Used primarily as an intermediate in the synthesis of antiviral medications, particularly in the production of penciclovir and its prodrugs like famciclovir. It plays a key role in the development of drugs targeting herpesvirus infections, including herpes simplex virus (HSV) and varicella-zoster virus (VZV). Due to its structural similarity to guanosine, it interferes with viral DNA replication when phosphorylated in infected cells, making it valuable in antiviral research and pharmaceutical development.