Access to 3-Deazaguanosine Building Blocks for RNA Solid-Phase Synthesis Involving Hartwig-Buchwald C-N Cross-Coupling

3-Deazaguanosine (c(3)G) and phosphoramidite derivatives thereof that allow incorporation of this modification into RNA are needed for atomic mutagenesis experiments to explore mechanistic aspects of ribozyme catalysis. Here, we report a practical synthesis for c(3)G phosphoramidites from inexpensive starting materials. The key reaction sequence is a silyl-Hilbert-Johnson nucleosidation followed by Hartwig-Buchwald cross-coupling to achieve the N-2-phenoxyacetyl protected c(3)G nucleoside.