Enantioselective Dearomatization of Pyridinium Salts by Copper‐Catalyzed C4‐Selective Addition of Silicon Nucleophiles
Yao Xiao, Zhiyuan Zhao, Sebastian Kemper, Elisabeth Irran, Martin Oestreich
Abstract
Abstract A copper‐catalyzed C4‐selective addition of silicon nucleophiles released from an Si−B reagent to prochiral pyridinium triflates is reported. The dearomatization proceeds with excellent enantioselectivity using Cu(CH 3 CN) 4 PF 6 as the precatalyst and ( R , R )‐Ph‐BPE (1,2‐bis[(2 R ,5 R )‐2,5‐diphenylphospholan‐1‐yl]ethane) as the chiral ligand. A carbonyl group at C3 is required for this, likely acting a weak donor group to preorganize and direct the nucleophilic attack towards C4. The resulting 4‐silylated 1,4‐dihydropyridines can be further converted into functionalized piperidine derivatives.
Topics & Concepts
PyridiniumNucleophileChemistryEnantioselective synthesisPiperidineReagentCatalysisCopperOrganic chemistryLigand (biochemistry)Combinatorial chemistrySiliconChiral ligandMedicinal chemistryReceptorBiochemistryCatalytic C–H Functionalization MethodsCyclopropane Reaction MechanismsAsymmetric Synthesis and Catalysis