Highly Enantioselective Reactions of Cyclohexanone andβ,γ-Unsaturatedα-Keto Ester: The Tuning of Chemo-selectivities by Secondary and Primary Amine Catalysts

Switchable Chemoselectivity in [3 + 3] Annulation of β,γ-Unsaturated α-Ketoesters and 1H-Pyrazol-5-amines by Cooperative Acid Catalysis with NiII and InI

The exchange of the metal ion from Ni(II) to In(I) leads to a switch in the chemoselectivity of the [3 + 3] annulation of β,γ-unsaturated α-ketoesters and 1H-pyrazol-5-amines in the presence of phosphoric acid 1, affording functionalized 1H-pyrazolo[3,4-b]pyridines 4 in up to 97% yields and highly enantioselective 4,5-dihydro-1H-pyrazolo[3,4-b]pyridines 5 in up to 92% yield and 99% ee.

Formal asymmetric catalytic thiolation with a bifunctional catalyst at a water-oil interface: synthesis of benzyl thiols

The enantioselective conjugated addition of tritylthiol to in situ generated ortho-quinone methides (o-QMs) is catalyzed by an acid-base bifunctional squaramide organocatalyst. The transformation proceeds with high yield (up to 99 %) and stereoselectivity (up to 97:3 e.r.) using water as solvent under mild conditions. The catalyst system provides a new strategy for the synthesis of optically active benzyl mercaptans. Control experiments suggested that o-QMs are generated by the tertiary amine moiety of the squaramide organocatalyst and that the water-oil biphase is crucial for achieving high reactivity and stereoselectivity.