupling of a dibromobenzene, as well as a chemoselective coupling of phenyl bromides in the presence of phenyl chlorides. Terphenyl intermediates displayed atropdiastereoisomerism, and they were converted to a single phenanthrene target by way of ring-closing metathesis.