2-Methyl-5- pyrazine acetylation

Pyrazine, 3-methyl-2-acetyl Sd Pyrazine, 5-6-dimethyl-2-(2 -furyl) Sd... 

Pyrazine, 6-methyl-2-acetyl Sd Pyrazine, diethyl-dimethyl Sd Pyrazine, methyl Sd (roasted) ... 

In addition, compounds such as methyl pyrazine, furan methanol, acetyl furan, and several unidentified compounds with a buttery, caramel character were present only in the conventionally baked cake. 

Likewise, furfural (peak 16, 8.1 minutes) was observed in both microwave and conventionally baked cake, but at a significantly higher level in the latter. Methyl pyrazine (peak 15, 7.8 minutes), furan methanol (peak 17, 9.0 minutes), and acetyl furan (peak 22, 10.9 minutes), were present in the conventional cake samples as were two unidentified compounds (peaks 3 and 9, 3.3 and 5.0 minutes) observed to have buttery, caramel-like aromas. Several other minor peaks were also observed only in the conventional cake. It should be noted that a few nutty, brown, and potato type smells were detected in areas of the conventional cake chromatogram where no peaks were integrated. These aromas suggest the presence of other Maillard compounds in the extract at levels too low for instrumental detection. 

Wood pyrazine 3-ethyl-2- methoxy- 2-ethoxy- 3,6-dimethyl-3-ethyl- 2-propyl- 2-butyl-3,5- dimethyl- 2-butyl-3,6- dimefhyl- 2- acetyl- 3- methyl- 2-acetyl-3,5- dimethyl- Total... 

A special influence on the course of a reaction by a neighboring group is shown in the reactions of 5-acetyl-leuco(iso)alloxazines - with diazomethane. The methylation occurs neither in the pyrimidine nor in the pyrazine ring, but on the hydroxyl group of a newly formed oxazoline ring. For example,... 

Substituted perhydropyrido[l,2-a]pyrazine-l,4-diones were obtained when methyl A-[2-(benzyloxycarbonylamino)acetyl]-4-substituted pipecoli-nates were hydrogenated over 10% Pd/C catalyst in MeOH, and then the methanolic solutions were refluxed (00JAP(K)00/86659). 

Pyrazine, 2-ethyl-3-methyl Sd (roasted) ° Pyrazine, 2-ethyl-5-methyl Sd (roasted) ° Pyrazine, 2-ethyl-6-methyl Sd (roasted) ° Pyrazine, 3-5-dimethyl-2-(2 -furyl) Sd Pyrazine, 3-5-dimethyl-2-acetyl Sd Pyrazine, 3-6-dimethyl-2-(2 -furyl) Sd Pyrazine, 3-6-dimethyl-2-acetyl Sd Pyrazine, 3-ethyl-2-5-dimethyl Sd (roasted) " ... 

Two examples were reported for the synthesis of the pyrido[2,3-, ]pyrazine moiety using pyrazine precursors. Thus, amidation of methyl 2-aminopyrazine-3-carboxylate 670 with a substituted acetyl chloride followed by heterocycliza-tion of the formed amide 671 gave 6,8-dihydroxy pyridopyrazine 672 <2004W02004056825>. 

H NMR spectroscopy revealed that methyl cis-3H,9aH-2-acetyl- and 2-ferf-butoxycarbonylperhydropyrido[l,2-a]pyrazine-3-carboxylates exist a ca. 3.3 1 and ca. 1 1 mixtures of cis- and trans-amide rotamers, respectively, in CDCI3 solution (08SL702). 

N-Heterocycles Pyridine Pyrazines Unsubstituted, 2,3-Dimethyl, MARM ++ 2,5-Dimethyl-3-ethyl, Methyl, 2-Ethyl-6-methyl, 2,5-Dimethyl, 2-Ethyl-5-methyl, 2,6-Dimethyl, Acetylmethyl, 2-(2-Furyl), Ethyl, 2-Methyl-5-(methylethyl), Trimethyl Pyrroles 2-Acetyl, N-Methyl-2-furyl, 1-Formyl, 1-Furfury 1-2-formyl, 5-Methvl-2-formvl Trimethylpyrazine (TMPy) (RV = 0.989)... 

Treatment of imidazo[4,5-f>]pyrazine (225 R = H) with hydrogen peroxide in glacial acetic acid gave the 4-oxide (226 R = H) as the major product (50%) and the 4,7-dioxide (227 R = H) as the minor product. A 4-oxide was also obtained from the 1-methyl- and the l-(2,3,5-tri-0-acetyl-j8-D-ribofuranosyl)-imidazo[4,5-f)]pyrazine, in the latter case by means of MCPBA (73JMC643). Other 4-oxides and 4,7-dioxides have been prepared 75KGS690). 

Acetyl-2-carbamoyl-3-methyl-6-phenyl-2,5-dihydropyridazine (115) when heated with potassium hydroxide has been shown to give 2,5-diphenylpyrazine (497), and 2,6-dihydroxymorpholine (116) has been converted smoothly by hydrazine or hydroxylamine in aqueous hydrochloric acid to pyrazine in good yield (28). 

Extranuclear acetoxyalkylpyrazines have been prepared from hydroxyalkyl-pyrazines by acetylation with acetic anhydride and dry pyridine as follows 2-methyl-6-(D-flraho-tetraacetoxybutyl)pyrazine (182), 2,5-bis(D-araho-tetraacetoxybutyl)-pyrazine (182), and 2-acetoxymethyl-3-aminopyrazine (1075) and 2-methyI-5-(D-3-(D- 0 pyrazine with benzoyl chloride and dry pyridine (182). 

The Vilsmeier reaction on 2-methylpyrazine has been described in Section IV.2C(7) (717), and King s reaction on 2-methyl(and 23-dimethyl)pyrazine 1,4-dioxide has been described in Section IV.3C(7) (763). Pyrazine with A, jV-dimethyl-acetamide, ammonium peroxydisulfate, and ferrous sulfate gave 2-(A -acetyl-iV-methylaminomethyl)pyrazine (1188). 

The preparation of acetylpyrazines from cyanopyrazines and Grignard reagents proceeded in the usual manner. 2-Cyanopyrazine with methylmagnesium bromide in ether followed by treatment with dilute hydrochloric acid gave 2-acetylpyrazine (138, 1447). In a similar way the following pyrazines were prepared 2-acetyl-5-methyl (1327) 2-acetyl-6-methyl (1327) 5-acetyl-23-diphenyl (866) 2-acetyl-3,5,6-trimethyl (886) and 2-benzoyl (1447). 

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