Synthesis of some 6-methylidene-9-purine acyclic nucleosides with expected anti-HIV activity

Reaction of 6-chloro,9-(2-acetoxyethoxymethyl)purine 1 with ethyl cynoacetat, malononitrile and diethyl malonate in presence of NaH and DMF yielded the corresponding 6-methylidene derivatives 2a-c, which were deprotected by treatment with methanolic Ammonia to yield 3a-c. During the reaction of 1 with cyanoacetamide deacetylation took place spontaneously resulting in the deprotected acyclic nucleoside 4. Treatment of 2a with methyliodide in presence of NaH and DMF yielded the N-methyl derivative 5. NMR and mass spectra of the synthesized compounds are discussed.