A short and efficient synthesis of the tRNA nucleosides PreQ0 and archaeosine.

Modified nucleosides in tRNAs play an important role in the translational process. They fine tune the codon-anticodon interactions and they influence the folding and stabilisation of the tRNA structure. Herein, we present a novel synthetic route to the highly modified nucleosides PreQ(0) and archaeosine. The synthesis involves coupling of a protected 7-cyano-7-deazaguanosine nucleobase with a TBDMS and isopropylidene protected chloro-ribose unit yielding the PreQ(0) nucleoside after deprotection. This PreQ(0) nucleoside is then used as the starting material for the synthesis of archaeosine providing the first total synthetic access to this hypermodified RNA nucleoside.