Synthesis and Enzymatic Resolution of C<sup>α</sup>-Dialkylated α-Azido Carboxamides: New Enantiopure α-Azido Acids as Building Blocks in Peptide Synthesis
作者:Norbert Sewald、Micha Jost、Theo Sonke、Bernard Kaptein、Quirinus B. Broxterman
DOI:10.1055/s-2004-834947
日期:——
α-Azido carboxylic acids have recently emerged as versatile N-protected equivalents for α-amino acids, especially valuable when the sterically hindered Cα-dialkylated α-amino acids have to be incorporated. Unsymmetrically substituted Cα-dialkylated α-azido carboxylic acids can be obtained in enantiomerically pure form by enzymatic resolution of α-azido carboxamides. A l-amidase from Ochrobactrum anthropi NCIMB 40321 accepts 2-azido-2,4-dimethylpentanamide as the substrate and provides both the corresponding S-configured α-azido carboxylic acid and the R-configured α-azido carboxamide in excellent enantiomeric purity. The former is a valuable synthetic precursor of α-methylleucine [(α-Me)Leu] in peptide synthesis, as demonstrated by the successful synthesis of a (α-Me)Leu containing efrapeptin C analogue.