CH3OTf

CH3OTf, commonly referred to as methyl triflate or methyl trifluoromethanesulfonate, is a colorless, volatile, and moisture-sensitive organosulfur compound that serves as a powerful methylating agent in organic synthesis. Its high reactivity stems from the triflate leaving group, which makes CH3OTf one of the most effective methyl donors available for many substrates.

Structure and properties: The molecule consists of a methyl group linked through an ether to the triflate group (CF3SO3). Its chemical formula is C2H3FO3S. CH3OTf is typically a liquid at room temperature and is highly reactive toward nucleophiles such as amines, alcohols, and thiols. It hydrolyzes readily in the presence of water to methanol and triflic acid (HOTf).

Preparation and handling: Commercial methyl triflate is usually prepared in situ by reacting methanol with triflic anhydride or by using suitable triflate sources in dry organic solvents. In practice, it is handled under dry, inert conditions and often as a solution in an organic solvent. It must be stored in tightly closed, moisture-free containers in a dedicated fume hood due to its moisture sensitivity and corrosive nature. Contact with water or air can generate heat and corrosive byproducts.

Applications: CH3OTf is employed to methylate a wide range of substrates, including converting alcohols to methyl ethers and N- or O-methylating amines, thiols, and other nucleophiles. It is also used in carbohydrate and glycoside chemistry to activate or protect hydroxyl groups. Because of its extreme reactivity, CH3OTf is generally used with careful control of moisture and reaction conditions, and often in small-scale or specialized synthetic settings. Safety considerations are essential due to its strong electrophilicity and corrosive potential.