Pyrido pyrazinium salts

No systematic study of the mass spectra of pyridopyrazines has been noted, but those of 2,3-dialkyl and 2,3-diaryl derivatives have been recorded 750MS97), and mass spectrometry has been used in the elucidation of problems in the reactions of pyrido[2,3-f ]pyrazines with amide ion (including use of and derivatives) (79JHC305), and of pyrido[2,3-f ]pyrazinium salts with indoles (78ZOR431). The mass spectra of some 1-deazaflavins have been recorded (74JCS(P1)1965). 

Substituted pyrido[2,3-(i]pyrazinium salts form cycloadducts with quinones (75HCA2529), similar to those formed by quinoxalinium salts. 

Pyrido[l,2-a]pyrazin-5-ium salts — see 2-Azaquinolizinium salts E rido[2,3-b]pyrazinium salts mass spectra, 3, 250... 

Pyrido[2,3-b]pyrazinium salts, N-aryl-2,3-dimethyl-nucleophilic attack, 3, 253 Pyrido[2,3-(i]pyrazinium salts reactions... 

Pyrazine diquatemary salts of types 16lB1 and 17152 are known and also 6,7-dihydro derivatives of 16.152a The diquaternary salt (17) was originally formulated as the monohydrate of 18, but attempts to dehydrate 17 to 18 have not been successful.152 Dipyrido[l,2-a 2, l -c]pyrazinium dibromide (16) has herbicidal properties it is reduced in aqueous solution to a stable radical cation.183 The related pyrido[l,2-a]pyrazinium salts of type 19 have also been prepared.153,1B4a... 

Various 1,5-diketones of type 30 have been cyclized using ammonium acetate in acetic acid to give 1,3-disubstituted pyrido[l,2-a]pyrazinium salts (31). Similar treatment of the ester 32 gave the oxo compound 33. 

The lipophilicity (7 m value) and specific hydrophobic surface area of pyrido[l,2-a]pyrazinium-l-olates 342 and -3-olate 343, and l-(4-chlorophe-nyl)-l-hydroxy-l,2-dihydropyrazino[2,l-a]isoquinolinium salt (344) has been measured by reversed-phase thin-layer chromatography (98MI13). Partition coefficient (log/ ) of 9-bromo-5-[(A-phenylaminocarbonyl)-methyl]-l,2,3,5,6,7-hexahydropyrido[l,2,3- fc]quinoxaline-2,3-dione was calculated to be 2.78 (97JMC4053). 

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