Synthesis and Solution Conformation of Homo-β-peptides Consisting of N-Mannofuranosyl-3-ulosonic acids
摘要:
The synthesis and solution conformation of homo-oligomers of beta-aminoacids, O-N-mannofuranosyl-3-ulosonic acids, have been studied by NMR, MD simulation, and circular dichroism. These oligomers feature a spirocyclic disubstitution and a N,O-acetal functionality at the P-carbon of the backbone, an unprecedented situation in the realm of beta-peptides. Our study shows that tetramer 10 and hexamer 11 adopt a characteristic secondary structure. In the hexamer 11, NMR investigations coupled with MD simulations suggest the preference for a double C-8 turn forming conformation.
The synthesis of fused furanosyl β-amino esters from protected sugar lactones is described, using the combination of a Wittig type reaction and 1,4-addition of benzylamine on the resulting glycosylidenes. This sequence of reactions afford either N-glycosyl-3-ulosonic acid esters, which are the β-analogues of anomeric sugar α-amino esters, or open-chain sugar β-enamino esters, when a retro-Michael reaction