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Divergent Access to Chiral C2- and C3-Alkylated Pyrrolidines by Catalyst-Tuned Regio- and Enantioselective C(sp 3 )-C(sp 3 ) Coupling.

Xuchao WangJing XueZi-Qiang Rong
Published in: Journal of the American Chemical Society (2023)
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 CoBr 2 with a modified bisoxazoline (BOX) ligand, which can achieve the asymmetric C(sp 3 )-C(sp 3 ) 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.
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