In chemistry, a mesylate is any salt or ester of methanesulfonic acid (CH3SO3H). In salts, the mesylate is present as the CH3SO3− anion. When modifying the International Nonproprietary Name of a pharmaceutical substance containing the group or anion, the correct spelling is mesilate (as in imatinib mesilate, the mesylate salt of imatinib).[1]
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 an excellent leaving group in nucleophilic substitution reactions.
Mesyl is the term for the methanesulfonyl or CH3SO2- (Ms-) functional group. For example, methanesulfonyl chloride is often referred to as mesyl chloride.
Mesylates may be prepared using an alcohol and methanesulfonyl chloride in the presence of a base, often amine bases such as triethylamine.[2] Mesylates can also be prepared by combining an alcohol, methanesulfonic anhydride and base, although this method is generally used only if the nucleophilicity of chloride is a concern.