Thiophosgene → 4-Bromo-7-fluorobenzo[d][1,3]dioxole-2-thione

Participants

Reaction Conditions

Reaction Steps

3-Bromo-6-fluorobenzene-1,2-diol (8.9 g, 43 mmol) was dissolved in chloroform (100 mL), cooled to 0-5° C. and treated with thiophosgene (5.4 g, 47 mmol). Aqueous sodium hydroxide solution (10 wt %; 40 g, 99 mmol) was added in portions over 30 min with vigorous stirring. Stirring was continued for 60 min at 5-15° C. and then most of the chloroform was removed by rotary evaporation. The pH was adjusted to 2 by addition of 1 M HCl and the precipitated thione was taken up in ethyl acetate (150 mL). The organic phase was washed with water (25 mL), saturated NaCl (25 mL), dried (Na2SO4), and evaporated. The crude product was purified by flash chromatography, eluting with a 0-20% ethyl acetate-hexane gradient to give the title compound as a tan solid (6.2 g, 58%): mp 72-76° C.; 1H NMR (400 MHz, CDCl3) δ 7.40 (dd, J=9.2, 4.1 Hz, 1H), 7.04 (t, J=9.1 Hz, 1H); 19F NMR (376 MHz, CDCl3) δ −132.68; EIMS m/z 248.

Provenance & Evidence