2- 2- propionyl pyrazine

Chloro-3-propionylpyrazine (164, R = Cl) gave 2-ethylthio-3-propionyl-pyrazine (164, R = SEt) (EtSH, EtONa, EtOH, 20°C, 4 h 87%).815... 

Heating either trimethyl 2-methyl-6-ethylidene-2,6-dihydro-l//-pyrido[l,2a]-pyrazine-7,8,9-tricarboxylate or tetramethyl 1,2-dimethyl-2,9a-dihydro-l//-pyrido-[l,2-a]pyrazine-6,7,8,9-tetracarboxylate in dilute HC1 gave dimethyl 2-methyl-7-propionyl-l,6-dioxo-2,6-dihydro-l//-pyrido[l,2-a]pyrazine-8,9-dicarboxylates (62JCS1510). 1,12-Dihydroxyper-hydrodibenzo[ac]pyrazine was prepared from l-(2-tetrahydrofuryl)-9-hydroxyperhydropyrido[l,2-a]pyrazine in AC2O saturated with HBr at 95-100°C (61BSF2135). 

Note The Rh-catalyzed C-acylation of reduced pyrazines with carbon monoxide and ethylene appears to offer considerable potential for further development. l-Methyl-4-(pyridin-2-yl)piperazine (292) gave l-methyl-3-propionyl-4-(pyridin-2-yl)-l,4,5,6-tetrahydropyrazine (293) [Rh4(CO)12, PhMe, H2C=CH2 J, to 10 atm, CO l to 15 atm, 25°C, autoclave then 160°C, 20 h 85%] several N-alkyl/aryl homologues were made similarly.1404... 

Amino-6-(prop-l-enyl)-2-pyrazine-carbothioamide 4-oxide 3-Amino-6-(prop-l-enyl)-5-thioxo-4,5-dihydro-2-pyrazinecarbonitrile 3-Amino-5-propionyl-2-pyrazinecarbonitrile 3-Amino-5-propionyl-2-pyrazinecarboxamide 3-Amino-6-propoxymethyl-2-pyrazine-carbonitrile... 

Ethyl-3-piperidinopyrazine Ethyl 6-piperidino-2-pyrazinecarboxylate Ethyl 5-propionyl-2-pyrazinecarboxylate 2-(l-Ethylpropyl)pyrazine... 

Acyl derivatives of perhydro-l,4-dioxopyrrolo[l,2-a]pyrazines are rapidly hydrolyzed to the 2-unsubstituted compounds under very mild conditions. The 2-pyruvoyl compound 86 loses the N-acyl group on boiling in water or methanol, on treatment with ammonia in methylene chloride, on exposure to dilute sodium hydroxide solution, and on treatment with p-toluidine at 50-60° for 30 sec. Similarly the methoxy-propionyl compound 142 is extremely sensitive to alkali, immediately reacting with 0.1 M sodium hydroxide solution at 0°. This compound is also deacylated by ammonium hydroxide solution in a few minutes or by sodium bicarbonate solution after several hours. This behavior contrasts sharply with that of the isomeric oxazolo compound 143 and helps to justify the tricyclic formulation adopted for such compounds. Hydrolysis of the 3S,8aS isomer of compound 142 is accompanied by rapid inversion... 

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