Construction of spirocyclic oxindole derivatives by copper-catalyzed enantioselective Michael/hemiketalization in aqueous media

Synthesis of enantioenriched spirocyclic oxindoles catalyzed by bifunctional thiourea

The spirocyclic oxindole scaffold, prevalent in natural products and bioactive compounds, holds paramount significance in organic chemistry. We report an efficient strategy for the construction of enantioenriched spirocyclic oxindoles bearing four consecutive stereogenic centers via a Michael-Mannich cascade reaction catalyzed by a bifunctional thiourea. The desired products were obtained in excellent yields (up to 99%) with high stereoselectivities (up to >20 : 1 d.r., >99% ee). A scaled-up reaction variant proceeded smoothly, highlighting the potential applicability of this method in the synthesis of bioactive compound libraries.

A copper-catalyzed asymmetric Friedel-Crafts hydroxyalkylation of pyrazole-4,5-diones with 5-aminoisoxazoles

An asymmetric Friedel-Crafts hydroxyalkylation reaction of 5-aminoisoxazoles with pyrazole-4,5-diones was developed under the catalysis of 5% chiral copper complexes. This reaction exhibits functional group tolerance and excellent enantioselectivity. Moreover, the reaction can be scaled up and its mechanism was studied.

Enantioselective Michael addition of malonates to β,γ-unsaturated α-ketoesters catalysed by Cu(II) complexes bearing binaphthyl-proline hybrid ligands

High yields (up to 96%) and high ee (up to 92%) were achieved for chiral copper(II) complex-catalysed enantioselective Michael addition of malonates to β,γ-unsaturated-α-ketoesters. The chiral ligands took advantage of both the binaphthyl and the proline moieties, and substituents with different electronic and steric features could be tolerated. The reactions could be carried out under mild conditions, and a gram scale reaction could be realised without the loss of yield and enantioselectivity.