Synthesis and Biological Evaluation of 6-(Alkyn-1-yl)furo[2,3<i>-d</i>]pyrimidin-2(3<i>H</i>)-one Base and Nucleoside Derivatives

Derivatives of the 2'-deoxynucleoside of furo[2,3-d]pyrimidin-2(3H)-one with long-chain alkyl (or 4-alkylphenyl) substituents at C6 exhibit remarkable anti-VZV (varicella-zoster virus) potency and selectivity, and analogous 2',3'-dideoxynucleoside derivatives show anti-HCMV (human cytomegalovirus) activity. We now report a synthetic approach that enables the preparation of long-chain 6-(alkyn-1-yl)furo[2,3-d]pyrimidin-2(3H)-ones in which the rodlike acetylene spacer replaces the 4-substituted-phenyl ring at C6. Analogues with methyl, beta-d-ribofuranosyl, beta-d-arabinofuranosyl, and 2-deoxy-beta-d-erythro-pentofuranosyl substituents at N3 have been prepared. Long-chain derivatives at C6 in the 2'-deoxynucleoside series showed virus-encoded nucleoside kinase-sensitive anti-VZV activity. Surprisingly, 3-methyl-6-(octyn-1-yl)furo[2,3-d]pyrimidin-2(3H)-one (prepared as a negative anti-VZV test control) exhibited anti-HCMV activity, which supports the possibility of development of non-nucleoside anti-HCMV agents originating from uncomplicated derivatives of such bicyclic ring systems.