Solid‐state synthesis of cyclo LD‐diphenylalanine: A chiral phase built from achiral subunits
作者:Ariel Pérez‐Mellor、Katia Le Barbu‐Debus、Anne Zehnacker
DOI:10.1002/chir.23195
日期:2020.5
The solid‐state structure of LL/DD or LD/DL diphenylalanine diluted in KBr pellets is studied by infrared (IR) absorption and vibrational circular dichroism (VCD) spectroscopy. The structure depends on the absolute configuration of the residues. The natural LL diphenylalanine exists as a mixture of neutral and zwitterionic structures, depending on the humidity of the sample, while mostly the zwitterion
Water-Tolerant and Atom Economical Amide Bond Formation by Metal-Substituted Polyoxometalate Catalysts
作者:Francisco de Azambuja、Tatjana N. Parac-Vogt
DOI:10.1021/acscatal.9b03415
日期:2019.11.1
A simple, safe, and inexpensive amide bond formation directly from nonactivated carboxylicacids and free amines is presented in this work. Readily available Zr(IV)- and Hf(IV)-substituted polyoxometalates (POM) are shown to be catalysts for the amide bond formationreaction under mild conditions, low catalyst loading, and without the use of water scavengers, dry solvents, additives for facilitating
Peptide bond formation by aminolysin-A catalysis: A simple approach to enzymatic synthesis of diverse short oligopeptides and biologically active puromycins
peptide bonds to give linear homo-oligopeptides, hetero-dipeptides, and cyclicdipeptides using cost-effective substrates in a one-pot reaction. Aminolysin-A can recognize several C-terminal-modified aminoacids, including the L- and D-forms, as acyl donors as well as free amines, including aminoacids and puromycin aminonucleoside, as acyl acceptors. The absence of aminoacid esters prevents the formation