A process is provided for preparing a conjugate of Formula (I-A) or (I) comprising a polypeptide containing n number of tyrosine units, where n is an integer greater than or equal to 1, dispersed within the amino acid chain
having and amino terminus end (A
1
) and an acid terminus end (A
2
) of the protein or polypeptide and having a weight average molecular weight equal to or greater than 10,000 Daltons (10 kDa), wherein the conjugate comprises a number m of tyrosine conjugates (modified tyrosine residues) as depicted in Formula (I-A) or (I), where m is at least one and is less than or equal to n:
where X, Lg, L and R are as defined herein.