Synthesis of a novel N-1 carbocyclic, N-9 butyl analogue of cyclic ADP ribose (cADPR)

A new analogue of cADPR was prepared through a synthetic pathway starting from 6-chloropurine which underwent two sequential alkylations at N-9 and N-1, with formation of the intermediate . The successive bis-phosphorylation of hydroxyalkyl functions, followed by deprotection and reprotection steps, afforded the derivative , the substrate for the cyclization reaction. This was carried out according to the Matsuda procedure and led to the intramolecular pyrophosphate bond formation, thus affording . The final deprotection of , in alkaline conditions, gave the target compound in good yield.