Efficient synthesis of protected 3′-deoxyadenosine and 3′-deoxyguanosine from adenosine and guanosine

Highly efficient synthesis of protected 3′-deoxyadenosine and 3′-deoxyguanosine from adenosine and guanosine were described. The 2′,3′-diol of protected adenosine and guanosine were reacted with α-acetoxyisobutyryl bromide to yield 9-(2′-O-acetyl-3′-bromo-5′-O-tert-butyldiphenylsilyl-3′-deoxy-β-d-xylofuranosyl)-6-N-benzoyl adenine and 9-(2′-O-acetyl-3′-bromo-5′-O-tert-butyldiphenylsilyl-3′-deoxy-β-d-xylofuranosyl)-2-N-(N′,N′-dimethylaminomethylene) guanine and subsequently heated with tri-n-butyltin hydride in the presence of 2,2′-azobisisobutyronitrile to afford the protected 3′-deoxyadenosine and 3′-deoxyguanosine in 66–73% over all yield.