Organocatalytic Enantioselective Aza‐Michael Addition of Purine Bases to α,β‐Unsaturated Ketones

Abstract

Abstract The first organocatalytic enantioselective aza‐Michael addition of purine bases to α,β‐unsaturated ketones has been developed, affording Michael adducts in moderate to high yields (up to 96% yield) and high to excellent enantioselectivities (up to >99% ee ). A wide range of α,β‐unsaturated ketones including aliphatic and aromatic enones are tolerated in this process, generally demonstrating good reactivity, regioselectivity and enantioselectivity. The aromatic α,β‐unsaturated ketones showing quite low reactivity in the reported catalytic systems, were first successfully employed as Michael acceptors in this transformation, yielding high enantioselectivities (up to 94% ee ). The utility of this method was also applied for the synthesis of enantioenriched non‐natural nucleoside analogues with potential biological activities.