Synthesis and structural study of novel dimethylcyclobutyl β-peptides

The synthesis of some representative compounds of a new class of cyclobutane-containing β-peptides starting from (−)-verbenone as a chiral precursor is presented. In these products, the cyclobutane moiety is not a part of the peptide backbone but a bulky substituent at the β3-position. These compounds have been carefully characterized and studied on the basis of the combined use of several experimental techniques together with molecular modeling by means of theoretical calculations. In the solid state, the non-cyclic β-peptides adopt a hairpin-like molecular folding ruled by intermolecular hydrogen bonds in the crystal packing.