Methods of Non-a-Amino Acid Synthesis, 2nd Edition

129Biologically Important Amino Acids

6.1.3 as Residues in cyclic PePtides

Cyclic peptides are an interesting and increasingly important class of compounds.

Non-α-amino acid residues play a prominent role in many of these compounds, both

natural products and synthetic analogs. 5-Aminopentanoic acid was used as a linker

for the cyclization of β-dipeptides, for example. Coupling of dipeptide 31, prepared

from β-alanine (3-aminopropanoic acid), with the tert-butyl ester of 5-aminopenta-

noic acid gave an 81% yield of 32.

62

Subsequent deprotection and cyclization gave 33

in 35% overall yield from 32.

BocHN N

H

OH

BocHN

N

H

N

H

HN N

H

N

H

O O

O O

OH

O

O

O

O

31

32

33

H