Partial methyl ethers of polyhydroxy coumarins - Part I. Partial methylation of 5∶7-dihydroxy-4-methyl coumarin
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Earlier investigations have shown that partial methylation of the 7-position of 6∶7-dihydroxy coumarin is definitely possible. Claims were made by Schmid that in 5∶7-dihydroxy-4-methyl coumarin also partial methylation takes place in the 7-position. But no proof was provided. This has now been given by the ethylation of the partial methyl ether and subjecting it to nuclear oxidation and final ethylation. The product is found to be 7-methoxy-5∶6-diethoxy-4-methyl coumarin which has also been made by an independent and unambiguous method for purposes of comparison. The constitution of the partial methyl ether is thus established as 7-methoxy-5-hydroxy-4-methyl coumarin.