If I get 2,9-dialdehyde-1,10-phenanthroline from 2,9-dimethyl-1,10-phenanthroline by oxidizing with SeO2, why it is not possible for 5,5'-dicaldehyde-2,2'-bipyridine from 5,5'-dimethyl-2,2'-bipyridine ??
Hoq
You have the answer already 2,9-dimethyl-1,10-phenanthroline can be oxidized [ methyl carbon is alpha to C=N] thus you can oxidize 6,6'-dimethyl-2,2'-bipyridine which has been already reported. See
---Newkome, George R. and Lee, H. W. Journal of the American Chemical Society, 105(18), 5956-7; 1983.
On the other hand 5,5'-dimethyl-2,2'-bipyridine could be oxidized to its corresponding 5,5'-dicarbaldehyde by two steps; enamination of 5,5'-dimethyl-2,2'-bipyridine with Bredereck's reagent, and subsequent oxidative cleavage of the enamine groups with sodium periodate. See
---Hodacova, Jana; Budesinsky, Milos, Organic Letters, 9(26), 5641-5643; 2007.
Good luck
Thanks amer...As mechanism shows that it can Oxidize C=C- CH3, why I cant 5,5-dimthyl-2,2' pyridine.? Thanks for your reply again
Hoq
quote from the site "Selenium dioxide, SeO2 is an oxidizing agent generally employed in the allylic oxidation of alkenes to furnish allylic alcohols, which may be further oxidized to conjugated aldehydes or ketones" NOT METHYLARENE !
From the mechanism, the re-arrangement of the C=C in case of methylarene will be difficult due to the stability [aromaticity of the ring and SeO2 is not E+ !] on the other hand the polarity of C=N in case of methylheteroarene [containing the N] would initiate the attach of the N atom to Se thus such re-arrangement could be possible.
Hope that is clear enough.
Good luck
The methyl groups in bipyridyl adjacent to nitrogen atoms and it exist in a tautamerism ( H2C=C-NH ) as in methyl picoline
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