Six symmetrical P-1,P-2-dinucleoside-5'-diphosphates (Np(2)Ns) have been synthesized from nucleoside-5'-H-phosphonate monoesters via a one-pot reaction in high yields. The key sequential hydrolysis protocol was developed based on the observation of reactive P-1,P-2,P-3-trinucleoside-5'-triphosphate intermediate on P-31 NMR. (C) 2013 Elsevier Ltd. All rights reserved.