Enantioselective and Regiodivergent Addition of Purines to Terminal Allenes: Synthesis of Abacavir
An atom-economic and regiodivergent Rh- and Pd-catalyzed coupling of purine derivatives and terminal allenes has been developed. High regioselectivity and excellent enantiomeric excess and yields were achieved with various functionalized substrates. Additionally, the developed methodology was applied to a straightforward synthesis of carbocyclic nucleoside 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.
N. Thieme, B. Breit, Angew. Chem. 2017, 129, 1542-1546; () Angew. Chem. Int. Ed. 2017, 56, 1520-1524. ( .