Thionyl Chloride → 1-(Trifluoroacetyl)-2,3-dihydro-1H-indole-5-sulfonyl chloride

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Reaction Steps

Chlorosulfonic acid (13.3 mL, 200 mmol, 2.00 equiv) was added to a solution of 1-(trifluoroacetyl)indoline (1-5, 21.5 g, 99.9 mmol, 1 equiv)) in thionyl chloride (65.6 mL, 899 mmol, 9.00 equiv) precooled to 0° C. The resulting mixture was stirred for 50 minutes, then poured onto ice (approx. 3 kg). The precipitate was filtered and then dried in vacuo to afford 1-(trifluoroacetyl)indoline-5-sulfonyl chloride (1-6) as an orange solid. 1H NMR (500 MHz, CDCl3) δ 8.42 (d, 1H, J=8.5 Hz), 8.00 (d, 1H, J=6.7 Hz), 7.92 (s, 1H), 4.43 (t, 2H, J=8.2 Hz), 3.41 (t, 2H, J=8.2 Hz).

Provenance & Evidence