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Palladium-catalyzed allylation of 2- and 4-alkylpyridines via N-allyl alkylidene dihydropyridine intermediates
Journal article   Peer reviewed

Palladium-catalyzed allylation of 2- and 4-alkylpyridines via N-allyl alkylidene dihydropyridine intermediates

Grant N. Shivers and F. Christopher Pigge
Tetrahedron letters, Vol.128, 154701
09/2023
DOI: 10.1016/j.tetlet.2023.154701
PMCID: PMC10569290
PMID: 37841749
url
https://pmc.ncbi.nlm.nih.gov/articles/PMC10569290/pdf/nihms-1926973.pdfView
Open Access

Abstract

A method to introduce allyl or cinnamyl groups to the picolyl positions of 2- or 4-alkylpyridines is described. Substituted N-allyl pyridinium salts are first treated with base (KOtBu) followed by catalytic [(η3-allyl)PdCl]2 and PPh3 to result in formal Pd-catalyzed transfer of N-allyl groups to the pyridine periphery. The reaction is believed to proceed through initial formation of nucleophilic alkylidene dihydropyridine intermediates that react with (π-allyl)Pd(II) electrophiles, thereby regenerating N-allyl pyridinium cations. Catalytic turnover and liberation of pyridine products is then achieved by oxidative addition of Pd(0) to these activated allyl groups.

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