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. Author manuscript; available in PMC: 2011 May 9.
Published in final edited form as: Bioorg Med Chem Lett. 2009 Nov 13;20(1):60–64. doi: 10.1016/j.bmcl.2009.11.031

Scheme 4.

Scheme 4

Reagents and condition: (a) (i) TBSCl, imidazole, DMF, rt, overnight, 80%, (ii) DIAD, TPP, 80 °C, 30 min, 75%, (iii) LiN3, DMF, 100 °C, 24 h, 70%; (b) purine base, BSA, TMSOTf, CH3CN, 70 °C, 18 h, 34–61%; (c) (i) TBAF/acetic acid (v/v: 1:0.2), THF, rt, 4–6 h, (ii) anomer separation on silica gel, (iii) nucleophilic reagents in the case of 2- and/or 6-chloro purines in one to three steps in 20–95% yield.