Divergent Access to Chiral C2- and C3-Alkylated Pyrrolidines by Catalyst-Tuned Regio- and Enantioselective C(sp3)-C(sp3) Coupling

Novel-substituted pyrrolidine derivatives are widely used in drugs and bioactive molecules. The efficient synthesis of these valuable skeletons, especially enantiopure derivatives, is still recognized as a key bottleneck to overcome in chemical synthesis. Herein, we report a highly efficient catalyst-tuned regio- and enantioselective hydroalkylation reaction for the divergent synthesis of chiral C2- and C3-alkylated pyrrolidines through desymmetrization of the readily available 3-pyrrolines. The catalytic system consists of CoBr₂ with a modified bisoxazoline (BOX) ligand, which can achieve the asymmetric C(sp³)-C(sp³) coupling via the distal stereocontrol, providing a series of C3-alkylated pyrrolidines in high efficiency. Moreover, the nickel catalytic system allows the enantioselective hydroalkylation to synthesize the C2-alkylated pyrrolidines through the tandem alkene isomerization/hydroalkylation reaction. This divergent method uses readily available catalysts, chiral BOX ligands, and reagents, delivering enantioenriched 2-/3-alkyl substituted pyrrolidines with excellent regio- and enantioselectivity (up to 97% ee). We also demonstrate the compatibility of this transformation with complex substrates derived from a series of drugs and bioactive molecules in good efficiency, which offers a distinct entry to more functionalized chiral N-heterocycles.

Regio- and Stereoselective Alkylboration of Endocyclic Olefins Enabled by Nickel Catalysis

Whereas there is a significant interest in the rapid construction of diversely substituted saturated heterocycles, direct and modular access is currently limited to the mono-, 2,3-, or 3,4-substitution pattern. This Communication describes the straightforward and modular construction of 2,4-substituted saturated heterocycles from readily available materials in a highly stereo- and regioselective manner, which sets the stage for numerous readily accessible drug motifs. The strategy relies on chain walking catalysis.