As the stereochemistry of the 2′-position is set by the aldolase used, changing to a different aldolase allows for alteration of this stereochemistry. Thus replacement of DERA by EcFSAWT 33 resulted in the synthesis of the nucleoside analogue vidarabine (2′-ara-OH adenosine, 29) (Table 1). Vidarabine was generated in a diastereomeric ratio of 90:10, vidarabine:adenosine. Finally, to characterize the 2′-OH, 2′-araOH, 2′-Me and 2′-F adenosine analogues by 1 H NMR 5 ml scale reactions were carried out and the products were purified by semipreparative HPLC. For adenosine the 1 H NMR spectra obtained was identical to the commercial standard. For the 2′-OH and 2′-Me analogues, the 1H NMR spectra confirmed the presence of a single diastereomer at the 2' postion. For vidarabine, the 1H NMR spectrum was identical to the commercial standard. For 2′-F adenosine 28, despite the aldolase step generating an epimeric mixture of 2′-F diastereomers, the 2′-F adenosine product was synthesized in a diasteromeric ratio of 98:2 favouring the desired "down" stereochemistry of the fluorine. These isomers were unable to be separated by semi-prep HPLC and were isolated together. This observation suggests that while the aldolase exhibits poor stereochemical control, one or both of the final two enzymes in the cascade are stereoselective for the desired fluorine diastereomer. Alongside the desired 2′-F adenosine we were also able to isolate the 2′-F inosine side product (supplementary 14.5), thereby demonstrating the potential to generate 2′ -functionalized inosine anlogues by addition of a deaminase enzyme to the cascade.