BETA-PEPTIDES - OLIGO-BETA-HOMOALANINES - THE AMIDE ANALOGS OF POLY(3-HYDROXYBUTANOATE)

The linear oligo-beta-peptides derived from beta-homoalanine (H-beta-H Ala-OH) have been prepared by Arndt-Eistert homologation of Boc-alanin e and subsequent peptide coupling procedures. Cyclisation via pentaflu orophenyl esters resulted in the formation of the cyclic beta-peptides in remarkably high yields. The X-ray crystal structure analysis of Bo c-(beta-HAla)(2)-OBn is presented. The cyclic derivatives were found t o be highly insoluble (m.p. > 300 degrees C with decomposition) and th e effect of lithium salts on their solubility, particularly with respe ct to obtaining NMR data, is discussed. The CD spectra of the cyclo-be ta-tetrapeptides are presented and these give an indication that ''nan otube-like'' structures may be present.