Preparation of 3-bromo-L-tyrosine and 3,5-dibromo-L-tyrosine.

L-Tyrosine is converted to 3-bromo-L-tyrosine in good yield by reaction with 1.2 equiv. of DMSO in HBr/AcOH, while reaction with 2.2 equiv. of DMSO under comparable conditions results in formation of 3,5-dibromo-L-tyrosine in good yield. This is the simplest, safest and most efficient method for the preparation of gram quantities of either 3-bromo-L-tyrosine or 3,5-dibromo-L-tyrosine.