Carboxylic a-amino

The most commonly used reactions that employ Rh[(5,5)-Et-DuPHOS](cod) X complexes involve the enantioselective hydrogenation of a-(/V-acyl)enamide carboxylates. a-Amino acids are obtained in quantitative yield with high optical purity (95-99% ee) (eq 3). ... 

Enzymatically formed peptides contain a number of structural elements not present in ribosomally formed peptides (16). In addition to a carboxyl a amino(imino) group linkages, these structures may contain carboxyl-groups located in 2, 3-,4-. or 5-position, 2-amino groups, not on y pept ide but ester bonds, and linkages to compounds like carboxylic acids or amines. The list of possible post translational modifications exceeds the respective list for ribosomal peptides. Most prominent are the various modes of cyclizatioti. 

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