69856-71-9Relevant academic research and scientific papers
1-Acyl-4-alkylidene-1,4-dihydropyridines, 7. Activation with Boron Trifluoride: Intermolecular Acyl Group Transfer and Formation of 1-(4-Pyridyl)-2-alkanones
Anders, Ernst,Will, Wolfgang,Stankowiak, Achim
, p. 3192 - 3204 (2007/10/02)
1-Acyl-4-alkylidene-1,4-dihydropyridines 5, representatives of the thermally stable enamides, can be activated by means of boron trifluoride 6, so the ketones 7 result from attack of 6 on 5 (intermolecular acyl group transfer).The mechanism of this reaction, which has not previously been observed for enamides, is strongly suggested to be as follows: 5 and 6 form first the adduct 21, which attacks 5 with formation of 27.Special examples of 5 (11 and 12) are found to be reactive enough that the ketone 7h or the sulfone 15 can be obtained from their isolable precursors (14 and 13) without Lewis-acid activation. 13 is particularly noteworthy: being the precursor of the salt 16, which is generated in situ, it serves as an extremely effective tosylating agent.Even tertiary alcohols are attackted by 16.
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
Lee, Cheuk Man,Sammes, Michael P.,Katritzky, Alan R.
, p. 2458 - 2462 (2007/10/02)
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.
