Pyridine → Methyl 2-trifluoromethanesulfonyloxy-1-naphthoate

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Reaction Steps

Trifluoromethanesulfonic anhydride (492 g, 1.74 mol, 1.1 eq) in dichloromethane (0.5 L) was added over 1.5 hours to a suspension of methyl 2-hydroxy-1-naphthoate (319 g, 1.58 mol) and pyridine (330 ml, 4.08 mol, 2.6 eq) in dichloromethane (1.7 L) maintained at an internal temperature between −70 and −50° C., under nitrogen. Once the addition was complete, the mixture was allowed to warm to ambient temperature and stirred for 16 hours, after which time all solids had dissolved. Methyl tert-butyl ether (MTBE, 2.5 L) was added, causing precipitation. The solids were removed by filtration and washed with MTBE (0.5 L). The MTBE solutions were combined and washed with 2 N HCl(aq) (0.3 L then 0.2 L), water (2×2.5 L) and brine (2 L). The organic layer was dried (MgSO4), filtered and concentrated under reduced pressure. The residue was dissolved in toluene (2.5 L) and washed with 1 N NaOH (aq) (0.5 L), water (2.5 L) and brine (1 L). The toluene solution was dried (MgSO4), filtered and concentrated under reduced pressure. Initially a slightly brown oil, the product crystallised on standing. Yield 438.5 g, 83%

Provenance & Evidence