Synthesis of linear and cyclic homo-beta-peptides based on a binaphthylic beta-amino acid with only axial chirality

The terminally protected, linear, homo-beta-peptides Boc-[(R)-beta(2,2)-HBin](n)-OMe(n = 2-6) as well as the cyclic homo-beta-peptides c[(R)-beta(2,2)-HBin](3) and c[(S)-beta(2,2)-HBin](4), all derived from the 2',1':1,2;1'',2'':3,4-dinaphtheyclohepta-1,3-diene-6-aminomethyl-6-carboxylic, acid residue beta(2,2)-HBin possessing only axial chirality, have been synthesized in solution by the EDC/AtOH coupling method for chain elongation, and by cyclization of pentafluorophenyl esters. A conformational analysis suggested the concomitant occurrence of different intramolecularly H-bonded forms for the linear oligomers in solution.