Unsaturated Analogues of Acyclic Nucleoside Phosphonates an Unusual Arbuzov Reaction with Unactivated Triple Bond

Phosphonates 6 and 8 were prepared by reaction of the corresponding chloroalkenes 5 and 7 with triethyl phosphte. Dealkylation of 6 and 8, combined with acid hydrolysis in case of 8, gave phosphonic acids 3a and 4b. By contrast, chloroalkyne 9 and triethyl phosphite afforded only 2-amino-6-chloro-N 9 -ethylpurine (10). The same reaction performed in the presence of tetrabutyl-ammonium iodide led to diphosphonate 11. Compound 4b inhibited the growth of murine leukemia L1210 in culture (IC50 10μM).