Angewandte Chemie International Edition
Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Inside Cover: Site-Directed Asymmetric Quaternization of a Peptide Backbone at a C-Terminal Azlactone (Angew. Chem. Int. Ed. 4/2009)
A D2-symmetric chiral tetraaminophosphonium salt functions as an effective phase-transfer catalyst to achieve highly stereoselective alkylation of C-terminal azlactones of growing peptides, as described by T. Ooi and co-workers in their Communication on page 733 ff. The judicious combination of this method with a direct ligation process is a practical strategy for incorporating various chiral, non-racemic α,α-dialkyl-α-amino acids into a specific site of the peptide strand.