93353-47-0Relevant academic research and scientific papers
Intermolecular character of the Fris rearrangement in the series of acyloxycoumarins
Kravchenko,Chibisova,Traven'
, p. 899 - 909 (2007/10/03)
In the study of the Fris rearrangement in the series of 7-and 4-acyloxycoumarins we obtained certain data indicating intermolecular character of the rearrangement. The Fris rearrangement of a mixture of 7-benzoyloxy-4-metylcoumarin and 7-acetoxycoumarin results in formation of four reaction products in approximately equal molar ratio. Also, four products were obtained in the Fris rearrangement of 7-and 4-acyloxycoumarins in the presence of hydroxycoumarins. The Fris rearrangement of acyloxycoumarins in the presence of m-xylene at acylcoumarin-m-xylene ratio of 1:6 leads to the corresponding hydroxycoumarins and acylated m-xylenes. Intermediate formation of acylium ions was also detected by evolution of carbon monooxide at the Fris rearrangement of 7-pyvaloyloxy-and 7-isobutyryloxy-4-methylcoumarins. A product of intermolecular migration, 3-acetyl-4-hydoxy-6-methylcoumarin, was discovered also in the rearrangement of 4-acetoxycoumarin in the presence of 4-hydoxy-6-methylcoumarin catalyzed by phosphorus oxychloride.
