Selenium assisted carbonylation of alkyl aryl ketones with carbon monoxide

Selenium assisted carbonylation of alkyl aryl ketones with carbon monoxide leading to formation of 1,3-dicarbonyl compounds as C-carbonylated products is described. o-Hydroxyacetophenone 7a and its derivatives7b,7c, and 7d have been converted to the corresponding 4-hydroxycoumarins 8a,8b,8c and 8d in moderate to quantitative yields by treatment with an equivalent of selenium and carbon monoxide with concomitant formation of hydrogen selenide 9 (Eq.(8)). It was further revealed that oxidation of in situ formed hydrogen selenide to selenium with an appropriate oxidizing agent such as nitrobenzene permitted catalytic use of selenium for the carbonylation of 7. Possible rationalizations for the formation of 4-hydroxycoumarins are suggested.