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Noncovalent Catalysis for Enantioselective Direct Aldol Reaction of 3‐Acetylcoumarins to Pyrazole‐4,5‐diones

The first catalytic enantioselective direct aldol reaction of 3-acetylcoumarins to pyrazole-4,5-diones is reported and shown to proceed through noncovalent substrate activation by a quinine-derived bifunctional tertiary amino-amide as the catalyst. The densely functionalized products, consisting of an oxygen-containing quaternary stereocenter and bearing two biologically relevant heterocycles, are generally obtained in high yields with moderate to excellent enantioselectivities.