Mesylate

In organosulfur chemistry, a mesylate is any salt or ester of methanesulfonic acid (CH₃SO₃H). In salts, the mesylate is present as the CH₃SO−3 anion. When modifying the international nonproprietary name of a pharmaceutical substance containing the group or anion, the spelling used is sometimes mesilate (as in imatinib mesilate, the mesylate salt of imatinib).^[1]

Mesylate anion (structural formula)

Mesylate anion (ball-and-stick model)

Mesylate esters are a group of organic compounds that share a common functional group with the general structure CH₃SO₂O−R, abbreviated MsO−R, where R is an organic substituent. Mesylate is considered a leaving group in nucleophilic substitution reactions.^[2]

Preparation

Mesylate esters are generally prepared by treating an alcohol and methanesulfonyl chloride in the presence of a base, such as triethylamine.^[3]

Mesyl

Related to mesylate is the mesyl (Ms) or methanesulfonyl (CH₃SO₂) functional group. Methanesulfonyl chloride is often referred to as mesyl chloride. Whereas mesylates are often hydrolytically labile, mesyl groups, when attached to nitrogen, are resistant to hydrolysis.^[4] This functional group appears in a variety of medications, particularly cardiac (antiarrhythmic) drugs, as a sulfonamide moiety. Examples include sotalol, ibutilide, sematilide, dronedarone, dofetilide, E-4031, and bitopertin.^{[citation needed]}

Natural occurrence

Ice core samples from a single spot in Antarctica were found to have tiny inclusions of magnesium methanesulfonate dodecahydrate. This natural phase is recognized as the mineral ernstburkeite. It is extremely rare.^[5][6]

See also

• Tosylate
• Triflate, the fluorinated analog of mesylate.

References

1. International Nonproprietary Names Modified (PDF) (Report). World Health Organization. February 2006. INN Working Document 05.167/3. Retrieved 5 December 2008.
2. Smith, Michael B.; March, Jerry (2007). March's Advanced Organic Chemistry (6th ed.). John Wiley & Sons. p. 497. ISBN 978-0-471-72091-1.
3. Rick L. Danheiser; Yeun-Min Tsai; David M. Fink (1966). "A General Method for the Synthesis of Allenylsilanes: 1-Methyl-1-(trimethylsilyl)allene". Organic Syntheses. doi:10.15227/orgsyn.066.0001. (a procedure illustrating the use of mesylates).
4. Valerie Vaillancourt, Michele M. Cudahy, Matthew M. Kreilein and Danielle L. Jacobs "Methanesulfonyl Chloride" in E-EROS Encyclopedia for Reagents in Organic Synthesis. doi:10.1002/047084289X.rm070.pub2
5. Güner, Fatma Elif Genceli; Sakurai, Toshimitsu; Hondoh, Takeo (2013). "Ernstburkeite, Mg(CH3SO3)2·12H2O, a new mineral from Antarctica". European Journal of Mineralogy. 25 (1): 78–83. Bibcode:2013EJMin..25...78G. doi:10.1127/0935-1221/2013/0025-2257.
6. Ernstburkeite, Mindat