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C6-azolyl purine nucleoside products are prepared in high yields under solvent-and catalyst-free conditions via C-N coupling reaction of unprotected 6-chloropurine nucleosides and N-heterocycles, providing a unifying, simple and environmentally friendly complement to the available methods. † Electronic supplementary information (ESI) available: General information, experimental procedures, and characterization data for the products including spectroscopic information. See

We report, herein, aminocatalytic coupling of α-substituted acrylaldehydes with α-diazoesters, leading to chemoselective C–H insertion or cyclopropanation depending on α-substituents of diazoesters. A chiral primary–secondary diamine catalyst derived from l-tert-leucine enabled the efficient promotion of both C–H insertion and cyclopropanation pathways in good yields and high enantioselectivities at room temperature without any metal or a Lewis acid cocatalyst. Mechanistic studies uncovered an iminium ion-mediated 1,3-dipolar cycloaddition pathway, wherein the electronic nature of diazocarbons dictates the chemoselectivity in this aminocatalytic cycle.