“…Thus far, diverse deazanucleosides have been utilized for RNA atomic mutagenesis experiments; these are 3-deazacytidine (c 3 C), ,, 7-deazaadenosine (c 7 A), ,− ,, 3-deazaadenosine (c 3 A), , 1-deazaadenosine (c 1 A), ,,, and 7-deazaguanosine (c 7 G). , Furthermore, an efficient synthesis of 3-deazaguanosine (c 3 G) and the corresponding phosphoramidite has been reported recently and adds to the deazanucleoside tool box. , The missing piece, however, is 1-deazaguanosine (c 1 G), which is urgently needed for RNA atomic mutagenesis studies to probe the role of active site guanosines in catalysis of diverse ribozymes and for ligand recognition in the binding pockets of many riboswitches. In this work, we present a novel synthetic route toward c 1 G, the corresponding phosphoramidite and its incorporation into oligoribonucleotides by RNA solid-phase synthesis.…”