Perchloric Acid → (S)-ethyl 2-tert-butoxy-2-(2-chloro-5-methyl-7-(trifluoromethylsulfonyloxy)benzo[d]thiazol-6-yl)acetate

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Reaction Steps

To a solution of (S)-ethyl 2-(2-chloro-5-methyl-7-(trifluoromethylsulfonyloxy)benzo[d]thiazol-6-yl)-2-hydroxyacetate (0.5691 g, 1.31 mmol) in tert-butyl acetate (65 mL) was added 70% perchloric acid (65 μL, 1.57 mmol). Reaction mixture was stirred for 1.5 h and quenched with solid sodium bicarbonate. Saturated sodium bicarbonate solution was carefully added until basic and mixture was extracted with ethyl acetate. The organic layer was washed with saturated sodium bicarbonate solution, brine, dried (MgSO4), filtered, concentrated and purified by CombiFlash (0 to 15% EtOAc/Hex) to give product contaminated with (S)-ethyl 2-tert-butoxy-2-(2-bromo-5-methyl-7-(trifluoromethylsulfonyloxy)benzo[d]thiazol-6-yl)acetate. 1H NMR (400 MHz, CDCl3): δ 7.78 (s, 1H), 5.59 (s, 1H), 4.4-4.1 (m, 2H), 2.55 (s, 3H), 1.20 (s, 9H), 1.16 (t, J=7.2 Hz, 3H).

Provenance & Evidence