Triproline Analogues of Pro-Leu-Gly-NH2 with Pro/Leu and Pro/Phe Chimeric Amino Acids in Position 2

Synthesis of the cis- and trans-isomers of the proline-leucine (3-i-Pr-Pro) and proline-phenylalanine (3-Ph-Pro) chimeric amino acids was accomplished by intramolecular reductive-cycloalkylation of the appropriate azido-olefin. These chimeric amino acids were incorporated into the triprolyl analogues of Pro-Leu-Gly-NH2: Pro-cis-3-i-Pr-Pro-Pro-NH2 (3), Pro-trans-3-i-Pr-Pro-Pro-NH2 (4), Pro-cis-3-Ph-Pro-Pro-NH2 (5), Pro-trans-3-Ph-Pro-Pro-NH2 (6).