Synthesis and Structure of 1,4-Dipiperazino Benzenes:  Chiral Terphenyl-type Peptide Helix Mimetics

The terphenyl structure has been proven to be an ideal scaffold mimicking side-chain functionalities of peptidic α-helices. The synthesis of 1,4-dipiperazino benzenes, using stepwise transition metal-catalyzed N-arylation of chiral piperazines to a central benzene core is reported. The structure determination by X-ray crystallography reveals a geometrical arrangement of the hydrophobic side chains resembling the orientation of key i, i + 3, and i + 7 positions in a peptidic α-helix or in terphenyl helix mimetics.