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Synthesis 1996; 1996(12): 1477-1480
DOI: 10.1055/s-1996-4420
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Selective Monodeoxygenation of Methyl 3-(2-Quinoxalinylmethylene)carbazate N 1, N 4-Dioxide (Carbadox)

D. J. R. Massy, A. McKillop*
  • *School of Chemical Sciences, University of East Anglia, Norwich, NR4 7TJ, England, Fax +44(1603)507773; E-mail a.mckillop@uea.ac.uk
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Publication History

Publication Date:
31 December 2000 (online)

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The veterinary drug methyl 3-(2-quinoxalinylmethylene)carbazate N 1, N 4-dioxide (Carbadox) has been selectively reduced in good yield at either N 1 or N 4 with the reagents sodium dithionite or phosphorus trichloride, respectively. The identity of the products, which are important metabolites, was established by 1H NMR and by an X-ray crystal structure of the N 1-monodeoxygenated product. The further metabolite, bis(desoxy) Carbadox, was prepared by reduction of Carbadox with a slight excess of sodium dithionite/acetic acid. When a large excess of this reagent was used, a new compound, methyl 3-(2-quinoxalinylmethyl)carbazate, was also formed.

quinoxaline N-oxides - selective monodeoxygenation - Carbadox - veterinary drugs - metabolites - residues

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