Epichlorohydrin → 2-Hydroxymethyl-1,4-benzodioxan-6-carbaldehyde

Beteiligte Stoffe

Reaktionsschritte

To a cold (5° C.) solution of 3,4-dihydroxybenzaldehyde (3.20 g, 23.2 mmol) in DMF (70 mL) is carefully added NaH (1.96 g 55% in mineral oil, 48.5 mmol) in portions. The temperature rises to 12° C. Upon completion of the addition, the cooling is removed and a solution of 2-chloromethyl-oxirane (2.57 g, 27.7 mmol) in DMF (3 mL) is added. The reaction mixture is stirred at rt overnight. The mixture is diluted with 1N aq. NaOH (150 mL) and extracted with EA (2×200 mL). The organic extracts are washed with 1 M aq. NaOH (2×200 mL) and water (200 mL), combined, dried over MgSO4, filtered and concentrated. The remaining residue is purified by column chromatography on silica gel eluting with heptene/EA 5:1 to 1:1 to afford the title aldehyde (0.53 g) as a solid. LC: tR=0.69 min. 1H NMR (D6-DMSO): δ 9.77 (s, 1H), 7.41 (dd, J=2.3, 8.2 Hz, 1H), 7.36 (d, J=2.3 Hz, 1H), 7.04 (d, J=8.2 Hz, 1H), 5.10 (t, J=5.9 Hz, 1H, D2O exchangeable), 4.37 (dd, J=2.3, 11.1 Hz, 1H), 4.30-4.23 (m, 1H), 4.05 (dd, J=7.6, 11.1 Hz, 1H), 3.67-3.60 (m, 2H).

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