Methanesulfonic Acid → (2R)-2-phenylcarbonyloxypropyl (2S)-2-amino-3-(3,4-dihydroxyphenyl)propanoate mesylate

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Reaction Steps

Methanesulfonic acid (3.9 mL, 60.1 mmol) was slowly added to a solution of (2R)-2-phenylcarbonyloxypropyl (2S)-2-(tert-butoxycarbonyl)amino-3-(3,4-dihydroxyphenyl)propanoate 1e (11.0 g, 22.1 mmol) in 1,4-dioxane (30 mL) while stirred at room temperature. The mixture was stirred for 2 h. The solution was slowly added to methyl tert-butyl ether (MTBE) (600 mL) with vigorous stirring. The resulting suspension was filtered. The filter cake was washed three times with methyl tort-butyl ether and air dried to afford 5.48 g (54% yield) of anhydrous mesylate salt 1 as an off-white solid.

Provenance & Evidence