Methoxy

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The structure of a typical methoxy group.

In chemistry (particularly organic chemistry), methoxy refers to the functional group consisting of a methyl group bound to oxygen. This alkoxy group has the formula OCH3. The term is used in organic chemistry usually to describe an ether. As quantified by the Hammett equation, methoxy is an electron-donating group.

Occurrence[edit]

The simplest methoxy compounds are methanol and dimethyl ether. Other methoxy ethers include anisole and vanillin. Many metal alkoxides contain methoxy groups, e.g. tetramethyl orthosilicate and titanium methoxide. Such compounds are often classified as methoxides.

Biosynthesis[edit]

In Nature, methoxy compounds are notable by their absence. They do not occur in amino acids, the heterocycles that comprise the genetic code, nor in lipids. They are however common substituents in O-methylated flavonoids. Their biosynthesis entails O-methyltransferases, which act on phenols, e.g., Catechol-O-methyl transferase. A large number of natural products in plants, e.g. lignins, are generated via catalysis by caffeoyl-CoA O-methyltransferase ("COMT").[1]

Methoxylation[edit]

Commonly organic methoxides are derived by methylation of alkoxides.[2][3]

Some aryl methoxides are available via metal-catalyzed methylation of phenols, or as well methoxylation of aromatic halogenides.[4][5]

References[edit]

  1. ^ Wout Boerjan, John Ralph, Marie Baucher "Lignin Biosynthesis" Annu. Rev. Plant Biol. 2003, vol. 54, pp. 519–46. doi:10.1146/annurev.arplant.54.031902.134938
  2. ^ J. A. Scarrow and C. F. H. Allen "Methoxyacetonitrile" Org. Synth. 1933, 13, 56.doi:10.15227/orgsyn.013.0056
  3. ^ Josep Cornella, Cayetana Zarate, and Ruben Martin "Ni-catalyzed Reductive Cleavage of Methyl 3-Methoxy-2-Naphthoate" Org. Synth. 2014, 91, 260. doi:10.15227/orgsyn.091.0260
  4. ^ Cheung, Chi Wai; Buchwald, Stephen L. (2 August 2013). "Mild and General Palladium-Catalyzed Synthesis of Methyl Aryl Ethers Enabled by the Use of a Palladacycle Precatalyst". Organic Letters 15 (15): 3998–4001. doi:10.1021/ol401796v. 
  5. ^ Tolnai, Gergely L.; Pethő, Bálint; Králl, Péter; Novák, Zoltán (13 January 2014). "Palladium-Catalyzed Methoxylation of Aromatic Chlorides with Borate Salts". Advanced Synthesis & Catalysis 356 (1): 125–129. doi:10.1002/adsc.201300687.