(N-Ethyl N-theophyllinyl-7' ethylamino)-2 oxo-2 dioxaphosphorinnane-1,3,2 [French] 70299-72-8 Phosphoramidic acid, N-ethyl-N-(2-(1,2,3,6-tetrahydro-1,3-dimethyl-2,6-dioxopurin-7-yl)ethyl)-, cyclic trimethylene ester