title: β-Selective Reductive Coupling of Alkenylpyridines with Aldehydes and Imines via Synergistic Lewis Acid/Photoredox Catalysis.
abstract: Umpolung (polarity reversal) strategies of aldehydes and imines have dramatically expanded the scope of carbonyl and iminyl chemistry by facilitating reactions with non-nucleophilic reagents. Herein, we report the first visible light photoredox-catalyzed β-selective reductive coupling of alkenylpyridines with carbonyl or iminyl derivatives with the aid of a Lewis acid co-catalyst. Our process tolerates complex molecular scaffolds (e.g., sugar, natural product, and peptide derivatives) and is applicable to the preparation of compounds containing a broad range of heterocyclic moieties. Mechanistic investigations indicate that the key step involves single-electron-transfer reduction of aldehydes or imines followed by the addition of resulting ketyl or α-aminoalkyl radicals to Lewis acid-activated alkenylpyridines.
authors.affiliation: Department of Chemistry and Institute of Chemical Biology and Drug Discovery, Stony Brook University , Stony Brook, New York 11794-3400, United States.
authors.forename: Katarzyna N
authors.identifier: http://orcid.org/0000-0003-4849-3927
authors.initials: KN
authors.lastname: Lee
authors.affiliation: Department of Chemistry and Institute of Chemical Biology and Drug Discovery, Stony Brook University , Stony Brook, New York 11794-3400, United States.
authors.forename: Zhen
authors.identifier: http://orcid.org/0000-0002-6608-7933
authors.initials: Z
authors.lastname: Lei
authors.affiliation: Department of Chemistry and Institute of Chemical Biology and Drug Discovery, Stony Brook University , Stony Brook, New York 11794-3400, United States.
authors.forename: Ming-Yu
authors.identifier: http://orcid.org/0000-0002-3055-6662
authors.initials: MY
authors.lastname: Ngai