Cover Image, Volume 50, Issue 18


original image

A deprotonation process at the 4-CH group of a-amino acid N-carboxyanhydride (NCA) in the presence of rare earth metallic tris[bis(trimethylsilyl)amide] ((TMSN)3Ln) is presented by J. Ling, H. Peng, and Z. Shen on page 3743. This long-term neglected reaction shows the acidity of the 4-CH group, not only explaining the racemization phenomenon of NCA in a strong base environment but also supporting that the proposed 4-CH-depronated NCA is responsible for N-substitute NCA polymerization. In addition, (TMSN)3Ln is effective for preparing homo-polypeptides and block co-polypeptides with low molecular weight distributions (generally below 1.3).