Stabilization of 3-Helices in Macrocycles Using Dominant Rotor Methodology.

Stabilization of biologically relevant structural motifs has been a long-standing challenge. Here we show that atropisomeric dominant rotors can stabilize rare 3-helices in macrocycles. The target molecules were prepared using solid-phase peptide synthesis and subjected to extensive structural analysis. Molecular dynamics (MD) simulations enabled us to acquire solution structures for the target molecules, which offered evidence for stable 3-helix formation, ordinarily a metastable state. The 3-helices were shown to retain helicity after heating to 100 °C for 72 h. Moreover, the crude atropisomeric mixtures could be thermally enriched toward 3-helical macrocycles with selectivities of >20:1.