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

Participants

Reaction Steps

Ethylene glycol (7.0 ml, 125.5 mmol) and p-toluenesulfonic acid monohydrate (0.56 g, 2.94 mmol) are added to a solution of 2,4-dichloro-thiazole-5-carboxaldehyde (7.88 g, 43.3 mmol) in toluene (100 ml). The reaction is heated at reflux and water removed via Dean-Stark for 4 h. The reaction is cooled, poured into 20% Na2CO3 (200 ml), and extracted with ethyl acetate (3×100 ml). The ethyl acetate is washed with aqueous saturated brine solution and dried over anhydrous Na2SO4. The solid is filtered off and the filtrate concentrated. The crude product is purified by flash chromatography on silica gel eluting with 10% ethyl acetate/hexanes to yield (9.42 g, 96%) of 2,4-dichloro-5-([1,3]dioxolan-2-yl)-thiazole: 1H NMR (CDCl3): δ=6.07 (1H, s), 4.18-3.99 (4H, m).

Provenance & Evidence