Scheme 4. Synthesis of PNA-linked ponatinib fragments. (A) Acceptor conjugate. (B) Donor conjugates. Reagents and conditions: (a) HATU, NMM, DMF, rt, 30 min; (b) TFMSA, TFA, TIS, rt, 3 h; (c) HATU, NMM, NMP, rt, 30 min; (d) TFA, TIS, EDT, H₂O, rt, 3 h. Apostrophe = Bhoc protecting group.