Conformationally restricted diamines as spacers for parallel β-sheet formation

Article abstract of DOI:10.1016/S0040-4020(97)10191-0

The dibenzofuran-based diamide 4,6-bis(N-acyl-aminomethyl)dibenzofuran is shown by ¹H NMR and IR to have favourable geometry for intramolecular hydrogen bonding. The corresponding dibenzothiophene-based diamide 4,6-bis(N-acyl-aminomethyl)dibenzothiophene does not fulfill the geometric requirements for intramolecular hydrogen bonding. The intramolecularly hydrogen bonded state of the dibenzofuran-based diamide la is found to be 1 ± 0.5 kcal/mol more favoured enthalpically and 4 ± 2 cal/(K·mol) disfavoured entropically than the non-hydrogen bonded state.