Asymmetric Conjugate Addition of Vinyl Arene-Derived Chiral Benzylcopper Nucleophiles.

We report the copper-catalyzed asymmetric conjugate addition of vinyl arene-derived nucleophiles to α,β-unsaturated diesters. Due to the high electrophilicity of α,β-unsaturated diesters toward nucleophilic copper catalysts, inclusion of vinyl arenes as pronucleophiles is challenging due to chemoselectivity issues in a multicomponent reaction compared with those of other successful examples of dienes, allenes, and enynes. In this method, chemoselective generation of a chiral benzylic copper intermediate and its stereoselective addition to α,β-unsaturated diesters provided organoboron adducts with contiguous stereogenic centers with good levels of diastereoselectivity and enantioselectivity (≤85:15 diastereomeric ratio and 99% enantiomeric excess, respectively).

Asymmetric Synthesis of β-Aminoboronates via Copper-Catalyzed Reductive Coupling of Vinyl Boronates with Imines.

We report a copper-catalyzed asymmetric reductive coupling of vinyl boronates with imines, which directly access enantiomerically enriched β-aminoalkylboronates. Stereoselective addition of the in situ generated chiral α-borylalkyl copper to -phosphinoyl imines provided target products in good yields with high diastereo- and enantioselectivity. Vinyl boronate with methylated acenaphthoquinone as a boron ligand was essential to efficiently spawn asymmetric products, and organic transformations of the boron moiety, along with the easily removable -protecting group, proved their synthetic utility.

Copper-catalysed asymmetric reductive cross-coupling of prochiral alkenes.

Asymmetric construction of C(sp)-C(sp) bond with good stereocontrol of the two connecting carbon centres retaining all carbon or hydrogen substituents is a challenging target in transition metal catalysis. Transition metal-catalysed reductive coupling of unsaturated π-substrates is considered as a potent tool to expediently develop the molecular complexity with high atom efficiency. However, such an asymmetric and intermolecular process has yet to be developed fully.