The artificial binaphthyl amino acid 6-amino-6′-carboxyethyl-2-methoxy-2′-hydroxy-1,1′-binaphthyl (Bna): synthesis and assembly of Bna peptides

Abstract

The new binaphthyl-based amino acid 6-amino-6′-carboxyethyl-2-methoxy-2′-hydroxy-1,1′-binaphthyl (Bna) is presented, which combines the axially chiral binaphthyl core, a phenolic OH-group as well as terminating amino and carboxyl groups in one structure. The large aromatic rings of the compound provide molecular spacing and π-surface attraction in assembled Bna oligoamides. The synthesis of Bna derivatives is reported, both with the ( R )- and with the ( S )-binaphthyl skeleton. Several dipeptides of ( R )- or ( S )-Bna units combined with natural amino acids, were prepared as ‘building blocks’ for the synthesis of extended Bna peptides. The tetrapeptide Boc-( S )-Val-( S )-Bna(OH)-( S )-Val-( S )-Bna(OPiv)- O - n -But ( 12 ) and the pentapeptide Boc-( S )-Val-( S )-Bna(OH)-( S )-Val-( S )-Bna(OH)-Gly-OH ( 13 ) were prepared via conventional solution phase synthesis and solid phase synthetic techniques, respectively. Compound 12 shows an interesting dynamic 1 H NMR spectrum suggesting compact and aggregated forms in dichloromethane. Compound 13 accelerates the enolisation of acetone. The use of more complex Bna peptides as organo catalysts is proposed.