Synthesis of 3-alkyl-2-pyrazinyl methyl ketones and related compounds

Pyrazines in foods

“…Synthesis of acetylpyrazines by a two-step procedure has been reported by Mookherjee and Klaiber (1972). The process essentially involves the oxidation of a monohaloalkylpyrazine to its corresponding ketone through the use of either sodium-2-propanenitronate or pyridine 1-oxide.…”

A Green and Scalable Cobalt(II)-Catalyzed Oxidation of 2-Ethyl-3-methylpyrazine

“…The TEMPO adduct (8) was detected by the LC-MS, and m/z value of 278 was observed, which was formed by the interaction between EMP and TEMPO. The structure of 8 was further confirmed by 1 H NMR spectroscopy after the isolation. All the results suggest the involvement of a radical mechanism.…”

“…The resulting crude residue was purified via column chromatographyon silica gel (petroleum ether/EtOAc, V∶V＝ 4∶1) to afford the intermediate with TEMPO (8). The desired AMP product was not observed and the intermediate with TEMPO (8) could be detected by 1 The deuteration of EMP was performed in a schlenk tube (50 mL) equipped with a magnetic stirrer. The EMP material (1 mmol), p-toluenesulfonic acid (0.4 mmol) and D 2 O (1 mL) were added into the tube, and the mixture was stirred under 120 ℃ for 24 h. The deuterated product was purified by vacuum distillation.…”

“…So far, there are two methods reported about the production of AMP by 2-ethyl-3-methylpyrazine (EMP). Mookherjee and Klaiber [1] reported a method for producing acetyl substituted pyrazine by oxidation of the corresponding α-bromide in 1972. In this method, α-bromide was obtained by the reaction of hydrocarbyl-substituted pyrazine with N-bromosuccinimide (NBS), and alkali metal and 2-propanenitronate were used to obtain a high yield of AMP (about 66%) in short reaction time (Scheme 1a).…”

Chromate oxidation of alkylpyrazines

“…Using 2,6-dichlorophenylethylene (1) to avoid side products resulting from sulfonation into the phenyl ring, it is possible to isolate a pure carbyl sulfate. Dropwise addition of olefin 1 into liquid sulfur dioxide in 1,2-dichloroethane gave the carbyl sulfate 2 in 96% yield.…”