Amino acids and peptides. Part 49. 2-Amino-4-(3-pyridyl)butyric acid and related peptides

The new α-amino acid, 2-amino-4-(3-pyridyl)butyric acid (4)[abbreviation, Ala(3 Pm)], has been synthesized and resolved. The N-t-butoxycarbonyl derivative of the L-amino-acid has been used in the picolyl ester ‘handle’ method to synthesize Boc-Ala(3 Pm)-Ala-Ala-Ala-Lys(Z)-OPic (8)(Pit = 4-picolyl) and its N-acetyl analogue (9), Boc-Ala(3 Pm)-Ala-Ala-D-Ala-Lys(Z)-OPic (10), and Boc-Ala(3 Pm)-Ala-Ala-Val-Lys(Z)-OPic (11). Compounds (8), (9), and (11) are weak inhibitors of human leucocytic elastase.