Isolation, characterization and synthesis of novel impurity in antiviral drug: Valacyclovir hydrochloride

During the process development of valacyclovir hydrochloride (1), one novel impuritywas detected inHPLC analysis. This impuritywas isolated, synthesized and characterized as 2-[(2-amino-1,6-dihydro-6-oxo-9H-purin- 9-yl)methoxy]ethyl-N-(acetyl)-L-valinate (2), by 1H NMR, IR and mass spectral data.