Scheme 1. Synthesis of GalNAc derivatives with Alk-NCS, Aryl-NCS coupling functionality and without the coupling functionality. (A) (i) MeOH, APTS, H2, Pd–C (100%), (ii) MeOH/H2O, IRN78 (77%), (iii) DMF, 1,1′-thiocarbonyldi-2(1H)-pyridone (88%), (iv) DMF, p-phenylene diisothiocyanate (85%). (B) (i) DCM, 2-(2-ethoxyethoxy)ethanol, molecular sieves (73%), (ii) MeOH/H2O, IRN78 (77%).
