Efficient Method for Selective Introduction of Substituents as C(5) of Isoleucine and Other α-Amino Acids

[reaction: see text] A useful process for the position-selective remote bromination of N-trifluoroacetyl-alpha-amino esters is illustrated for the isoleucine case. The 5-bromoisoleucine derivative shown above can be used for the synthesis of many modified amino acids, as described herein.