α-Sila-Dipeptides: Synthesis and Characterization.

The first two α-sila-dipeptides, 7 and cyclo-sila-dipeptide 8, were synthesized and characterized by several methods, including X-ray crystallography. Bulky t-BuMe2 Si substituents provide some kinetic stabilization to the synthesized molecules. 7 and 8 are the first examples of a "Si for C switch" in the central α-position of an amino acid or a peptide, in which silicon is bonded to both the amino and the carbonyl groups.