Scheme 2.

Synthesis of ProTide-Based 2-PMPA prodrug 16.a
aReagents and conditions: (a) H2, Pd/C, EtOAc; (b) POC-Cl, Et3N, DMF, 60 °C; (c) TMSBr, CHCl3, rt; (d) P(OPh)3, pyridine, 115 °C; (e) SOCl2, ACN, 70 °C; (f) L-alanine isopropyl ester, DIEA, DCM, between −30 °C and −10 °C.