Oxidation of Unsymmetrical Ketones using Selenium Dioxide I have searched the whole internet but I could only see examples where the authors of the article took $\ce{R1}$ and $\ce{R2}$ as the alkyl groups around the carbon. This is regarding the oxidation of carbonyl compounds (I am specifically searching about ketones) using $\ce{SeO2}$. What I understood was $\ce{C=O}$ got introduced on the alpha-carbon and two hydrogens from that carbon were lost. Please tell me the product obtained on reacting pentan-2-one with $\ce{SeO2}$. Will the carbon having 3 alpha-hydrogens become $\ce{C=O}$ or will the other one having 2 alpha hydrogens become $\ce{C=O}$?
References:

Selenium dioxide oxidation of ketones and aldehydes. Evidence for
the intermediacy of .beta.-ketoseleninic, K. Barry Sharpless and
Kenneth M. Gordon Journal of the American Chemical Society,
1976, 98 (1), 300-301 DOI: 10.1021/ja00417a083
https://www.adichemistry.com/organic/organicreagents/seo2/selenium-dioxide-seo2.html
The mechanism of Selenium Dioxide (Riley) oxidation proceeds via the enol tautomer of the ketone (see scheme - image from Wikipedia). If the ketone is assymetric and can enolise to either side then the reaction should give the two di-ketones in proportion to the amount of either enol formed though I cannot find any reference where this has been experimentally demonstrated. In the OP's case of 2-pentanone, a mixture of the two possible products will be formed.