1. Synthesis, crystal structure and molecular conformation of Nalpha-Boc-L-leucyl-(Z)-beta-(3-pyridyl)-alpha,beta- dehydroalanyl-L-leucine methyl ester
K Yamada, H Oku, S-S Shinoda, R Katakai J Pept Res. 2005 Feb;65(2):167-74. doi: 10.1111/j.1399-3011.2005.00232.x.
A protected tridehydropeptide containing (Z)-beta-(3-pyridyl)-alpha,beta-dehydroalanine (Delta(Z)3Pal) residue, Boc-Leu-Delta(Z)3Pal-Leu-OMe (1), was synthesized via Erlenmeyer azlactone method. X-ray crystallographic analysis revealed that the peptide 1 adopts an extended conformation, which is similar to that of a Delta(Z)Phe analog, Boc-Leu-Delta(Z)Phe-Leu-OMe (2).
2. Synthesis of 3-(3-pyridyl)- and 3-(3-benzo[b]thienyl)-D-alanine
P N Rao, J E Burdett Jr, J W Cessac, C M DiNunno, D M Peterson, H K Kim Int J Pept Protein Res. 1987 Jan;29(1):118-25. doi: 10.1111/j.1399-3011.1987.tb02237.x.
The DL-arylamino acid ethyl ester derivatives of beta-(3-pyridyl)-DL-alanine, and beta-(3-benzo[b]thienyl)-DL-alanine were synthesized by diethyl acetamidomalonate condensation with the respective arylmethyl halides followed by partial hydrolysis to the monoethyl ester and decarboxylation. Each derivative was enzymatically resolved to a separable mixture of the corresponding N-acetyl-L-amino acid and the unchanged D amino acid derivative. Acidic hydrolysis of the latter gave the corresponding D-amino acid, the optical purity of which was established by HPLC analysis of the 2,3,4,6-tetra-O-acetyl-beta-D-glucopyranosyl isothiocyanate (GITC) derivative. The free D amino acids were converted to D-BOC derivatives by reaction with di-tert-butyldicarbonate in tert-butyl alcohol, water and sodium hydroxide.
