Abstract 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 ...