Hydrochloric Acid → 3-Methoxythiophene-2-carbaldehyde

3-Methoxy-2-thiophenecarboxadlehyde was prepared by adding n-butyllithium (10.56 mmol, 2.5M solution in hexane)(Aldrich), without cooling, to a solution of 3-methoxythiophene (1 g,8.8 mmol) (Aldrich) in dry diethyl ether (5 mL) over a period of 5 min. The mixture was gently heated at reflux for 2 h at which time the organolithium compound was transferred, via cannula, to a solution of DMF (23 mmol) in diethyl ether (5 mL) which was cooled in an ice bath. The reaction was stirred at room temperature for 14 h, at which time 1N HCl (10 mL) was added and the layers were separated. The aqueous layer was extracted with diethyl ether (3×25 mL), and the combined organic extracts were dried over magnesium sulfate, and concentrated to yield 3-methoxy-2-thiophenecarboxaldehyde as a pale, yellow solid. The 3-methoxy-2-thiophenecarboxaldehyde was then added to ethynylmagnesium chloride (Aldrich) according to Method A above to yield 3-hydroxy-3-(3-methoxy-2-thiophenyl)-1-propyne. (Yield 151 mg, 0.9 mmol).