β-Peptoids: synthesis of a novel dimer having a fully extended conformation

Chiral imines 1a,b , already synthesized in our laboratory, were converted in good yield by reduction into the corresponding N -benzyl-γ-lactams 2a,b . Desilylation followed by oxidation of the hydroxymethyl functionality gave the N -benzyl-β-amino acids 5a,b in good yield and high purity. Starting from compound 6a , the corresponding β-peptoid dimer 8 was prepared, together with its derivatives 9 and 10 , these latter displaying conformational restriction about the peptide bond, as evidenced by NMR data.