Synthesis and biological evaluation of some alpha-[6-(1'-carbamoylalkylthio)-1 H-pyrazolo[3,4-D]pyrimidin-4-yl]thioalkylcarboxamide acyclonucleosides

The reaction of 1H-pyrazolo3,4-d]pyrimidin-4,6-dithione 11 with compounds 12a-c produces ethyl alpha-6-(1'-carboethoxyalkylthio)-1 H-pyrazolo3,4-d]pyrimidin-4-yl]thioalkylates 13a-c, respectively. These heterocycles were alkylated, separately, with alkylating agents 14, 15, and 16 to afford, predominately, the N(1)-acyclic nucleosides (17-19)a-c, which were deprotected to give the desired products (20-22)a-c. All synthetic compounds were characterized on the basis of their physical and spectroscopic properties. The acyclic nucleosides (20-22)a-c were evaluated for their inhibitory effects against the replication of varicella-zoster virus, human cytomegalovirus and M. tuberculosis. No marked biological activity was found.