182115-42-0

Upstream product

• 90-33-5 7-hydroxy-4-methyl-chromen-2-one 
• 182115-37-3 2-oxo-2H-chromen-7-yl chloroethanoate 
• 108-38-3 m-xylene 
• 108-67-8 1,3,5-trimethyl-benzene 
• 93-35-6 7-hydroxy-2H-chromen-2-one 
• 105738-24-7 7-chloroacetyloxy-4-methylcoumarin 

Relevant academic research and scientific papers

Intermolecular character of the Fris rearrangement in the series of acyloxycoumarins

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.