Synthesis of 9-(2-phosphonylmethoxyethyl)adenine and related compounds

Abstract

Diethyl 2-hydroxyethoxymethanephosphonate (VIII) was converted into diethyl 2-halogenoethoxymethanephosphonates IXa and IXb by reaction with triphenylphosphine and tetrachloromethane or tetrabromomethane; analogous reaction of VIII with p-toluenesulfonyl chloride afforded diethyl 2-(p-toluenesulfonyloxy)ethoxymethanephosphonate (IXc). Reaction of sodium salt of adenine with compounds IX led to 9-(2-diethoxyphosphonylmethoxyethyl)adenine (X). Compound X was converted into 9-(2-phosphonylmethoxyethyl)adenine (II) by treatment with bromotrimethylsilane whereas alkaline hydrolysis of X gave ethyl ester Vb. Reaction of 9-(2-hydroxyethyl)adenine (IIIa) or its N6-benzoyl derivative IIIb with dimethyl p-toluenesulfonyloxymethanephosphonate (IV) in the presence of sodium hydride, followed by alkaline hydrolysis yielded methyl ester Va. Morpholide XI reacted with an inorganic phosphate and diphosphate to give 9-(2-phosphorylphosphonylmethoxyethyl)adenine (XII) and 2-(diphosphorylphosphonylmethoxyethyl)adenine (XIII), respectively.