Synthetic Applications of N-N Linked Heterocycles. Part 8. Regiospecific Synthesis of 4-(α-Acylalkyl)pyridines by Attack of Lithium Enolates of Ketones γ to N-(2,6-Dimethyl-4-oxopyridin-1-yl)pyridinium Salts

Article abstract of DOI:10.1039/P19800002458

The addition of N-(2,6-dimethyl-4-oxopyridin-1-yl)pyridinium salts (2) - (4) to lithium enolates (1) of ketones in tetrahydrofuran at low temperatures gives regiospecifically high yields of 1,4-dihydro-adducts (5) - (7).These are readily isolated and can be decomposed under free-radical conditions, also in high yield, to 4-(α-acylalkyl)pyridines (8) - (10).Unsymmetrical dialkyl ketones give a mixture of two isomeric products, the ratio depending upon reaction conditions and steric factors. αβ-Unsaturated ketones, however, give products resulting from reaction exclusively at the position α' to the carbonyl group.