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.

Introduction of Trifluoroethylamine as Amide Isostere by C-H Functionalization of Heteroarenes.

A direct and efficient introduction of a trifluoroethylamine motif into various heteroaromatic structures, using a readily available xanthate S-[1-(N-acetylamino)-2,2,2-trifluoroethyl]-O-ethyl dithiocarbonate (5), is reported. Medicinally relevant trifluoroethylaminated heteroarenes containing a wide range of functional groups were successfully synthesized under mild conditions. This amide isostere could be introduced into both electron-rich and -poor heteroarenes to give the desired products in one step. The beneficial effect of camphorsulfonic acid (CSA) was also demonstrated with electron-deficient heteroarenes.