Hydrochloric Acid → 4-Hydroxy-3-(2-propyn-1-yloxy)benzaldehyde

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Reaction Conditions

Reaction Steps

In a dry two-neck flask with a nitrogen inlet, NaH (4.8 g, 200 mmol, 2 equiv) was added into anhydrous DMSO (50 mL) in small portions. While stirring and cooling this solution to 0° C., anhydrous DMSO (60 mL) containing 3,4-dihydroxybenzaldehyde (13.8 g, 100 mmol, 1 equiv) was added dropwise into the flask. This reaction mixture was stirred at rt for 30 min. Propargyl bromide (11.1 mL 100 mmol, 1 equiv) was then added dropwise via syringe and the mixture was stirred at rt overnight. The mixture was poured onto ice, neutralized by a 1 M HCl solution and the product was extracted with ethyl acetate (3×250 mL). The combined organic extracts were concentrated to about 250 mL, washed with brine (5×250 mL) and dried over MgSO4. After filtration the solvent was removed under vacuum to afford crude product as a brownish powder. This was chromatographed on a silica gel column with an eluent of ethyl acetate/hexane/acetic acid (20/80/1) to give 8 as a white powder (12.2 g, yield: 69%). 1H NMR δ=9.84 (s, 1H, —CHO), 7.53 (d, J=1.7, 1H), 7.49 (dd, J1=1.7, J2=8, 1H), 7.09 (d, J=8, 1H), 6.22 (s, 1H, —OH), 4.84 (d, J=2.5, 2H, —OCH2), 2.60 (t, J=2.5, 1H, —C≡CH). 13C NMR δ=190.92 (—CHO), 152.20, 145.37, 129.96, 128.14, 115.35, 111.36, 77.41 (—C≡CH), 77.10 (—C≡CH), 57.23 (—OCH2). HRMS calculated for C10H8O3 (M+), 176.0473; found, 176.0465.

Provenance & Evidence