6- Chloro-2-pyrazinecarbonyl chloride

Chloro-2-pyrazinecarbonyl chloride (140, R = Cl) and AKcyclopent- 1-en-1-yl)pyrrolidine gave 2-chloro-3-[2-(pyrrolidin-1 -yl)cyclopent-l-en-1 -ylcar-bonyl]pyrazine (141) (Et3N, CH2C12,--------40°C, N2, 2 h 63%).382... [Pg.320]

The most convenient synthesis of halogenopyrazines and -quinoxalines is by halogenation of pyrazinones and quinoxalinones with phosphoryl or other acid halides for example, 5-hydroxy-2-pyrazinecarboxylic acid, rather than 5(477)-pyrazinone-2-carboxylic acid, is chlorinated with phosphorus pentachloride/phosphoryl chloride to afford a 63% yield of 5-chloro-2-pyrazinecarbonyl chloride <1994SL814>. Sato and Narita provided an improved synthesis of various halogenopyrazines in which 2(l//)-pyrazinones were activated with chlorotrimethylsilane to give silyl ethers (Section 8.03.7.3). This procedure is most effective for synthesis of bromopyrazines whose overall yields are 62-81% <1999JHC783>. Bromopyrazine is directly prepared by treatment of 2-(l//)-pyrazinone with phosphoryl... [Pg.317]

Chloro-2-pyrazinecarboxyhc acid (28, R = Cl) gave 6-chloro-2-pyrazinecar-bonyl chloride (29, R = Cl) (SOCl2, PhH, reflux, 90 min 73%) 505 and 6-phenyl-2-pyrazinecarboxylic acid (28, R = Ph) gave 6-phenyl-2-pyrazinecarbonyl chloride (29, R = Ph) (neat SOCl2, reflux, 2 h uncharacterized product).1015... [Pg.304]

Chloro-2-pyrazinecarbonyl chloride (126) and 2-pyrazinamine gave 6-chloro-Ar-(pyrazin-2-yl)-2-pyrazinecarboxamide (127) (Et3N, PhH, 20°C, 30 min 85%).505... [Pg.318]

Pyrazinedicarbonyl dichloride (144) and cyclohexyl isocyanate gave 3-[a-chloro-a-(cyclohexylimino)acetyl]-2-pyrazinecarbonyl chloride (145) (PhH, 20°C, 1 h then 60°C, 45 min 54%).523 Also other examples.275 1091... [Pg.320]

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