p-Toluenesulfonic acid → 2-(2-Oxo-3-buten-4-yl)-5-chloro-4-isothiazolin-3-one

Participants

Reaction Steps

A stirred solution of 5-chloro-3-hydroxyisothiazole (1.5 g, 0.011 mole), 1-butyn-3-one (3.5 g, 0.05 mole) and p-toluenesulfonic acid (0.02 g) in 25 ml of toluene was heated at 80° C. for 24 hours. Upon cooling, the dark brown reaction mixture was concentrated and the residual oil was column chromatographed on silica gel, using diethyl ether/hexane as eluant. Compound 11 was obtained as a yellowish solid; 1.8 g; mp 137°-139° C.; IR (KBr) 1675, 1620 cm-1 ; NMR (CDCl3) δ8.2 (d, 1H, J=13.9 Hz); 6.35 (s, 1H); 5.85 (d, 1H, J=13.9 Hz); 2.35 (s, 3H).

Provenance & Evidence