Diastereomeric (η4-diene)Fe(CO)3 complexes containing chiral amide groups: a convenient method for the resolution of amino acids was written by Schumacher, Marc;Coste, Gerald;Miesch, Laurence. And the article was included in Synthesis in 2009.Electric Literature of C12H23NO4 This article mentions the following:
Diastereomeric (η4-N-substituted-hexa-2,4-dienamide)Fe(CO)3 complexes bearing chiral amide groups were used for the resolution of (η4-dienecarboxylic acid)Fe(CO)3 complexes. Using the latter, enantiomerically pure proteinogenic or nonproteinogenic α-amino acids were prepared In the experiment, the researchers used many compounds, for example, Boc-D-Leu-OMe (cas: 133467-01-3Electric Literature of C12H23NO4).
Boc-D-Leu-OMe (cas: 133467-01-3) belongs to esters. Esters typically have a pleasant smell; those of low molecular weight are commonly used as fragrances and are found in essential oils and pheromones. Esters contain a carbonyl center, which gives rise to 120° C–C–O and O–C–O angles. Unlike amides, esters are structurally flexible functional groups because rotation about the C–O–C bonds has a low barrier. Their flexibility and low polarity is manifested in their physical properties; they tend to be less rigid (lower melting point) and more volatile (lower boiling point) than the corresponding amides. Electric Literature of C12H23NO4
Referemce:
Ester – Wikipedia,
Ester – an overview | ScienceDirect Topics