Tricyclic etheno analogs of PMEG and PMEDAP: synthesis and biological activity

A series of novel 9-substituted (2-(3H-imidazo1,2-a]purin-3-yl)ethoxy)methylphosphonic and 4-substituted (2-(1H-imidazo2,1-b]purin-1-yl)ethoxy)methylphosphonic acids as tricyclic etheno analogs of potent antivirals and cytostatics PMEG and PMEDAP was synthesized and evaluated for their biological activity. Most of the compounds showed modest activity against varicella-zoster virus (VZV) and human cytomegalovirus (HCMV) except for (2-(9-oxo-5,9-dihydro-3H-imidazo1,2-a]purin-3-yl)ethoxy)methylphosphonic acid 8 which proved markedly active against VZV and HCMV. None of the compounds tested exhibited any significant cytostatic effect.