Regioselective Asymmetric Alkynylation of N–Alkyl Pyridiniums

Disclosed in this communication is a novel asymmetric addition of alkynyl nucleophiles to N-alkyl pyridinium electrophiles. The coupling is effected under mild and simple reaction conditions, affording dihydropyridine products with complete regiochemical and stereochemical control. In addition to several manipulations of the dihyropyridine products, the utility of this transformation is demonstrated through a concise, dearomative, and asymmetric synthesis of (+)-lupinine, a natural acetylcholine esterase inhibitor.