Asymmetric Synthesis of a New Helix‐Forming β‐Amino Acid: trans‐4‐Aminopiperidine‐3‐carboxylic Acid

We report a synthesis of a protected derivative of trans‐4‐aminopiperidine‐3‐carboxylic acid (APiC). The route provides either enantiomer. All intermediates are purified by crystallization, and large‐scale preparation is therefore possible. An analogous route provides either enantiomer of trans‐2‐aminocyclohexanecarboxylic acid (ACHC). We have previously shown that β‐peptide oligomers containing ACHC adopt a helical conformation defined by 14‐membered C=O(i)···H−N(i − 2) hydrogen bonds (“14‐helix”). Here we show that APiC residues can be incorporated into the 14‐helix. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)