Structural-based design and synthesis of novel 9-deazaguanine derivatives having a phosphate mimic as multi-substrate analogue inhibitors for mammalian PNPs.

9-(5',5'-Difluoro-5'-phosphonopentyl)-9-deazaguanine (DFPP-DG) was designed as a multi-substrate analogue inhibitor against purine nucleoside phosphorylase (PNP) on the basis of X-ray crystallographic data obtained for a binary complex of 9-(5',5'-difluoro-5'-phosphonopentyl)guanine (DFPP-G) with calf-spleen PNP. DFPP-DG and its analogous compounds were synthesized by the Sonogashira coupling reaction between a 9-deaza-9-iodoguanine derivative and omega-alkynyldifluoromethylene phosphonates as a key reaction. The experimental details focused on the synthetic chemistry along with some insights into the physical and biological properties of newly synthesized DFPP-DG derivatives are disclosed.