Helical Foldamer Containing a Combination of Cyclopentane-1,2-diamine and 2,2-Dimethylmalonic Acid

We have developed new helical oligomers using a combination of (1S,2S)-cyclopentane-1,2-diamine [(S,S)-CPDA] and 2,2-dimethylmalonic acid (DMM) residues as building blocks. In solution, the preferred secondary structure of the (S,S) tetramer 6 was a right-handed (P) helix, and that of the (R,R) tetramer ent-6 was a left-handed (M) helix. In the crystalline state, both 6 and the (S,S) pentamer 7 folded into (P) 11-helices, and ent-6 folded into an (M) 11-helix with hydrogen bonds that were oriented in alternating directions.