Finally, to demonstrate the wider applicability of this enzymatic transglycosylation approach for the preparation of high value nucleoside building blocks, we sought to prepare the 15 Nlabelled nucleoside 58 starting from 51 (Figure ). N labelled nucleosides are used extensively in structural biology and as chemical probes to explore their enzymatic incorporation into DNA. The incorporation of N building blocks bearing nonnatural nucleobases typically involve the incorporation of the 15 N label, followed by a glycosylation step. Glycosylation is achieved enzymatically using a NP, or via a synthetic glycosylation step (e.g., Vorbrüggen) to prepare the final nucleoside. Accordingly, we prepared the novel N-labelled nucleoside 58 in two steps starting from 51. Acetyl protection of the hydroxyl groups afforded 57 in 90% yield, which was necessary to solubilise the nucleoside for the Pd-catalysed cross coupling with N-labelled benzoyl amide. The cross coupling and acetyl deprotection were performed in one-pot on a 0.3 mmol. scale, affording 58 in 45% yield (48 mg).