Enantioselective Synthesis of Dihydropyrazolo[3,4‐<i>b</i>]pyridin‐6‐ones via N‐Heterocyclic Carbene Catalyzed [3+3] Cycloaddition of <i>α</i>‐Bromoenals with 5‐Aminopyrazoles

Abstract

Abstract An N‐heterocyclic carbene (NHC) catalyzed asymmetric [3+3] annulation of α ‐bromoenals with 5‐aminopyrazoles is described. Using the established methodology, a structurally diverse set of high value dihydropyrazolo[3,4‐ b ]pyridine‐6‐ones were efficiently constructed in high yields (up to 99%) with excellent enantioselectivities (up to &gt;99%). The easily available starting materials, broad substrate scope, mild reaction conditions, excellent yield and enantioselectivity make this strategy attractive for the asymmetric construction of pyrazolo‐fused pyridone derivatives. magnified image

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