Deoxygenation of pyridine N-oxides with dimethylthiocarbamoyl chloride

Journal of Heterocyclic Chemistry

Volumn 44, Issue 2, 2007, Pages 487-489

  Ponaras, Anthony A ^a   Zaim, Ömer ^b  

^a CATHOLIC UNIVERSITY OF AMERICA   (United States)

^b TRAKYA UNIVERSITY   (Turkey)

Author keywords

[No Author keywords available]

Indexed keywords

CHLORIDE; PYRIDINE DERIVATIVE;

ARTICLE; CHEMICAL STRUCTURE; CHROMATOGRAPHY; DEOXYGENATION; DISTILLATION; EVAPORATION; VACUUM;

EID: 36749025098     PISSN: 0022152X     EISSN: None     Source Type: Journal    
DOI: 10.1002/jhet.5570440236     Document Type: Article

References (30)

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6. A. R. Katritzky, J. M. Lagowski, Chemistry of the Heterocyclic N-Oxides, Academic Press, London and New York, 1971, pp 166-226.
7. Some recent deoxygenation methods are mentioned in ref [12] below.
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18. The N-oxides 4, 31, 35, and 39 are commercially available. Other N-oxides, 1, 7, 10, 13, 16, 19, 22, 25, 28 and 42 were prepared by treating the corresponding pyridines with 30% aqueous hydrogen peroxide in boiling acetic acid for 5 hours [1] and their properties were compared with the reported data.
19. A. A. Ponaras and Ö. Zaim, In The Encyclopedia of Reagents for Organic Synthesis, John Wiley; New York: 1993.
20. All yields given here refer to isolated yields, sometimes by distillation, more often by column chromatography.
21. All compounds were characterized by IR, NMR and MS.
22. Authentic samples of 3 and 6 were prepared via Newman-Kwart reactions [23,24] on 4-t-butyl-2-pyridone and 4-phenyl-2-pyridone, prepared by heating 1 and 4 with trifluoroacetic anhydride at 100°C in a sealed tube.
23. M. S. Newman and H. A. Karnes, J. Org. Chem., 31, 3980 (1966).
24. H. Kwart and E. R. Evans, J. Org. Chem., 31, 410 (1966).
25. Small amounts (<5%) of substances presumed to be the 6-dimethylcarbamoylthio isomers are also present.
26. We have prepared crystalline N-(dimethylthiocarbamoyloxy) pyridinium chlorides from 1, 4, 19 and 39 by mixing the pyridine N-oxides and DMTCC at room temperature in methylene chloride and then concentrating the solvent. These salts go on to products when heated in acetonitrile. The salt from pyridine N-oxide and DMTCC has been prepared and characterized but, apparently, has not been subjected to any further transformation: A. N. Pudovic, V. Y. Kovtun, V. K. Khairullin and M. A. Vasyanina, Zh. Obshch Khim., 62, 269 (1992).
27. For a discussion of some analogous processes which occur when pyridine N-oxides are treated with acylating agents such as acetic anhydride, see: [a] V. J. Traynelis, Mechanisms of Molecular Migrations; B. S. Thyagaragan, Ed.; 1969; Vol. 2, p 1;
28. [b] S. Tamagaki, S. Kozuka and S. Oae, Tetrahedron Lett., 4765 (1968) and references cited therein.
29. Our initial work, attempting to exploit a similarity between diosphenols and azaarene N-oxides (they are both subject to nucleophilic addition alpha to the oxy group), employed a combination of DMTCC and iodide ion (see ref. 9). It was later found that iodide ion is unnecessary. The deoxygenation of diosphenols with dimethylthiocarbamoyl chloride requires 2-equivalents of iodide ion: A. A. Ponaras,; Ö. Zaim,; Y. Pazo and L. Ohannesian, J. Org. Chem., 53, 1110 (1988)
30. We had previously suggested such intermediates (ref [19]).