2.3- Dicyano-5,6-dimethylpyrazine

Irradiation of a mixture of 2,3-dicyano-5,6-dimethylpyrazine 85 and allylic silanes leads to the formation of 2,8-diazatricyclo[3.2.1]oct-2-enes 86 via [2-I-2] photocyclization followed by rearrangement (Equation 12)... 

Mono- and disubstituted N-alkyl and N-arylaziridines are reported to undergo a photoinduced electron transfer [3+2] cycloaddition to dipolarophiles to produce five-membered heterocycles, and it is suggested that in this process the radical cation intermediate behaves differently from the corresponding classical azomethine ylide. Intramolecular [4+4] photocycloaddition of the dipyridyl-propane (73) followed by Li/NHa reduction is a useful route to the eleven-membered ring system (74), and on irradiation of benzene solutions of 2,3-dicyano-5,6-dimethylpyrazine in the presence of allylic silanes a [2+2] cyclisation is induced followed by rearrangement to give 2,8-diazatricyclo[3.2.1.0 ]oct-2-ene (75 R = H, Me). ... 

Dicyano-3,6-dimethylpyrazine shaken with sodium ethoxide at room temperature for 10 hours produced 2-cyano-5-ethoxy-3,6-dimethylpyrazine (288). Bromination of 2-methoxy-3-sulfanilamidopyrazine (39) in methanol led to 5-(4 -amino-3, 5 -dibromobenzenesulfonimido)-6-hydroxy-2,3-dimethoxy-2,3,4,5-tetrahydropyrazine (32) which with 2 N sodium hydroxide gave 3-(4 -amino-3, 5 -dibromobenzenesulfonamido)-2-hydroxy-5 nethoxypyrazine (40) (816). The preparation of 2-amino-3,5-dicyano-6-methoxy(and ethoxy)pyrazine from a-(p-toluenesulfonyloxyiminomalononitrile and malononitrile has been described in Section II.7 (484). 2-Methoxycarbonyl(and cyano)-5-pyridiniopyrazine chloride (41) is reported (conditions not stated) to give 2-carboxy(and carbamoyl)-5-methoxypyrazine (765). 

Methylation (666, 912) of 2-methoxypyrazine with methyl iodide in dimethyl sulfoxide at room temperature gave 3-methoxy-l-methylpyrazinium iodide with a rate of methylation relative to pyrazine of 1.05 (666). 2-Methoxypyrazine with tetracyanoethylene oxide gave a small yield of 3 ethoxypyrazinium dicyano-methylide (53) (1094). Alkylation of 2-methoxypyrazine with ethyl methyl ketone in the presence of sodium in liquid ammonia to give 2-s-butyl-6-methoxypyrazine (17%) has been described (614). The reactions of 3-hydroxy-2,5-dimethylpyrazine and alkylhalides have been examined (1095). 

Dicyano-3,6-dimethylpyrazine shaken with sodium ethoxide at room temperature gave 2-cyano-5-ethoxy-3,6-dimethylpyrazine and 2-cyano-5-hydroxy-3,6-dimethylpyrazine (288). Reactions of 2-chloro-6-cyanopyrazine with sodium methoxide have been described in Sections 1 A(2)(c). 

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