Enantioselective Catalytic Dearomative Addition of Grignard Reagents to 4-Methoxypyridinium Ions

We describe a general catalytic methodology for the enantioselective dearomative alkylation of pyridine derivatives with Grignard reagents, allowing direct access to nearly enantiopure chiral dihydro-4-pyridones yields up 98%. The involves dearomatization in situ-formed N-acylpyridinium salts, employing alkyl organomagnesium reagents as nucleophiles and copper (I) complex catalyst. Computational mechanistic studies provide insights into origin reactivity enantioselectivity process.