2-Chloro-3-hydroxy-5,6-diphenylpyrazine with phosphoryl chloride

Whereas 2-hydroxy-3-nitro-5,6-diphenylpyrazine with phosphoryl chloride at reflux has been shown to give a mixture of 2-chloro-3-hydroxy- and 2,3-dichloro-... 

Chloro-2,S-dimethylpyrazine was not isolated from the reaction of DL-alanine anhydride with a mixture of phosphoryl chloride and phosphorus pentachloride, but the reaction gives a poor yield of (48, X = Q) and a small quantity of (48, X = OH). Gallagher et al. (282) found that DL-phenylglycine with phosphoryl chloride gave 2,5-dichloro-3,6-diphenylpyrazine and 3-hydroxy-2,5-diphenyl-pyrazine (presumably formed by loss of the elements of hydrogen chloride from an intermediate 2-chloro-5-hydroxy-3,6-diphenyldihydropyrazine) and Dunn et al. (95) from DL-leucine anhydride and phosphoryl chloride prepared flavacol, 3-hydroxy-2,5-diisobutylpyrazine, and a mature of chloropyrazines, whereas Ohta (101) used phosphoryl chloride and phosphorus pentachloride and obtained flavacol and a little 2[Pg.26]

Chloro-3-methylpyrazine (101,535) and 2-chloro-5-phenylpyrazine (363, 365a, 377, 824, 825) have been prepared from the corresponding hydroxy compound and phosphoryl chloride, 2-chloro-6-methylpyrazine from 2-hydroxy-6-methylpyrazine and phosphoryl chloride with one drop of dimethylformamide (681), and 2-benzyl(or s-butyl, isobutyl, or isopropyl)-3phosphoryl chloride with a trace of concentrated sulfuric acid (80). 2-Chloro-6-methyl-3-propyl- (826), 3[Pg.99]

Many derivatives of carboxy chloropyrazines have been prepared by the action of phosphoryl chloride on the corresponding hydroxypyrazine. In this way were prepared 2-chloro-3-methoxycarbonylpyrazine (371, 423, 836), 2-chloro-3-methoxycarbonyl-5,6-diphenylpyrazine (but the corresponding hydroxy compound did not react with phosphorus tribromide) (837), and 3-chloro-2-methoxycarbonyl-... 

The reactions of phosphoryl chloride and some hydroxypyrazine A-oxides with an unsubstituted position adjacent to the A-oxide function to give chlorohydroxy-pyrazines have been described in Section V.IG. In this way 3-hydroxy-2,5-diisobutylpyrazine 1-oxide was converted to 2-chloro-5-hydroxy-3,6-diisobutyl-pyrazine (101) and 2-hydroxy-3,5-diphenylpyrazine 1-oxide gave 2-chloro-6-hydroxy-3,5-diphenylpyrazine (873). 

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