Alkylations of heterocyclic ambident anions. IV. Alkylation of 5-carbethoxy- and 5-nitro-2-pyridone salts

Alkylation of the 2-hydroxypyridine anion in ionic liquid media

“…The unexpected decreased influence of the substrate cation (M) on the distribution of N-vs O-alkylation products in comparison with the situation in molecular liquids (organic solvents) [27][28][29] could be explained by the ILs leveling effect. An exchange reaction might take place between the substrate cation (M) and the bulky hard cation of the IL.…”

“…2-Hydroxypyridine anion 2 forms two isomeric products in its reactions with electrophilic reagents -N-substituted (4) and O-substituted (5) derivatives [27][28][29][30]. Particularities of the chosen solvent, the impact of the cation connected with the substrate anion, and other factors influencing the transformation rates, as well as the regioselectivity of reactions in these alkylation reactions performed in non-conventional solvents, ILs, are discussed.…”

“…As a result, a loose ion pair is formed between the ambident 2-hydroxypyridine anion and the bulky IL cation, and any specific cation−anion interaction between the substrate ions is diminished or even fully abolished, which explains the IL leveling effect. The mentioned ion exchange causes a decrease in the specific interaction even of the silver cation with the 2-hydroxypyridine anion, wich makes the well-known effect of the silver ion very much less powerful in ILs in comparison with molecular liquids such as N,N-dimethylformamide [28,29]. Gas chromatographic (GC) analyses were carried out on a Hewlett Packard 5890 instrument using a flame ionization detector with a hydrogen flow rate of 30 ml/min, air flow rate of 300 ml/min, and helium flow rate of 25 ml/min.…”

The Liquid/Solid Alkylation of Alkali Metal Pyrazolates

“…The literature on the electrophilic reactions of organic ambident anions shows that in a variety of cases [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] heterogeneity in reaction conditions plays a role in determining the courses of the reactions. We decided to study the effect that heterogeneity has on the reactions of alkali metal salts of various pyrazolate anions with primary alkyl halides.…”

Arenesulfonylheterocycles (I): Synthesis and reactions of 2‐benzenesulfonyl‐4,5‐dichloropyridazin‐3‐ones with amines

“…Pyridazin-3-ones are also the ambident anions under basic conditions [3,4]. The regioselectivity of the N/Oalkylation for a nitrogen heterocyclic ambident anion such as 2-pyridone and 3-pyridazinone depends on the nature of the base, the structure of alkyl halide, substituents on the heterocycles, reaction temperature and the solvent [5,6]. Similarly, the direct sulfonylation of pyridazin-3-ones under basic condition should furnish N-and/or O-sulfonylated products.…”