Improved synthetic access to the β,γ-enol ether amino acids, L-2-amino-4-methoxy-trans-but-3-enoic acid and 1-2-amino-4-methoxy-cis-but-3-enoic acid

Article abstract of DOI:10.1016/S0040-4039(00)98044-4

A synthetic route to L-2-amino-4-methoxy-trans-but-3-enoic acid, exclusive of the cis-isomer, has been developed. The key step is direct formation of a trans-enol ether derivative from the corresponding dimethylacetal, by refluxing in CCl₄, in the presence of hexamethyldisilazane and Me₃SiI. The isomeric L-_cis amino acid could be accessed from this route by isomerizing the intermediate, methyl DL-2-acetamido-2-amino-4-methoxy-trans-but-3-enoate at 217° C to give cis-trans mixture in a 1:10 ratio.