Wengang Guo

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.

Asymmetric Catalytic 1,2-Hydroperoxidation of Isatin-Derived Ketimine with Hydrogen Peroxide in the Crowding Environment of PEGs

The first enantioselective catalytic 1,2-hydroperoxidation has been achieved in the presence of PEG-600 using an acid-base bifunctional chiral squaramide as the organocatalyst, affording a range of enantioenriched α-N-substituted hydroperoxides bearing an oxindole moiety with excellent stereoselectivities (up to 99% ee).

An amphiphilic organic catalyst for the direct asymmetric Michael addition of cycloketone to nitroolefins in water

Abstract A series of amphiphilic proline-derived mercapto imidazole organic catalysts were synthesized and shown to be very effective with an acid cocatalyst for the asymmetric Michael addition reaction of ketones to nitroolefins with high diastereoselectivity (up to 99:1) and execellent enantioselectivity (up to 96%) using water as solvent.