Synthesis and conformational investigation of tetrapeptide analogues of the fragment B23-B26 of insulin
摘要:
Tetrapeptides containing one of a set of four different alpha,alpha-dialkyl glycines at the C-terminus were synthesized by conventional methods in solution and their conformational. behavior investigated by H-1 NMR spectroscopy in connection with molecular mechanics calculations. The results were consistent with conformations stabilized by a gamma-turn in the case of compounds with alkyl groups larger than methyl, while the corresponding Aib derivative did not exhibit intramolecular hydrogen bonding. (C) 2004 Elsevier Ltd. All rights reserved.
Facile Synthesis of α,α-Diisobutylglycine and Anchoring Its Derivatives onto PAL-PEG-PS Resin
摘要:
alpha,alpha-Diisobutylglycine has been synthesized using a Pd-mediated dialkylation of ethyl nitroacetate as a key first step. The free alphaalphaAA is N-alpha-protected and has been applied to the assembly of conformationally constrained peptide analogues. Mixed anhydrides from BOP-Cl and Fmoc-alphaalphaAA-OH are used for anchoring alphaalphaAAs onto a trialkoxybenzyl linker on PEG-PS grafted support, upon which a beta-strand mimic with difficult sequence is assembled in a superior quality.