Unusual deoxygenation and reactivity studies related to O6-(benzotriazol-1-yl)inosine derivatives

New and unusual developments related to the chemistry of O-6-(benzotriazol-1-yl)inosine derivatives are reported. First, a simple, scalable method for their syntheses via the use of PPh3/I-2/HOBt has been developed and has been mechanistically investigated by P-31{H-1} NMR. Studies were then conducted into a unique oxygen transfer reaction between O-6-(benzotriazol-1-yl)inosine nucleosides and bis(pinacolato)diboron (pinB-Bpin) leading to the formation of C-6 (benzotriazol-1-yl)purine nucleoside derivatives and pinB-O-Bpin. This reaction has been investigated by B-11{1H} NMR and compared to pinB-O-Bpin obtained by oxidation of pinB-Bpin. The structures of the C-6 (benzotriazol-1-yl)purine nucleosides have been unequivocally established via Pd-mediated C-N bond formation between bromo purine nucleosides and IH-benzotriazole. Finally, short and extremely simple synthesis of 1,N-6-ethano-and 1,N-6-propano-2'-deoxyadenosine are reported in order to demonstrate the synthetic versatility of the O-6-(benzotriazol-1-yl)inosine nucleoside derivatives for the assembly of relatively complex compounds.