An Efficient ZrCl4 Catalyzed Aza-Michael Addition Reaction: Synthesis of C-Linked Carbo β3-Amino Acids
作者:Krishna Damera、Katta Reddy、Gangavaram Sharma
DOI:10.2174/157017809787582834
日期:2009.3.1
A mild aza-Michael protocol has been developed using ZrCl4 as catalyst on α, β-unsaturated esters and nitriles. The aromatic amines were found to give the products with ease. The ZrCl4 mediated route was compatible with acid sensitive carbohydrate esters and provided an efficient method to prepare C-linked carbo β3-amino acids (β3-Caa).
Synthesis and conformational studies of peptides from new C-linked carbo-β-amino acids (β-Caas) with anomeric methylamino- and difluorophenyl moieties
作者:Gangavaram V. M. Sharma、Velaparthi Subash、Nelli Yella Reddy、Kongari Narsimulu、Rapolu Ravi、Vivekanand B. Jadhav、Upadhyayula S. N. Murthy、Kankipati Hara Kishore、Ajit C. Kunwar
DOI:10.1039/b810817j
日期:——
New C-linked carbo-β-amino acids (β-Caas), Cbz-(S)-β-Caa-(NHBoc)-OMe (1) and Cbz-(R)-β-Caa-(NHBoc)-OMe (2), with an additional amine group (methylamino group of NHBoc) at the C-1 position of the lyxofuranoside side chain and Boc-(S)-β-Caa-(diFP)-OMe (3) and Boc-(R)-β-Caa-(diFP)-OMe (4), with a C-difluorophenyl (diFP) moiety at the anomeric position of the lyxofuranoside side chain were prepared from D-mannose. β-Peptides [tetra- and hexapeptides] were synthesized from these β-Caas, âepimericâ [at the amine stereocentre (Cβ)], using the concept of âalternating chiralityâ to carry out their conformational studies [NMR (CDCl3), CD and MD]. In the monomer design, it was envisaged that the presence of an additional amine group in 1 or 2 would help in solubilizing the peptides in water, while, the C-difluorophenyl (diFP) moiety of 3 and 4 is expected to enhance the biological activity. The peptides having 1 and 2, though could not retain their 12â10-mixed helices in water, have shown moderate activity against Gram positive and Gram negative bacterial strains. The peptides prepared from 3 and 4, much against our expectations, did not display any biological activity.