Enantioselective and Regiodivergent Addition of Purines to Terminal Allenes: Synthesis of Abacavir

The rhodium‐catalyzed atom‐economic asymmetric N‐selective intermolecular addition of purine derivatives to terminal allenes is reported. Branched allylic purines were obtained in high yields, regioselectivity and outstanding enantioselectivity utilizing a Rh/Josiphos catalyst. Conversely, linear selective allylation of purines could be realized in good to excellent regio‐ and E/Z‐selectivity with a Pd/dppf catalyst system. Furthermore, the new methodology was applied to a straightforward asymmetric synthesis of carbocyclic nucleoside abacavir.