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|Title:||Studies on the synthesis of 2-phenylsulphonyl-3-styrylquinoxalines|
|Authors:||Krishnan, V S H|
Chowdary, K S
Dubey, P K
|Abstract:||o-Phenylenediamine 1 is condensed with pyruvic acid or sodium pyruvate to yield 3-methylbenzo-1H-dihydropyrazine-2-one 2. The latter on condcnsation with aromatic aldehydes give 3-styrylquinoxaline-1H-2-one 3. Reaction of 3 with POCl3 in the presence of catalytic amount of DMF yields 2-chloro-3-styrylquinoxaline 4, which on reaction with thiophenol in the presence of triethylamine in methanol gives 2-phenylthio-3-styrylquinoxaline 5. Oxidation of 5 with H2O2 in the presence of acetic anhydride affords 2-phenylsulphonyl-3-styrylquinoxaline 6. 6 has also been prepared directly from 4 by reaction with sodium benzenesulphinate under phase transfer conditions. In an alternate approach to the synthesis of title compound, 2 is treated with POCl3 in DMF to obtain the known 2-chloro-3-methylquinoxaline 7. Reaction of 7 with thiophenol in the presence of triethylamine in methanol gives 2-methyl-3-phenylthioquinoxaline 8. Oxidation of 8 with H2O2 in Ac2O affords 2-methyl-3-phenylsulphonylquinoxaline 9. 9 was also prepared in an alternate method from 7 by reaction with sodium benzenesulphinate. 9 on reaction with aromatic aldehydes yields the title compounds 6.|
|Appears in Collections:||IJC-B Vol.40B(07) [July 2001]|
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