2H-1-Benzopyran-6-sulfonyl chloride, 3,4-dihydro-2-oxo- synthesis

Yield:-

Reaction Conditions:

with chlorosulfonic acid at 0 - 20; for 2.33333 h;

Steps:

192.1

To chlorosulfonic acid (3.5 mL) at 0° C. was added dihydrocoumarin (4.5 g, 3.84 mL, 30 mmol) via addition funnel dropwise over 20 minutes. After the addition was complete, the reaction mixture was warmed up to room temperature and stirred for 2 h. The mixture was carefully poured over ice water. The resulting emulsion was rinsed into a separatory funnel and extracted with ethyl acetate (3×50 mL), dried over Na₂SO₄ and concentrated in vacuo to give the title compound (3.2 g 43%). This material was used directly without further purification. ¹H NMR (400 MHz, CDCl₃) δ 7.99-7.94 (m, 2H), 7.28-7.26 (m, 1H), 3.16 (t, 2H), 2.89 (dd, 2H).

References:

US2005/234046,2005,A1 Location in patent:Page/Page column 93