Methoxy group

On a benzene ring, the Hammett equation classifies a methoxy substituent at the para position as an electron-donating group, but as an electron-withdrawing group if at the meta position.

Many metal alkoxides contain methoxy groups, such as tetramethyl orthosilicate and titanium methoxide.

[1] In nature, methoxy groups are found on nucleosides that have been subjected to 2′-O-methylation, for example in variations of the 5′-cap structure known as cap-1 and cap-2.

They are also common substituents in O-methylated flavonoids, whose formation is catalyzed by O-methyltransferases that act on phenols, such as catechol-O-methyl transferase (COMT).

Many natural products in plants, such as lignins, are generated via catalysis by caffeoyl-CoA O-methyltransferase.