Ethylene Glycol → 2,4-Dichloro-5-(1,3-dioxolan-2-yl)-1,3-thiazole

Participants

Reaction Steps

Add p-toluenesulfonic acid monohydrate (1.70 g, 8.94 mmol) to a stirred solution of 2,4-dichloro-thiazole-5-carbaldehyde (21.05 g, 116 mmol), ethylene glycol (20.0 mL, 359 mmol), and anhydrous toluene (300 mL). Add a Dean-Stark trap and heat the reaction to reflux under nitrogen for 7 h. Cool the reaction and pour it into 10% sodium carbonate (300 mL). Extract with ethyl acetate (3×150 mL) and wash with brine (150 mL). Dry the ethyl acetate over sodium sulfate and then filter off the sodium sulfate. Concentrate on a rotary evaporator and purify the crude product by flash chromatography on silica gel eluting with 10% ethyl acetate/hexanes to yield 24.77 g (95%) of 2,4-dichloro-5-[1,3]dioxolan-2-yl-thiazole: mass spectrum (ion spray): m/z=225.9 (M+1); 1H NMR (CDCl3): δ=6.08 (s, 1H), 4.19-4.03 (m, 4H).

Provenance & Evidence