Enantioselective Dearomatization of Pyridinium Salts by Copper‐Catalyzed C4‐Selective Addition of Silicon Nucleophiles

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(CH3CN)4PF6 as the precatalyst and (R,R)‐Ph‐BPE as the chiral ligand. A carbonyl group at C3 is required, likely acting a weak group to preorganize and direct the nucleophilc attack towards C4. The resulting 4‐silylated 1,4‐dihydropyridines can be further converted into functionalized piperidine derivatives.