Scheme 1. Synthesis of N-linked Glycopeptide Fragment 1: β-hLH(chitobiose)[S1−Y37] (A) and Peptide Fragment 2: β-hLH[Z38−G71] (B).

Amino acid residues bearing acid-labile protecting groups shown in deep red, pseudoproline dipeptides shown in orange (underlined), and Acm-protected Cys residues shown in purple. Chitobiose glycan shown in blue, and thioester functionalities shown in green. Cocktail B: 88% TFA, 5% H₂O, 5% phenol (PhOH), 2% triisopropylsilane (TIPSH).