(2,3-Dihydro-[1,4]dioxino[2,3-B]pyridin-6-YL)methanol → 2H,3H-[1,4]dioxino[2,3-b]pyridine-6-carbaldehyde

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Reaction Steps

To a stirred solution of (2,3-dihydro-[1,4]dioxino[2,3-b]pyridin-6-yl)methanol (24 g, 0.14 mol) in anhydrous CH2Cl2 (500 mL) was added activated MnO2 (25.0 g, 0.28 mol) at 0° C. in portions. The mixture was stirred at room temperature for 5 hours and another batch of activated MnO2 (25.0 g, 0.28 mol) was added in identical fashion. The mixture was stirred at room temperature overnight. The mixture was filtered through a Celite® pad and the filtrate was concentrated. The residue was purified via column chromatography (silica gel, EtOAc/petroleum ether 1:15 to 1:10) to yield 2,3-dihydro-[1,4]dioxino[2,3-b]pyridine-6-carbaldehyde (16.0 g, 67%) as a yellow solid. MS (ES+) 166.2 (M+H)+. 1H NMR δ (CDCl3) 4.40 (s, 2H), 4.91 (s, 2H), 7.37 (d, 1H), 7.61 (d, 1H), 9.65 (s, 1H).

Provenance & Evidence