Methylpyrazine 1-oxides with benzaldehyde

Methylpyrazine 1-oxides react with benzaldehyde to give styrylpyrazine 1-oxides. Thus tetramethylpyrazine 1,4-dioxide, p-dimethylaminobenzaldehyde, and 37% hydrochloric acid at 140° for 15 hours gave 2,3,5,6-tetra(p-dimethyIaminostyryl)-pyrazine 1,4-dioxide (713) 2,5-dimethylpyrazine 1,4-dioxide, benzaldehyde, and sodium hydroxide gave 2,5-distyrylpyrazine 1,4-dioxide, and 2,5-dimethylpyrazine... 

The sodio derivative of methylpyrazine (20) reacts with aldehydes and ketones to give secondary and tertiary pyrazine carbinols, respectively.175, 178 Yields in the range 21-99% are obtained when the molar ratio of methylpyrazine sodamide carbonyl compound used is 2 2 1. Oppenauer oxidation of 1-phenyl-2-pyrazylethand (21), the aldol addition product of methylpyrazine and benzaldehyde, gives phenacylpyrazine (22) in 18% yield.176... 

Cyanopyrazine reacts with cyclopropyllithium to give pyrazinyl cyclopropyl ketone <91JHC1147>. Benzoyl pyrazine is formed by oxidative decyanation of a-pyrazinyl-a-phenylacetonitrile under phase-transfer catalytic conditions <87JHC1061 >. (2-Hydroxy-2-phenylethyl)pyrazines undergo retro-ene reaction on pyrolysis to yield methylpyrazines and benzaldehyde quantitatively <87JOC397i>. 

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See also in sourсe #XX -- [ ]

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